automobile laboratory manual (be)

Yadav Rahul N.(Solapur-MH)

A Laboratory Manual for

Automobile Engineering

Degree in

Mechanical Engineering (BE-II)


Guidelines for teachers:

Teachers shall discuss the following points with students before start of practicals of the subject.

1. Learning Overview: To Develop better understanding of importance of the subject. To know related skills to be developed such as intellectual skills and Motor Skills.

2. Link / Block Diagram: Context of the subject in the form of link diagram showing interrelationship of various subject areas, curriculum objectives and job profile.

3. Graphical structure: In this, topics and sub topics are organized in systematic way so that ultimate purpose of learning the subject is achieved. This is arranged in the form of fact, concept, principle, procedure, application and problem.

4. Know your Laboratory work: To understand the layout of laboratory, specifications of Equipment /Instruments/ Materials, procedure, working in groups, planning time etc. Also to know total amount of work to be done in the laboratory.

5. Teacher shall ensure that required equipment are in working condition before start of experiment, also keep operating instruction manual available.

6. Explain prior concepts to the students before starting of each experiment. 7. Involve students activity at the time of conduct of each experiment. 8. While taking reading/observation each student (from batch of 20 students) shall be given a

chance to perform/observe the experiment. 9. List of questions is given at the end of each experiment. Teacher shall instruct the students

to attempt all questions given at the end of each experiment / exercise. Teacher shall ensure that each student writes the answers to the allotted questions in the laboratory manual after performance is over.

10. If the experimental setup has variations in the specifications of the equipment, the teachers are advised to make the necessary changes, wherever needed

11. Teacher shall assess the performance of students continuously as per norms prescribed by University.

12. Teacher should ensure that the respective skills and competencies are developed in the students after the completion of the practical exercise.

13. Teacher is expected to share the skills and competencies to be developed in the students. 14. Teacher may provide additional knowledge and skills to the students even though not

covered inthe manual but are expected from the students by the industries. 15. Teachers shall ensure that industrial visits recommended in the manual are covered. 16. Teacher may suggest the students to refer additional related literature of the technical

papers /reference books / Seminar Proceedings, etc. 17. During assessment teacher is expected to ask questions to the students to tap their

achievements regarding related knowledge and skills so that students can prepare while submitting record of the practical. Focus should be given on development of enlisted skills rather than theoretical/codified knowledge.

18. Teacher should enlist the skills to be developed in the students that are expected by the industry. Teacher should organise Group discussions / brain storming sessions/ Seminars to facilitate the exchange of knowledge amongst the students.


Instructions for students: 1. Students shall read the points given below for understanding the theoretical concepts &

practical applications. 2. Listen carefully to the lecture given by teacher about importance of subject, curriculum

philosophy, graphical structure, and skills to be developed, information about equipment, instruments, procedure, method of continuous assessment, tentative plan of work in laboratory and total amount of work to be done in a year.

3. Students shall undergo study visit of the laboratory for types of equipment, instruments, material to be used, before performing experiments.

4. Read the write up of each experiment to be performed, a day in advance. 5. Organize the work in the group and make a record of all observations. 6. Understand the purpose of experiment and its practical implications. 7. Student should not hesitate to ask any difficulty faced during conduct of practical /

exercise. 8. The student shall study all the questions given in the laboratory manual and practice to

write the answers to these questions 9. Student shall visit the recommended industries and should study the knowhow of the shop

floor practices and the operations of machines. 10. Student shall develop maintenance skills as expected by the industries. 11. Student should develop the habit of pocket discussion / group discussion related to the

experiments/ exercises so that exchanges of knowledge / skills could take place. 12. Student shall attempt to develop related hands-on-skills and gain confidence. 13. Student shall focus on development of skills rather than theoretical or codified

knowledge. 14. Student shall visit the nearby workshops, workstation, industries, laboratories, technical

exhibitions, trade fair etc. even not included in the Lab Manual. In short, students should have exposure to the area of work right in the student hood.

15. Student shall insist for the completion of recommended Laboratory Work, industrial visits, answers to the given questions, etc.

16. Student shall develop the habit of evolving more ideas, innovations, skills etc. than included in the scope of the manual.

17. Student shall refer technical magazines, proceedings of the Seminars, refer websites related to the scope of the subjects and update their knowledge and skills.

18. Student should develop the habit of not to depend totally on teachers but to develop self learning techniques.

19. Student should develop the habit to react with the teacher without hesitation with respect to the academics involved.

20. Student should develop habit to submit the practicals exercise continuously and progressively on the scheduled dates and should get the assessment done.

21. Student should be well prepared while submitting the write up of the exercise. This will develop the continuity of the studies and he will not be over loaded at the end of the term.


List of Experiments & Record of Progressive Assessment.

Sr. No.

Name of the Experiments Date of

Performs

Assessment Max.

