BIOMECHANICS

1

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

DEFINITION

Biomechanics uses the laws of physics and engineering mechanics as well as biological and physiological principles to describe the motions of various body segments (kinematics) and understand the effects of forces and moment (kinetics) acting on the body

Occupational Biomechanics is a sub-discipline within the general field of biomechanics that studies the physical interaction of workers with their tools machines and materials to enhance worker performance while minimizing the risk of musculoskeletal injury

WHYbull Prevent problems that can cause injury to workers ie

Musculoskeletal Disorders (MSDs)

bull Improvement of (manual) working conditions

bull Improving organizational performance (efficiency

quality worker satisfaction)

bull EASNEP

COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE

1 less production output

2 increased lost time

3 higher medical costs

4 increased absenteeism

5 higher material costs

6 low-quality work

7 injuries sprains strains

8 increased probability of accidents and errors

9 increased labor turnover

10 less spare capacity to deal with emergencies

Source Total Cost ($) Notes

In-plant medicalvisits and treatments

14050 $50 per visit

Employee absences 127905 Each 1-week absencerequired 1 replacement worker

Work restrictions 16192 12 of the work restrictions required replacement workers

Job changes initiated by employee

13984 Each job change required retraining for 2 workers

Total Biaya 172131

Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)

CASE SHOULDER DISORDERS

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DEFINITION

Biomechanics uses the laws of physics and engineering mechanics as well as biological and physiological principles to describe the motions of various body segments (kinematics) and understand the effects of forces and moment (kinetics) acting on the body

Occupational Biomechanics is a sub-discipline within the general field of biomechanics that studies the physical interaction of workers with their tools machines and materials to enhance worker performance while minimizing the risk of musculoskeletal injury

WHYbull Prevent problems that can cause injury to workers ie

Musculoskeletal Disorders (MSDs)

bull Improvement of (manual) working conditions

bull Improving organizational performance (efficiency

quality worker satisfaction)

bull EASNEP

COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE

1 less production output

2 increased lost time

3 higher medical costs

4 increased absenteeism

5 higher material costs

6 low-quality work

7 injuries sprains strains

8 increased probability of accidents and errors

9 increased labor turnover

10 less spare capacity to deal with emergencies

Source Total Cost ($) Notes

In-plant medicalvisits and treatments

14050 $50 per visit

Employee absences 127905 Each 1-week absencerequired 1 replacement worker

Work restrictions 16192 12 of the work restrictions required replacement workers

Job changes initiated by employee

13984 Each job change required retraining for 2 workers

Total Biaya 172131

Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)

CASE SHOULDER DISORDERS

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

WHYbull Prevent problems that can cause injury to workers ie

Musculoskeletal Disorders (MSDs)

bull Improvement of (manual) working conditions

bull Improving organizational performance (efficiency

quality worker satisfaction)

bull EASNEP

COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE

1 less production output

2 increased lost time

3 higher medical costs

4 increased absenteeism

5 higher material costs

6 low-quality work

7 injuries sprains strains

8 increased probability of accidents and errors

9 increased labor turnover

10 less spare capacity to deal with emergencies

Source Total Cost ($) Notes

In-plant medicalvisits and treatments

14050 $50 per visit

Employee absences 127905 Each 1-week absencerequired 1 replacement worker

Work restrictions 16192 12 of the work restrictions required replacement workers

Job changes initiated by employee

13984 Each job change required retraining for 2 workers

Total Biaya 172131

Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)

CASE SHOULDER DISORDERS

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE

1 less production output

2 increased lost time

3 higher medical costs

4 increased absenteeism

5 higher material costs

6 low-quality work

7 injuries sprains strains

8 increased probability of accidents and errors

9 increased labor turnover

10 less spare capacity to deal with emergencies

Source Total Cost ($) Notes

In-plant medicalvisits and treatments

14050 $50 per visit

Employee absences 127905 Each 1-week absencerequired 1 replacement worker

Work restrictions 16192 12 of the work restrictions required replacement workers

Job changes initiated by employee

13984 Each job change required retraining for 2 workers

Total Biaya 172131

Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)

CASE SHOULDER DISORDERS

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

Source Total Cost ($) Notes

In-plant medicalvisits and treatments

14050 $50 per visit

Employee absences 127905 Each 1-week absencerequired 1 replacement worker

Work restrictions 16192 12 of the work restrictions required replacement workers

Job changes initiated by employee

13984 Each job change required retraining for 2 workers

Total Biaya 172131

Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)

