mechanical drives & power transmission

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Basic Mechanical Drives and Power Transmission Training

December 2007

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Mechanical Drives/Power Transmission Training

The purpose of this presentation is to

provide a overview of industrial drives and their maintenance.

Gear Drives Belt Drives V-Belt Maintenance Chain Drives Sprocket and Roller Chain Maintenance

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Gear Drives

December 2007

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Mechanical Drives/Power Transmission Training

Gear Boxes

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Mechanical Drives/Power Transmission Training

Types

Types Automotive transmissions Auxiliary transmissions Transfer cases Power takeoffs Marine gears Hydraulic drives Industrial transmissions Differentials

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Mechanical Drives/Power Transmission Training

Gear Boxes

Series trains Planetary gearing Speed reducers

Base mountedShaft mounted

Speed increasers

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Mechanical Drives/Power Transmission Training

Gears and Gear Boxes

A gear is a form of disc, or wheel, that has teeth around its periphery for the purpose of providing a positive drive by meshing the teeth with similar teeth on another gear or rack.

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Mechanical Drives/Power Transmission Training

Right Angle Gear Drive

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Mechanical Drives/Power Transmission Training

Spur Gears

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Mechanical Drives/Power Transmission Training

Involute Curve

Cord

Base Circle

Circle involute

Circle

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Mechanical Drives/Power Transmission Training

Pressure Angle

Pressure Angle

Pressure angle

Pressure angle

RotationLine of action

14 ½ ° 20°

Direction of tooth to

tooth push

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Mechanical Drives/Power Transmission Training

Pitch Diameter and Center Distance

2

21 DDC

+= 221 DCD −=Center Distance C

Pitch Diameter D1

Pitch Diameter D2

122 DCD −=

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Mechanical Drives/Power Transmission Training

Circular/Diametrical Pitch

Circular Pitch

3.1416”

1 2 3 4 5 6 7 8 9 10

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Mechanical Drives/Power Transmission Training

Names of Gear Parts

Clearance

Pitch Circle

Addendum

Pitch Circle

DedendumWhole depth

Working depth

ThicknessCircular

pitchPitch Line

Addendum

Dedendum Whole depth

Thickness

Circular pitch

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Mechanical Drives/Power Transmission Training

Backlash

Backlash

Pitch Line

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Mechanical Drives/Power Transmission Training

Other Gear Types

Bevel and Miter Helical Worm Herringbone

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Mechanical Drives/Power Transmission Training

Bevel and Miter Gear

Shaft Angle

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Mechanical Drives/Power Transmission Training

Helical

Helix angle

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Mechanical Drives/Power Transmission Training

Worm Gear

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Mechanical Drives/Power Transmission Training

Herringbone Gear

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Mechanical Drives/Power Transmission Training

Gear Damage

Vibration Frequency Component – gear mesh Normal profile

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Mechanical Drives/Power Transmission Training

Troubleshooting

Inappropriate bidirectional operation Gear overload Misalignment Poor maintenance Induced misalignment Visual inspection

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Mechanical Drives/Power Transmission Training

Wear patterns

Normal

Abrasives in lubricating oil

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Mechanical Drives/Power Transmission Training

Pattern caused by corrosive attack on gear teeth

Pitting caused by gear overloading

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December 2007 Belt Drives

Belt Drives

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Mechanical Drives/Power Transmission Training

Introduction

DescriptionBasic Components

Load carrying sectionRubber compression sectionCover

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Mechanical Drives/Power Transmission Training

Belt Drives

Belt drives are used to transmit power between a drive unit and a driven unit

Drive Motor

Driven Unit

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Mechanical Drives/Power Transmission Training

Belts

The size of the belt must match the sheave size. if they do not match, then the belt will not make proper contact with the sheave and will decrease the amount of load it can transmit.

A

AB

B

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Mechanical Drives/Power Transmission Training

Belt Selection

Standard V-Belt Cogged Belt

Joined V-Belt Positive Drive Belt

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Mechanical Drives/Power Transmission Training

Sheaves

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Mechanical Drives/Power Transmission Training

Shaft Speed

erave_diametDriven_she

_rpmdriveshaftncheseDiameterIDriveSheavt_rpmDrivenShaf

×=

12 inch dia.

6 in dia.

1800 rpm

DriveDriven

rpm

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Mechanical Drives/Power Transmission Training

Driven Sheave Diameter

ft_rpmDriven_sha

_rpmdriveshaftncheseDiameterIDriveSheavveDiameterDrivenShea

×=

___ inch dia.

6 in dia.

1800 rpm

DriveDriven

900 rpm

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Mechanical Drives/Power Transmission Training

Belt Length

12 inch dia.

6 in dia.

DriveDriven

35 inches

2centercenter_to_2

3.14meterdriven_dia2

3.14eterdrive_diamhBelt_lengt ×+×+×=

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Mechanical Drives/Power Transmission Training

Belt Speed

12

14.3 rpmdiameterFPM

××=

12 inch dia.

6 in dia.