Marks (10)

Sign& Remarks of

Teacher

1 Study and demonstration of four wheeler chassis layout. Two-wheel & fourwheel driv layouts.

2 Study and Demonstration of working of automobile clutch.

3 Study and demonstration of Automobile gearbox.

4 Study and demonstration of final drive and differential.

5 Study and demonstration of working Hydraulic braking system.

6 Study and demonstration of front wheel steering geometry and steering mechanism.

7 Study and demonstration of suspension system of a four-wheeler.

8 Study and demonstration of battery, electrical charging system.

9 Study and demonstration of electrical starting system.

10

Study and demonstration of a] D. C. Electric horn. (a) Electric Fuel Gauge (b) Electric fuel Gauge. (c) Flasher unit. (d) Wiper circuit


Experiment No. 01

Study and demonstration of four wheeler chassis layout. Two-wheel and four wheels drive layouts.


EXPERIMENT NO 1.

Title Study and demonstration of four wheeler chassis layout. Two-wheel and four wheels

drive layouts.

AIM To study four Wheeler chassis layout and two wheel and four wheel drive arrangement.

Objetives -

To study four wheeler.

To study types of chassis.

To study two wheel drive arrangement.

To study four wheel drive arrangement.

Different between two and four wheel drive arrangement.

Introduction:-

Chassis

The chassis is a part of automobile which supports its body, engine and

transmission system. It is a complete operating unit, which is a capable of running with its

own power. Chassis is defined as without body structure.

Automotive chassis is considered to be one of the significant structures of an

automobile. It is usually made of a steel frame, which holds the body and engine of an

automotive vehicle. More precisely, automotive chassis or automobile chassis is a skeletal

frame on which various mechanical parts like engine, tires, axle assemblies, brakes, steering

etc are bolted. At the time of manufacturing, the body of a vehicle is flexibly molded

according to the structure of chassis. Automobile chassis is usually made of light sheet metal

or composite plastics. It provides strength needed for supporting vehicular components and

payload placed upon it. Automotive chassis or automobile chassis helps keep an automobile

rigid, stiff and unbending. Auto chassis ensures low levels of noise, vibrations and harshness

throughout the automobile


Component of chassis

Chassis includes following components.

1. Frame.

2. Engine with radiator.

3. Transmission system.

4. Wheel and Tires.

5. Suspension system.

6. Braking system.

7. Steering mechanism.

8. Electrical system.

9. Fuel and air tank.

Types of chassis:-

A)Full forwarded chassis. -

In this type of chassis, engine is mounted completely outside the driver cabin.

B) Semi forwarded chassis

In this type of chassis engine is so mounted that half of its in the drivers cabin where as

the other half is in front outside the driver.

C) Bus Chassis: - In bus chassis the engine is mounted completely inside the driver cabin,

so that driver should see the road just in front of front wheel.

D) Overhang Chassis: - Overhang chassis are chassis in which the chassisis overhang after

rear wheel this type chassis is used in bus, in this more space are provide.

E) Long Wheel Base Chassis:-

Standard truck chassis are used for making trucks and to permit the truck to carry, the

exact weight but in case of bus chassis seats are fixed and the distance between each seat is

fixed. The vehicle will be running with less weight as less no. of passenger and to carry

more weight bus chassis are provide with longer wheel base.


Experiment NO - 2.

Study, Demonstration and Working of Automobile Clutch.


EXPERIMENT NO - 2.

Title - Study and Demonstration of working of Automobile clutch.

AIM - To study Automobile clutch assembly.

Objectives -

To study function & requirement of clutch.

To study classification of clutch.

To study construction & working of single plate automobile clutch.

To study components of single plate automobile clutch.

To demonstrate on single plate automobile clutch.

Introduction-

Clutch is used to engage or disengage the engine to the transmission or gear box.

When the clutch is in engaged position, the engine power or rotary motion of engine

crankshaft is transmitted to gear box and then to wheels. When clutch is disengaged, the

engine power does not reach to gear box (and to wheels) although engine is running.

Clutch is also used to allow shifting or changing of gears when vehicle is running. For

shifting gears, clutch is first disengaged then gear is shifted and then clutch is engaged.

Clutch has to be disengaged to stop the vehicle and also at the time of idling.

Functions -

1. To engage or disengage engine and rotation part.

2. To transmit power to transmission system without shocks & jerks.

3. To permit engagement to gears without damage when vehicle is in motion.

Principle of clutch

It operates on the principle of friction. When two surfaces are brought in

contact and are held against each other due to friction between them, they can be used

to transmit power. If one is rotated, then other also rotates. One surface is connected

to engine and


other to the transmission system of automobile. Thus, clutch is nothing but a

combination of two friction surfaces.

Requirements -

a) Torque Transmission.

The clutch should be able to transmit the max torque of engine.

b) Gradual Engagement.

The clutch should take drive (positively) gradually without the occurrence of sudden

jerks.

c) Heat dissipation

At the time of clutch operation large amount of heat is generated the proper adequate

dissipation of heat.

d) Vibration damping

Suitable mechanism should be incorporated within the clutch, so that noise produced

in transmission is eliminated.

e) Dynamic balancing

This is necessary particular high speed clutches.

f) Size - The size of clutch is must smallest so that it can occupy minimum amount of

space.

g) Clutch free pedal play-

To reduce effective clamping load on carbon thrust bearing & wear therefore

sufficient clutch pedal play must be provided in clutch.

h) Ease of operation

For higher power transmission the operation of disengaging clutch must not be

tiresome to the driver.


Types of clutch

Some types of clutches used in vehicles are given below :

A. Friction Clutch : It may be

(I) Single plate clutch, (II) Multi-plate clutch, or (III) Cone clutch.