CASE SHOULDER DISORDERS

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

HUMAN SYSTEMS

bull In order to create EASNEP we need to know human limitation capability and function

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

HUMAN SYSTEM

sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MUSCULOSKELETAL

1 Tulang (Bones)

2 Jaringan penghubung (Connective Tissue)

3 Sendi (Joints)

4 Otot (Muscle)

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

1 BONES YOU NEED TO KNOW

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)

Ligaments

ndash connect bones to bones

ndash eg lateral collateral in knee

Tendons

ndash connect muscles to bones

- eg rotator cuff multiple tendons within

carpal tunnel

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CONNECTIVE TISSUE AND BONES FUNCTIONS

1 Force transmission and movement

2 Posture support

3 Metabolism (blood cell manufacture)

4 Protection

5 StorageBuffer (calcium and phosphorus)

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

JOINTSbull Interface between two bones

bull Provides motion and pulleys for tendons

bull Synovial Joint

bull most common typebull no tissue synovial fluid forms

interfacebull Examples wrist elbow knee

shoulder

bull Cartilaginous

bull some motion but high load bearingbull Example spine

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MUSCLE Muscle Functions

ndash skeletal motion

ndash skeletal stability

ndash force production

Muscle mass (untrained) = 30-50 of total body mass

Muscle Composition

ndash 75 water

ndash 20 proteins

ndash 5 other (carbohydrates fats enzymes salts hellip)

Type Control

Smooth Autonomic (involuntary) NS

Skeletal Somatic (voluntary) NS

Cardiac Autonomic NS

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MUSCLE CONTRACTION

1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin

1048708 Membrane depolarization causes release of Ca2+

1048708 Ca2+ reacts with protein on actin molecule to expose binding sites

1048708 Myosin binds to actin and ratchets up (sliding)

1048708 Each event yields ~50-100Aring displacement

1048708 Energy required for unbinding

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

BIOMECHANICS ANALYSIS (1)

Analisis

sum Moment = 0

(LR) -(Fr)-(Wr2) = 0

F = (LR)- (Wr2) r

sum Gaya = 0

J+W = F + LJ

Wr2 J= F + L - W

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

BIOMECHANICS ANALYSIS (2)

Analisis

sum Moment = 0

Fr = (L(R+r))+(Wr2)

F = (L(R+r))+(Wr2)) r

sum Gaya = 0

J = F ndash L - W

J

W

r2

(Fr)-(L(R+r))+(Wr2)=0

Wr2

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

SIGN CONVENTIONS FOR CALCULATIONS

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

LATIHAN

Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum)

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

JAWAB

a) Gaya kerja Otot Triceps

sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N

b)Beban pada tumpuan sendi siku

sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

LATIHAN

J

W = 25N13cm

5cm 28cm

= 400 N

Hitung a) Kekuatan otot yang diperlukan utk

mengangkat bebanb) Gaya yang diterima oleh sendi siku

(fulcrum) c) Berapa massa beban jika diketahui

keuntungan mekanis menggunakan katrol adalah 1

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions

Compensation costs (2000)

Reaching pump from top of the cart $800

Lifting pump from line $57000

Repetitive lifting of pump $55000

Repetitive assembly work $10000

Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

BIOMECHANICS

MANUAL MATERIALS HANDLING

25

Yusuf Nugroho Doyo Yekti (YFN)

doyoyektiyahoocom

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

LESSON OVERVIEWWhat is MMH

MMH Activities

MMH Effect on Health

Recommended Weight Limit (RWL)

Case 1 Effect of Frequency Factor on RWL

Case 2 Effect of Horizontal Distance on RWL

Case 3 Effect of Vertical Distance on RWL

26

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

WHAT IS MANUAL MATERIALS HANDLING

Manual Materials Handling (MMH)

bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks

bull Either one-time (infrequent) dutybull or as part of regular work

MMH involves five types of activities

1 LiftingLowering

2 PushingPulling

3 Twisting

4 Carrying

5 Holding

27

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH ACTIVITIESLiftingLowering

bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your

handsbull Lowering is the opposite activity of lifting

PushingPulling

bull Pushing to press against an object with force in order to move the object

bull The opposite is to pull

Twisting

bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position

bull Twisting can take place while the entire body is in a state of motion

28

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH ACTIVITIES (CONT)