1800 rpm

DriveDriven

900 rpm

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December 2007

V-Belt Maintenance

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Mechanical Drives/Power Transmission Training

Belt Maintenance

Routine maintenance is essential if a belt drive is to operate properly

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Mechanical Drives/Power Transmission Training

Belt Maintenance

Never force belt onto sheave Belt should not ride on bottom of sheave. Check belt condition Belt alignment Tension Inspect sheaves and shafts Belt stretch

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Mechanical Drives/Power Transmission Training

How to Read V-belt Numbers

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Mechanical Drives/Power Transmission Training

Classic Cog V-belts AX-BX-CX-DX

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Mechanical Drives/Power Transmission Training

D-V Wedge Belts 3VX-5VX-8V

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Mechanical Drives/Power Transmission Training

Classic V-belts A-B-C-D-E

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Mechanical Drives/Power Transmission Training

V-belt Inspection

Slapping Squealing Check belt

condition Tightness Tension

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Mechanical Drives/Power Transmission Training

V-belt Sidewall Wear

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Mechanical Drives/Power Transmission Training

V-belt Worn Cover/soft or Swollen

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Mechanical Drives/Power Transmission Training

V-belt Slips, Squeals (Spin Burn)

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Mechanical Drives/Power Transmission Training

V-belt Underside Cracked

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Mechanical Drives/Power Transmission Training

V-Belt Cover Split / Missing Cogs

Belts pried upon Foreign objects Excessive heat Sheave too small Sheave misaligned Improper storage

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Mechanical Drives/Power Transmission Training

Sheave Inspection

Sheave groves must be

like this

not this

Dished out

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Mechanical Drives/Power Transmission Training

Sheave Inspection

5V

10.01-16.0O.D.

40 deg

Under 10.0O.D.

38 deg

Over 16.0O.D.

42 deg

Example sheave gauge

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Mechanical Drives/Power Transmission Training

Alignment

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Mechanical Drives/Power Transmission Training

Types of Misalignment

Angular Misalignment

Parallel Misalignment

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Mechanical Drives/Power Transmission Training

Shaft Alignment

Cord tied to shaft

Cord touching sheaves at points indicated by arrows

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Mechanical Drives/Power Transmission Training

Tensioning V-belts Drives

Too tight

Too loose

Slight bow

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Mechanical Drives/Power Transmission Training

Check Tension

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Mechanical Drives/Power Transmission Training

Preventative Maintenance

Check belt condition Check belt tension Identify sources of contamination Check sheave alignment Check sheave wear

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December 2007

Chain Drives

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Mechanical Drives/Power Transmission Training

Introduction

DescriptionTypes of links

Self forming teethExtended Pin

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Mechanical Drives/Power Transmission Training

Introduction

DRIVEN ROLL

DRIVE GEAR BOX

Chain Pitch

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Mechanical Drives/Power Transmission Training

Chain Drive

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Mechanical Drives/Power Transmission Training

Advantages No slippage More compact than belt Good for slow speeds Easier to install Not subject to deterioration Operates under wet conditions Less adjustment required Can drive several shafts Less costly than gear drives

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Mechanical Drives/Power Transmission Training

Disadvantages Cannot be used where drive must slip Cannot except misalignment Noisy Causes vibration Needs frequent lubrication Small load capacity Shorter Service Live

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Mechanical Drives/Power Transmission Training

Chain Drive Principles

Drive chain

Drive Sprocket

Sprocket

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Mechanical Drives/Power Transmission Training

Shaft Speed

teethcket_#DrivenSpro

_rpmdriveshaftteethket_#DriveSproct_rpmDrivenShaf

×=

12 T 6 T

1800 rpm

DriveDriven

rpm

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Mechanical Drives/Power Transmission Training

Chain Length Calculation

( )2nterCenterToCe2

PitchcketTeethDrivenSpro2

PitchketTeethDriveSprochChainLengt

×+×+×=

12 T 6 T

DriveDriven

35 inches

40 Chain

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Mechanical Drives/Power Transmission Training

Chain Speed

12

rpmpitchteethFPM

××=

12 T 6 T

1800 rpm

DriveDriven

900 rpm

40 Chain

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Mechanical Drives/Power Transmission Training

Some Chain Drive Examples

Fork Lift Roller Conveyor

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December 2007

Sprocket and Roller Chain Maintenance

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Mechanical Drives/Power Transmission Training

Roller Chain

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Mechanical Drives/Power Transmission Training

Pitch

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Mechanical Drives/Power Transmission Training

Large Pitch Conveyor Chain

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Mechanical Drives/Power Transmission Training

Chain Part Friction Areas

Major friction areas in red

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Mechanical Drives/Power Transmission Training

Lubrication Methods

Hand Oiling Drop Lubrication Oil Bath Rotating Plate Forced Circulation

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Mechanical Drives/Power Transmission Training

Example Application Large Roller Chain Multi-strand conveyor

Large Roller Chain

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Mechanical Drives/Power Transmission Training

Sprockets

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Mechanical Drives/Power Transmission Training

Sprocket Classifications

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Mechanical Drives/Power Transmission Training

Chain Drive Factors

Location of slack Chain wrap Vertical arrangement

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Mechanical Drives/Power Transmission Training

Installation – Parallel Shafts

Level

Level

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Mechanical Drives/Power Transmission Training

Installation

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Mechanical Drives/Power Transmission Training

Installation - Sprockets

Straight edge or Straight string

Gap

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Mechanical Drives/Power Transmission Training

Installation

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Mechanical Drives/Power Transmission Training

Chain LengthThe following information is needed for an equation to find the chain length:

1. Number of teeth on the drive sprocket. 2. Number of teeth on the driven sprocket. 3. Center-to-center distance between the shafts. 4. The chain pitch in inches.

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Mechanical Drives/Power Transmission Training

Chain Inspection Cleanliness Lubrication Signs of wear Flexibility Check chain stretch Physical damage

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Mechanical Drives/Power Transmission Training

Chain Wear

WORN CHAIN

NEW CHAIN

SPROCKET

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Mechanical Drives/Power Transmission Training

Sprocket Tooth Wear SPROCKETS INDICATE

WEAR HERE

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Mechanical Drives/Power Transmission Training

Preventive Maintenance

Inspect for wear Lubricate Check chain sag Set tension Inspect sprockets

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Mechanical Drives/Power Transmission Training

Summary and Quiz

Review Objectives Question and Answer Session