Multi-plate clutch can be either wet or dry. A wet clutch is operated in an oil batch

whereas a dry clutch does not use oil.

B.Centrifugal clutch.

a. Semi-centrifugal clutch.

b. Hydraulic clutch.

c. Positive clutch.

d. Vacuum clutch.

e. Electromagnetic clutch.

Main components of clutch-

1. Flywheel.

2. Clutch plate.

3. Pressure plate.

4. Cover.

5. Releasing leaver with draw.

6. Fork & Bearing.

7. Clutch shaft.

I) Single plate clutch:

A single plate is commonly used in cars and light vehicles. It has only one clutch plate

which is mounted on the splines of the clutch shaft. A flywheel is mounted on the crankshaft

of the engine. A pressure plate is connected to the flywheel through the bolts and clutch

springs. It is free to slide on the clutch shaft with the movement of clutch pedal. When clutch

is in engaged position, the clutch plate remains gripped between flywheel and pressure plate.

Friction linings are provided on both the sides of clutch plate. On one side clutch plate is in

touch with flywheel and on other side with pressure plate. Due to friction on both sides, the

clutch plate revolves with engine flywheel. Therefore, clutch transmits engine power to


clutch shaft. Clutch shaft is connected to transmission (or gear box) of automobile. Thus,

clutch transmits power from engine to transmission system which inturn rotates wheels of

engine.

When the clutch plate is to be disengaged, the clutch pedal is pressed. Because

of this pressure plate moves back and clutch plate is disengaged from flywheel. Thus, clutch

shaft stops rotating even if engine flywheel is rotating. In this position, power does not reach

the wheels and vehicle also stops running. Single plate clutch is shown in Figure.

II) Multiplate clutch:

Multi-plate clutch consists of more than one clutch plates contrary to single plate

clutch which consists of only one plate. Friction surfaces are made in case of multi-plate

clutch. Due to increased number of friction surfaces, a multi-plate clutch can transmit large

torque. Therefore, it is used in racing cars and heavy motor vehicles which have high engine

power. The clutch plates are alternatively fitted with engine shaft and the shaft of gear box.

He plates are firmly held by the force of coil springs and they assembled in a drum. One plate

slides in the grooves on the flywheel and the next plate slides on spines provided on pressure

plate. Thus, each alternate plate slides in grooves on the flywheel and the other on splines of

pressure plate. If we take two consecutive plates, then one has inner and other has outer

splines.

When the clutch pedal is pressed, the pressure plate moves back against the force of

coil spring, when the clutch plates are disengaged and engine flywheel and gear box are

decoupled. However, when clutch pedal is not pressed the clutch remain in engaged position

and the power can be transmitted from engine flywheel to the gear box. This type of clutch

has been shown in Figure.

Clutch pedal free-play adjustment:

Clutch remains in engaged position when clutch pedal is not pressed. Free play

adjustment is required to maintain a given free play of the pedal after the clutch is engaged.

Before making this adjustment, correct floorboard clearance or clutch pedal travel must be

adjusted.

Floorboard clearance adjustment is made to prevent touching of floor by pedal when clutch is

engaged.

Clutch pedal travel adjustment is done to ensure total clutch disengagement when the

clutch pedal is pressed.


Component of clutch

i) Clutch plate.-

The clutch plate consist steel plate with a splined central hub. Annular friction facings are

attached to the steel plate by rivets, special resins are being used to bind friction facing.

ii) Clutch facing.-

The wear of clutch facing depends upon rubbing speed & intensity of press for maximum,

Life the rubbing speed at the time of engagement should not exceed 30 ms-1 while press

intensity should not exceed 100 kpa.

iii) Pressure plate:-

High tensile grey iron is the most commonly used material for pressure plate which must be

sufficiently rigid is as not distort under press of the clutch springs adequate rigidity is also

needed to provide uniform pressure to clutch plate.

iv) Release lever:-

The pressure plate in case of coil spring type clutch has a number of release levers usually

there of four especially spaced around the pressure plate.

v) Cover:-

This is a steel pressing bolted on to the flywheel & houses the pressure plate assembly

It provides pivot for the release levers & taken reaction of the springs due to which reason it

must be sufficiently rigid.

vi) Springs.:-

Normally, duty clutch springs are made from coil tempered spring steel wire however for

sever conditions they are made from silica chrome steel to prevent heat set insulating

washers are also sometimes used under extreme conditions to reduce heat conditions from

the pressure plate to springs.


Friction material:-

1. Leather: Dry leather on iron has coefficient in friction of 0.27.

2. Cork: Cork on dry steel friction or iron has coefficient of friction is 0.32.

3. Fabric: Good quality fabric materials have coefficient of friction is about 0.9. They

cannot use at high temperature.

4. Asbestos: Asbestos facing has coefficient of friction about 0.2; however it has got anti

heat characteristic.

Clutch plate:-

The clutch plate consists of steel plate with a splined central hub. Annular facings

(friction) are attached to the steel plate by rivets. The axial cushioning interposed between the

clutch plate & friction facings are riveted to these springs on engagement. The load applied

first has to compress the spring regiments to the flat condition resulting in a greater degree of

clutch control (due to longer distance traveled at the clutch plate) & therefore smooth

engagement.