Carrying

bull Having an object in onersquos grasp or attached while in the act of moving

bull Weight of object becomes a part of the total weight of the person doing the work

Holding

bull Having an object in onersquos grasp while in a static body position

29

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain

About frac34 workers whose job includes MMH suffer pain due to back injury at some time

Such back injuries account for 13 of all lost work + 40 of all congcompensation costs

More important than financial cost human suffering

rArrprevention of back injuriescrucial challenging problem for occupational health and safety

30

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Most common causes of back injuries

bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout

Weight of the load lifted

bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries

Range of the lift

bull Preferred range for lifting isbetween knee and waist height

bull Lifting abovebelow this range is more hazardous

Location of load in relation to the body

bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body

31

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Size and shape of load

bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body

bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position

Number and frequency of lifts performed

bull How often the worker performs MMH tasks and for how long are extremely important factors

bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury

bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr

32

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH

Excessive bending and twisting

bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr

bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr

and bendingbull eg unsuitable dimensions of benches tables and other furniture

force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr

bull eg work areas overcrowded with people or equipment stressful rArrbody movements

33

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)

following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo

NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury

34

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body

bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit

bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)

A load constant (LC)

bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for

bull 75 of femalesbull 90 of males

The recommended weight limit (RWL)

bull Calculated using the NIOSH lifting equation

35

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task

Six variables considered in determining RWL

1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles

2 starting height of the hands from the ground (vertical location V)

3 vertical distance of lifting (D)

4 frequency of lifting or time between lifts (F)

5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)

6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)

36

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts

STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)

RWL = LC x HM x VM x DM x FM x AM x CM

bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor

37

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CALCULATING THE RWL (CONT)

38

(AM)

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CALCULATING THE RWL (CONT)STEP 3 analyze RWL

If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)

If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly

39

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)

bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object

bull Write down this numberbull Look up the number on the horizontal distance chart and find the

matching multiplier factorrdquobull Use this factor in the lifting equation

Repeat this process for the other 5 factors

40

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)

bull Thisrsquos vertical distance of the hands from the ground at the start of the lift

bull Measure this distance (cm)bull Determine corresponding VM value on the chart

Distance Multiplier

bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart

41

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)

bull Thisrsquos how often lift is repeated in a time periodbull Determine

bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)

bull how much time there is for rest between lifts

Asymmetric Multiplier (AM)

bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)

42

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)

bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as

bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor

bull You also need to know if the lift is done in a standing or stooping position

43

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL

Compare RWL to actual weight of the object

If the RWL lt lower than actual object weight

bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest

multiplier valuesbull modify the lift accordingly

44

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering

bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion

(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling

(high risk of a slip or fall)

45

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with

bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings

Calculation of RWL using the formula

bull Indicates which of the six components of the task contribute most to the risk

bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo

bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that

not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations

than the first equation

46

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESHorizontal Multiplier (HM)

bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object

bull Determine HM from chart below

47

H = Horizontal Distance (cm)

HM Factor

25 or less 100

30 083

40 063

50 050

60 042

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESVertical Multiplier (VM)

bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift

bull Determine VM

from chart below

48

V = Starting Height (cm)

VM Factor

0 078

30 087

50 093

70 099

100 093

150 078

175 070

gt175 000

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESDistance Multiplier (DM)

bull Find the vertical distance (D in cm) that the load travelsbull Determine DM

from chart below

49

D = LiftingDistance (cm)

DM Factor

25 or less 100

40 097

55 090

100 087

145 085

175 085

gt175 000

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESAsymmetric Multiplier (AM)

bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below

50

A = Angle (ordm)

AM Factor

90deg 071

60deg 081

45deg 086

30deg 090

0deg 100

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESFrequency Multiplier (FM)

bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift

bull Determine FM from chart below

51

F=Time Between Lifts

FM Factor

Lifting While Standing

Lifting While Stooping

One Hour or Less

Over One Hour One Hour or Less

Over One Hour

5 min 100 085 100 085

1 min 094 075 094 075

30 sec 091 065 091 065

15 sec 084 045 084 045

10 sec 075 027 075 027

6 sec 045 013 045 -

5 sec 037 - 037 -

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

MULTIPLIER VALUESCoupling Multiplier (CM)

bull Find the quality of grasp (or coupling C) classified as good fair or poor

bull This depends on the body position (either standing or stooping)bull Determine CM from chart below