The central hub sub- assembly consists of a splined hub with radially placed slots in the

flange of hub. There are similar slot in which coil springs under slight compression are fitted

these provide a flexible torsional connection between center hub flange and ride plates which

are riveted to main clutch plate.

Diaphragm clutch.

A diaphragm spring type clutch is shown in Fig (a) shows the clutch in the engaged

position and Fig. (b) In the disengaged position.

It is seen from the above figures that the diaphragm spring is supported on a fulcrum

retaining ring so that any section through the spring can he regarded as a simple \ever. The

pressure plate E is movable axially, but it is fixed radially with respect to the cover. This is

done by providing a series of equally spaced Jugs cast upon the back surface of the pressure

plate. The drive from the engine flywheel is transmitted through the cover, pressure plate and

the friction plate to the gear box input shaft.

The clutch is disengaged by pressing the clutch pedal which actuates the release fingers

by means of a release ring. This pivots the spring about its fulcrum, relieving the spring load

on the outside diameter, thereby disconnecting the drive.

Advantages of the diaphragm spring type clutch:-


1. This type of clutch has now virtually superseded the earlier coil spring design in

many countries in clutch sizes ranging up to 270 mm. in diameter, although in case of

heavy vehicles, the coil spring type clutches are still being used, because of the

difficulty to provide sufficient clamping force by a single diaphragm spring. The

diaphragm spring, however, offers certain distinct advantages.

2. It is a more compact means of storing energy. Thus compact design results in smaller

clutch housing.

3. As the diaphragm spring is comparatively less affected by the centrifugal forces, it

can withstand higher rotational speeds. On the other hand, coil springs have tendency

to distort in the transverse direction at higher speeds.

4. In case of coil springs, load-deflection curve is linear. Therefore with the wear of the

clutch facing the springs have less deflection due to which they would apply Jess

force against the clutch plate. On the other hand in case of diaphragm spring, the load-

deflection curve is not linear. Therefore, in this case, as the clutch facing wears, force

on the plate gradually increases, which means that even in the WOIn out condition,

the spring force is not Jess than its value in case of new.

5. The diaphragm acts as both clamping spring and release levers. Therefore, many extra

parts like struts, eye bolts, levers etc. are eliminated in the diaphragm spring, because

of which the loss of efficiency due to friction wear of these parts also does not occur.

which results in the elimination of squeaks and rattles.

Electromagnetic clutch

This type of clutch has been employed on some Renault cars. The construction and

working of this clutch may be understood by means of simplified Fig. A is the engine

flywheel incorporating the winding B. Clutch plate C is lined with friction surfaces and is free

to slide on splines on the clutch shaft. D is the pressure plate. The winding B is supplied with

current from battery dynamo. When the winding B is energized, it attracts the pressure plate

D, thereby engaging the clutch. When supply to winding B is cut off, the clutch is

disengaged.

There is a clutch release switch in the gear lever. This switch is operated as soon as

the driver holds the gear lever to change the gear, cutting off current to the winding and thus

causing clutch disengagement. Ordinarily the winding is connected to engine dynamo. At

lower engine speeds, dynamo output is also low which makes the force in winding very


small. Three rings are also provided in the clutch (not shown) to balance this reduced

electromagnetic force at low speeds, thus disengaging the clutch.

During normal operation, the electromagnetic force of the winding is regulated by

means of an electrical resistance, which itself is controlled by means of accelerator pedal. As

the acceleration pedal is pressed the resistance is gradually cut, thus increasing the

electromagnetic force. The electromagnetic type of clutch is best suited where remote

operation is desired since no linkages are required to control its engagement. A major

limitation of this type is that of heat capacity since the clutch-operating temperature is limited

by the temperature rating of the insulation of the magnetic coil. Another disadvantage is its

higher initial cost.


Experiment No. 03

Automobile Gear box.


EXPERIMENT NO - 3.

Title Automobile gear box.

Aim To study different types of gear box used in automobile.

Objectives -

To study function & requirement of gear box.

To study type of gear box.

To study construction & working of Synchromesh gear box.

To study synchronizing unit..

To demonstrate on Synchromesh gear box.

Introduction:-

Function of gear box

The main functions which are performed by the gear box are

1) The torque or tractive efforts produced by the engine varies with speed only within

narrow units limits butt the practical considerations for the running of automobile

under different condition of torque available at the wheels. The main purpose of gear

box is to provide a means of large variation in torque ratios between the engine &

transmission system.

2) The gear box also provides a natural position so that the engine & road wheels are

disconnected even with the clutch in the engaged position.

3) A means to back the car by reversing the direction of also provided by the gear box.


Necessity of gear box:

i. To provide variation in the torque.

ii. To provide variation of tractive effort of vehicle available at various speeds.

iii. To Provide reverse direction to the vehicle.

iv. To provide the idle condition i.e. disconnect engine from the transmission system.

Types of gear box:

Following are the type of gear box

1) Manually operated gear box.

a. Sliding mesh gear box

b. Constant mesh gear box.

c. Synchromesh gear box

2) Automatic operated gear box.

a) Fluid type gear box. b) Electric type gearbox.

3) Synchromesh Gear Box

This type of gear box is similar to const mesh with the corresponding gear on the lay shaft

the lay shaft are fixed to it while those on the main shaft are free to rotate on the same. Fig.

shows the construction & working of synchromesh gear box.

Construction

In Fig. A. is engine shaft gear B,C ,D,E. are free on the main shaft & are always in

mesh. With corresponding gears on the lay shaft as well as on lay shaft continue to rotate so

long as shaft A rotating Member F1 & F2 are free to slide on spines on the main shaft G1 & G2

Are ring shaped members having internal teeth Fit into the external teeth members F1 & F2

respectively K1 & K2 are dog teeth on B & D respectively & those also fit on to the teeth of

G1 & G2 & S1 & S2 are the fork T1 & T2 are the ball supported by spring . these tends to

prevent the sliding of members G1 (G2 ) on F1 ( F2 ). However When the force applied on G1

(G2 ) through fork slides over& S1 (S2 ) exceeds a certain value. The balls are overcome &

member G1 (G2 ) slides over F1 ( F2 ).there are usually six of these balls symmetrically


placed circumferentially in one synchromesh device , M1, M2, N1,N2 ,P1,P2, R1,R2 are

frictional surfaces.

Working --

For direct gear member G1 (through spring loaded balls) is slide towards left till cones

M1& M2 rub & friction makes their speed equal further pushing the member G1 to left causes

it to override the balls get engaged with dogs k1 now the drive to the main shaft is direct from

B via F1 & the splines. However, if member G1 is pushed too quickly so that there is not

sufficient time for synchronization of speeds a clash may result. Likewise defect will arise in

case springs supporting the balls if have become weak.

Similarly for second gear member F1 & G1 are slid to the right to that finally the

internal teeth on G1 are engaged with L1 . Then the drive to main shaft will be form B via U1

U2 C1 F1 & splines. For Fist gear G1 & F2 are moved towards left the drive will be form B

via U1, U3, D1, F2 & splines to the main shaft..

Synchromesh unit:

In synchromesh gear box it is very necessary for the smooth operation that

sufficient time is allowed for the equation of the speeds before the equalization of the speeds

before the gears are finally brought into mesh. To help in this special modification have been

Employed in many gear boxes one such modified synchromesh device is shown in provided

between the dog teeth K1 & member F1. to push this synchromesh ring in the desired direction

, there guide bar equally spaced along the circumference are provided. These are retained in

place by means of serclips teeths at its outer circumference & is cut at three places to

provide space for the guide bars plus half the pitch of the teeth on the synchronizer Ring.

When the gear is to be engaged, fork S1 side F1 to left pushing synchronizer

ring also Along till the inclined friction surface on the inside of the ring domes into contact

with the corresponding friction surface of the gear till the speeds of the two mating surfaces

have not equalized the guide bars would be contacting one side of the corresponding cuts in

the synchronizer ring as shown in fig In this position G1 cannot move further. However, as

the speeds are equalized, the guide bars become central in the cut & the member G1 can be

pushed further overriding the spring loaded balls as explained earlier so as to engage gear.


4) Constant mesh gear box:-

In this type of gear box, all the gears are in constant mesh with the

corresponding gears on the lay shaft. The gears on the main shaft, which is splined, are free.

The dog clutches are provided which are free to slide on the main shaft. The gears on the

layshaft are, however, fixed. When the left dog clutch is slid to the left by means of the

selector mechanism, its teeth are engaged with those on the clutch gear and we get the direct

gear. The same dog clutch, however, when slid to right makes contact with the second gear

and second gear is obtained. Similarly movement of the right dog clutch to the left result in

low gear and towards right in reverse gear.

Double Declutching:-

In the constant mesh box, for the smooth engagement of the dog clutches it is

necessary that the speed of main shaft gear and the sliding gear must be equal. Therefore to

obtain lower gear, the speed of the clutch shaft, layshaft and main shaft gear must be

increased. This is done by double clutching. The procedure of double clutching is given

bellow.

The clutch is disengaged and the gear is brought to neutral. Then the clutch is engaged

and accelerator pedal is pressed to increase the speed of the main shaft gear. After this the

clutch is again disengaged and the gear moved to the required lower gear and the clutch is

again engaged. As the clutch disengaged twice in this process, it is called double declutching.

Advantages:-

Compared to the sliding mesh type, the constant mesh gear box has the following

advantages.

1. As the gears have to remain always in mesh, it is no longer necessary to use straight

spur gears. Instead, helical gears are used which are quieter running.

2. Wear of dog teeth on account of engaging and disengaging is reduced because; here

all the teeth of the dog clutches are involved compared to only two or three teeth in

the case of sliding gear.

4) Sliding mesh type of gear box:-


This is simplest type of gear box. Figure shows simplified view of the gear box. The

power comes from the engine to the clutch shaft and thanes to clutch gear which is always in

mesh with the gear on the lay shaft. All the gear on the lay shaft is fixed to it and as such they

are all the time rotating when the engine is running and the clutch is engaged. Three direct

and one reverse speeds are attained on suitably moving the gear on the main shaft by means

of selector mechanism. The various positions are shown in figure.


Experiment NO - 4.

Final Drive And Differential.


EXPERIMENT NO - 4.

Title Final drive and differential.

Aim To study final drive and differential unit.