52

C = GraspCM Factor

Standing Stooping

Good (handles) 100 100

Fair 100 095

Poor 090 090

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation

RWL = 23 Kg HM VM DM AM FM CM

Summary of steps

bull find out the values for the different multipliers for the MMH in question

bull solve for the RWLbull If RWL ge weight of the object handled rArr

bull task is safe

bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned

53

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours

54

6 sec

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task

1 Determine the weight of the loadWeight = 10 kg

2 Assess the six components of lifting task

55

H (Horizontal Distance) 20 cm

V (Vertical Distance) 75 cm

D (Lifting carrying Distance) 0 cm

A (Angle) 90deg

F (Frequency) 6 sec

C (Couplingquality of grip) fair

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting

component from the appropriate tables

56

H (Horizontal Distance) 20 cm HM 1

V (Vertical Distance) 75 cm VM 1

D (Lifting carrying Distance)

0 cm DM 1

A (Angle) 90deg AM 071

F (Frequency) 6 sec FM 013

C (Couplingquality of grip) fair CM 1

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task

RWL = 23 kg 1 99 1 071 013 1

= 2 1 kg

5 Compare weight of the load against determined weight limit for the task

weight of load (10 kg) gt RWL (21 kg)

6 Conclusion Task is Dangerous

57

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations

Assess which component(s) contribute(s) most to the risk

bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task

Shorten the frequency of lifting by

a reducing the frequency of incoming boxes(ie increasing F) andor

b assigning additional workers to task andor

c shortening the time of the task to 1 hour

58

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)

59

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task

Assess the six components in the redesigned task

Determine new RWL

RWL = 23 kg 1 99 1 071 075 1

= 121 kg

Compare weight of the box against determined weight limit for redesigned task

weight of load (10 kg) now lt RWL (121 kg)

Conclusionmost workers can perform the task safely (why most)

60

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement

Analyze the following work task

A worker lifts 15 kg boxes from the table to the shelf five times an hour

Notice that there is a barrier between the worker and the box

61

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL

CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement

Analyze the following work task

A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour

62

• Biomechanics
• definition
• WHY
• Costs of Ignoring Ergonomics in the Workplace
• Case Shoulder Disorders
• Slide 6
• Human Systems
• Human SYSTEm
• Musculoskeletal
• 1 BONES you need to know
• extremities
• 2 Jaringan penghubung (Connective Tissue)
• Connective Tissue and Bones Functions
• Joints
• Muscle
• Slide 16
• Muscle Contraction
• BIOmechanics analysis (1)
• BIOmechanics analysis (2)
• Sign Conventions for Calculations
• latihan
• jawab
• LAtihan
• A Success Storyhellip
• Biomechanics (2)
• Lesson Overview
• What is Manual Materials Handling
• MMH Activities
• MMH Activities (cont)
• MMH Effect on Health
• MMH Effect on Health (cont)
• MMH Effect on Health (cont) (2)
• MMH Effect on Health (cont) (3)
• Establishing if a Lift is too Heavy
• Establishing if a Lift is too Heavy (cont)
• Calculating the RWL
• Calculating the RWL (cont)
• Calculating the RWL (cont) (2)
• Calculating the RWL (cont) (3)
• Determining the Multiplier Value
• Determining the Multiplier Value (cont)
• Determining the Multiplier Value (cont) (2)
• Determining the Multiplier Value (cont) (3)
• Determining the Multiplier Value (cont) (4)
• Applicability of NIOSH Lifting Equation
• Applicability of NIOSH Lifting Equation (2)
• Multiplier Values
• Multiplier Values (2)
• Multiplier Values (3)
• Multiplier Values (4)
• Multiplier Values (5)
• Multiplier Values (6)
• Revised NIOSH Lifting Equation
• Case 1 Effect of Frequency Factor on RWL
• Case 1 Effect of Frequency Factor on RWL (2)
• Case 1 Effect of Frequency Factor on RWL (3)
• Case 1 Effect of Frequency Factor on RWL (4)
• Case 1 Effect of Frequency Factor on RWL (5)
• Case 1 Effect of Frequency Factor on RWL (6)
• Case 1 Effect of Frequency Factor on RWL (7)
• Case 2 Effect of Horizontal Dist on RWL
• Case 3 Effect of Vertical Distance on RWL