Objectives -

To study function & construction of propeller shaft.

To study function of final drive.

To study types of gears used in final drive.

To study construction & working of differential unit.

To study function & requirement of differential unit.

To demonstrate on differential unit.

Introduction:-

Propeller shaft:

Functions: - Function of propeller shaft is to transmit the drive from the transmission to the

bevel pinion or worm of final drive in front engine rear drive vehicles.

Construction:

Propeller shaft consist mainly three parts.

1. Shaft As this has to withstand mainly torsional loads it is usually mode of tubular

cross- sections.

2. Universal joint- One or two universal joint account for up & down movement of the

rear axle when the vehicle is running.

3. Slip joint Depending upon the type of drive, one slip joint may be there in shaft.

This serves to adjust the length of the propeller shaft when demanded by the rear axle

movements.

A propeller shaft has two universal joints at the ends and a slip or sliding

joints. Slip joint is formed by the internal splines on the sleeve attached to the `left universal

joint & external splines on the propeller shaft as shown.


Function:-

The function of the final drive is to provide a permanent speed reduction & also to turn

the drive through 900. The reduction provided is about 4:1 in case and 10: 1 in heavier

vehicles.

This is done either in one or two stages for lesser reduction say up to about 7:1 single

reduction are achieved in two steps. the double reduction has.

Final drive:

The functions of the final drive are to provide a permanent speed reduction and also to

turn the drive und through 90. The reduction provided is about 4: I in cars and 10: I in

heavier vehicles. This is done it her in one or two stages. For lesser reduction, say upto about

7:1 single reduction is used, while higher reductions are achieved in two steps. The double

reduction has to be resorted to, because otherwise the size f the larger gear becomes too

much.

The final drive in practice consists of a bevel pinion and a crown wheel or alternatively,

worm and wheel arrangement. The bevel pinion is mounted on a shaft which is connected to

the propeller shaft generally through a universal joint. From the crown wheel the drive goes

to the differential. Three types of gears are used for the final drive gearing:

1. Straight Bevel Gears

These contain the straight teeth. They are therefore simplest and thus the cheapest of

all types. However, with straight bevel gears, at one instant only one pair of teeth of pinion

and the crown wheel will be in contact. As a result an uneven transmission of motion will

take place as the load is transferred from one pair of teeth to the next. Thus these gears are

noisy and suffer from high wear.

2. Spiral Bevel Gears

The spiral bevel gears have curved teeth which result in greater contact of the teeth.

Because of this spiral bevel gears are silent running and stronger than the straight bevel gears

3. Hypoid Gears

These types of gears are widely used for final drive these days. The name 'hypoid' is

derived from the 'hyperboloid of revolution'. The basic surface on which the teeth are cut in

their case, is hyperboloid, which is a solid obtained by rotating a hyperbola about an offset

axis. Such gears are employed to connect shafts at right angles to each other, but not lying in

the same plane.


In appearance, the shape of the teeth is similar to the ones in case of spiral bevel gears.

Worm and wheel arrangement:

Apart from bevel pinions and the crown wheel, the worm and wheel arrangement is

also used quite frequently. Worms used are of the multi-start type. Such a worm would have a

lead equal to number of starts times its pitch and would thus advance the wheel through a

larger distance compared to a single start worm. This decreases the gear ratio. Usually

final drives have four to eight start worms depending upon the reduction required. Thus,

Differential:

The purpose of the differential assembly is to allow the two drive wheels to turn at

different speeds when the car goes around a corner. This is necessary because when

cornering, the wheel on the inside of the turn goes through a smaller arc or corner than the

wheels on the outside. If the wheels were not allowed to turn at different speeds, they would

tend to skip around the corner and steering would be very difficult.

Differentials are used in:

a) The rear drive axle of front engine, rear wheel drives vehicles.

b) The transaxles of front engine, front wheel drive and rear engine, rear wheel drive

vehicles.

c) The front drive axle and rear drive axle of four wheel drive vehicles.

d) The transfer case of some four wheel drive vehicles.

Both the front drive and rear drive differential have the same job to do. They also have

many of the same parts. The basic difference is the way in which engine torque is delivered to

the differential assembly.

Power enters the rear axle assembly from the final drive which consists of bevel

pinion connected through a rear universal yoke to the propeller shaft. The bevel pinion is

meshed with the crown wheel, which is bolted to the case. This arrangement allows the bevel

pinion to turn. The crown wheel. As the crown wheel turns, the case attached to it also turns.

A shaft through the case also goes through the middle of two small pinion gears. As the case

turns, this shaft turns the small pinion gears, each of which meshes with a side gear. Each

side gear is attached to a shaft called an axle, which on a rear drive system runs through

housing to one of the rear wheels. When the automobile is travelling in a straight line, the


power flow through the system is fairly simple. The crown wheel turns the case. The case,

through its shaft and pinion gears, turns each of the side gears at the same speed. The axles or

drive shafts turn the drive wheels, which drive the vehicle.

When the vehicle makes a turn, however, the power flow becomes more complicated. If the

automobile is making a left turn, the left drive wheel must go through a sharper corner or

travel through a shorter distance than the right drive wheel. The crown wheel turns the case.

Since the left wheel is going through a sharp corner, the left axle is slowed or stopped

momentarily. The pinion gears in the case still turn with the case but they also rotate on the

case shaft. Thus they can walk around the slowed or stopped left side gear and provide all the

power to the right side gear so the right wheel will turn faster than the left wheel.

During a right turn there is more resistance on the right axle, because the right wheel

must turn through a sharper corner than the left. The pinions in the case walk around the right

side gear and drive the left axle gear.


Experiment No. 05

Hydraulic Brake System


EXPERIMENT NO.:-5

Title: - Hydraulic brake system.

Aim: - To study hydraulic brake system.

Objectives:-

To study function & requirement of breaking system.

To study classification of braking system.

To study construction & working of hydraulic braking system.

To demonstrate on hydraulic breaking system.

Introduction:-

Brakes are one of the most important control components of vehicle. They are required

to stop the vehicle within smallest possible distance & this is done by converting the kinetic

energy of the vehicle into heat energy which is dissipated into the atmosphere.

Function and requirement of brake

a) To reduce the speed of the vehicle.

b) To keep the vehicle at rest.

c) To control the vehicle.

Requirement:-

a) It should be easy to operate.

b) It should easy to adjust.

c) The brake must be enough strong to stop vehicle within a minute distance in an

emergency.

d) The brakes must have good anti feed characteristics i.e their effectiveness should not

be decrease with constant prolonged application.

e) It should required minimum force to operate.

f) there are no skidding

Classification of brakes:-

The brakes for automotive use may classify according to the following consideration.

a) Purpose


b) Location.

c) Construction.

d) Method of actuation.

e) Extra braking effort.

Purpose:-

From this point of view brakes may be classified as service or primary & parking or

secondary brakes. The service brakes are the main brakes used for stopping vehicle while in

motion, whereas parking brakes are meant hold vehicle on a slope.

Location:-

The brakes may be located either on transmission or at wheels. firstly the locations of

transmission brakes from this view point very poor, whereas in case of wheel brakes may

have four brakes drum. i.e. one on each wheel.

Construction:-

From construction point of view, two categories are drum brakes & the disc brakes.

Method of actuation:-

This criterion gives the following brakes type.

a) Mechanical brake

b) Hydraulic brake

c) Electric brake

d) Vacuum brake

e) Air brakes

Extra braking effort:-

In this brakes are called servo brakes or power assisted brakes. however, when

practically none of breaking effort is applied by driver, brakes are termed power brakes or

power operated brakes.

Construction and working of hydraulic brakes:-

An outline of hydraulic braking system in fig. the main component in this is master

cylinder, which contain reservoir for the brake fluid. Master cylinder is operated by brakes

paddle and is further connected to wheel cylinder in each wheel through steel pipe lines and

flexible hoses. The system is so designed that even when brakes are in released position, a

small pressure of about 50 kpa is maintained in pipe lines to ensure that cups of wheel


cylinder are kept expanded. This prevents air from entering wheel cylinders when the brakes

are released. Besides, this pressure also serves following purpose.

i. It keeps free travel of peddle min. by opposing brake shoe retraction sprig.

ii. During bleeding, it does not allow fluid pumped into line to return, thus quickly

purging air from system. The main components of hydraulic braking system are as

follows:-

Master cylinder:-

This can be rightly named as heart of hydraulic braking system. There are two main

chambers viz. fluid reservoir & compression chamber in which piston operates. the fluid in

reservoir components for any change in fluid volume in pipeline due to temp. Variation & to

some extent due to leakage, to prevent leakage there are rubber seal on both side of piston in

compression chamber. The reduce diameter region of piston always surrounded by fluid. a

rubber but covers push rod end of master cylinder to prevent dirt from entering inside.

Towards the brake lines side of compression chamber, there is a fluid check valve with a

rubber cup inside. It serves to retain residual pressure in brakes line even when brakes are

released.

There is a no. of holes in piston head on primary seal side. Two holes connect fluid

reservoir to compression chamber. The smaller one out of these is about 0.7mm dim. It is

called bypass or compression port. The second hole is called intake or recuperation on port.

As pedal is pressed, push rod moves piston to left against force of spring till it cover

bypass port. Finally when sufficient pressure has built up inner rubber cup of fluid check is

deflected, forcing the fluid under pressure in lines. This fluid enters wheel cylinder or caliper

& moves the piston thereby applying brakes.


Tandem master cylinder:-

Tandem master cylinder ensures reliability with not much extra cost. Under ordinary condition brake fluids will transmit pressure both to as well as to the rear brakes when brake pedal is applied. however, the front brake lines are damaged piston(2) will move till come up in space between piston 1&2 & rear, brakes will be applied similarly when rear brake lines or damaged, no pressure will built up in space between piston 1&2. So piston (1) will move freely till it comes up against (2). Further push at brake pedal will move both piston (1) & (2) together there by applying the front brakes.

Wheel cylinder:-

Wheel cylinder in brake system is meant to force brake shoes against the

drum. Each wheel cylinder is provided with piston, rubber seals (cups), cup spreaders, spring

& dust covers (boots). The brake line from the master cylinder is attached to the inlet part & a

bleeder screw with a cover is provided to bleed air from system whenever required. Wheel

cylinders are mounted on the back plate.

When are applied the fluid under pressure from master cylinder enters at inlet

part & forces against drum. Similarly, when brake is released, brake shoe retractor spring

forces brake fluid out the wheel cylinder by pushing piston inward.

Advantages and disadvantages of hydraulic brakes

Advantages:

(a) Equal braking action on all wheels.

(b) Increased braking force.

(c) Simple in construction.

(d) Low wear rate of brake linings.

(e) Flexibility of brake linings.

(f) Increased mechanical advantage.

Disadvantages:

(a) Whole braking system fails due to leakage of fluid from brake linings.

(b) Presence of air inside the tubings ruins the whole system.

Braking systems:


Air Brakes

Air brakes are applied by the pressure of compressed air. Air pressure applies force on

brakes shoes through suitable linkages to operate brakes. An air compressor is used to

compress air. This compressor is run by engine power.

Vacuum Brakes

Vacuum brakes are a piston or a diaphragm operating in a cylinder. For application of

brakes one side of piston is subjected to atmospheric pressure while the other is applied

vacuum by exhausting air from this side. A force acts on the piston due to difference of

pressure. This force is used to operate brake through suitable linkages.

Electric Brakes

In electrical brakes an electromagnet is used to actuate a cam to expand the brake

shoes. The electromagnet is energized by the current flowing from the battery. When flow of

current is stopped the cam and brake shoes return to their original position and brakes are

disengaged. Electric brakes are not used in automobiles as service brakes.


Experiment No. 06

Study and demonstration of front wheel steering geometry

and steering mechanism.


EXPERIMENT NO 6.

Title Study and demonstration of front wheel steering geometry and steering mechanism.

Aim To of front wheel steering geometry and steering mechanism..

Objectives:-

1. To study functions & requirement of steering.

2. To study correct steering, under steering & over steering conditions.

3. To study steering linkage for independent of rigid axle suspension for front wheel.

4. To study steering gear.

5. To demonstrate on steering mechanism.

Introduction:

Primary function of steering system is to achieve angular motion of the front wheel to

negotiate the turn .This is done through linkage of steering gear which convent the rotary

motion of system steering wheel into the angular motion of the front wheels.

Function:

1. To provide directional stability of the vehicle when going straight ahead.

2. To provide perfect steering condition i.e. perfect rolling motion of road wheels at

all times.

3. The facilities straight ahead recovery after completing turn.

4. To minimize turn wear.

Requirements:

1. The steering mechanism should be very accurate & easy to handle.

2. The effort required to steer should be minimum & must not be tiresome to the driver.

3. The steering mechanism should also provide directional stability.


Vehicle dynamics and steering:

Generally speaking, when you turn the steering wheel in your car, you typically

expect it to go where you're pointing it. At slow speed, this will almost always be the case

but once you get some momentum behind you, you are at the mercy of the chassis and

suspension designers. In racing, the aerodynamic wings, air splitters and undertrays help

to maintain an even balance of the vehicle in corners along with the position of the weight

in the vehicle and the suspension setup. The two most common problems you'll run into

are understeer and oversteer.

Correct steering:

The perfect steering is achieved when all the four wheels are rolling perfectly under

all conditions of running, while taking turns the condition of perfect rolling is satisfied it the

axes of the front wheel axes at one point. Then this point is instantaneous centre of the

vehicle. It is seen that inside vehicle is required to turn the greater angle than outer wheel.

The larger the steering angle of inner wheel can have maximum value of about 440 the

extreme position. The diameter of the smallest circle which the outer front wheel they can

transverse & obtained when the wheels are at their extreme position is called as running

circle.

Understeer:

Understeer is so called because the car steers less than you want it to. Understeer

can be brought on by all manner of chassis, suspension and speed issues but essentially it

means that the car is losing grip on the front wheels. Typically it happens as you brake

and the weight is transferred to the front of the car. At this point the mechanical grip of

the front tyres can simply be overpowered and they start to lose grip (for example on a

wet or greasy road surface). The end result is that the car will start to take the corner very

wide. In racing, that normally involves going off the outside of the corner into a catch

area or on to the grass. In normal you-and-me driving, it means crashing at the outside of

the corner. Getting out of understeer can involve letting off the throttle in front-wheel-

drive vehicles (to try to give the tyres chance to grip) or getting on the throttle in rear-

wheel-drive vehicles (to try to bring the back end around). It's a complex topic more

suited to racing


driving forums but suffice to say that if you're trying to get out of understeer and you

cock it up, you get.....

Oversteer:

The bright ones amongst you will probably already have guessed that oversteer is

the opposite of understeer. With oversteer, the car goes where it's pointed far too

efficiently and you end up diving into the corner much more quickly than you had

expected. Oversteer is brought on by the car losing grip on the rear wheels as the weight

is transferred off them under braking, resulting in the rear kicking out in the corner.

Without counter-steering (see below) the end result in racing is that the car will spin and

end up going off the inside of the corner backwards. In normal you-and-me driving, it

means spinning the car and ending up pointing back the way you came.

Counter-steering:

Counter-steering is what you need to do when you start to experience oversteer. If you get

into a situation where the back end of the car loses grip and starts to swing out, steering

opposite to the direction of the corner can often 'catch' the oversteer by directing the nose

of the car out of the corner. In drift racing and demonstration driving, it's how the drivers

are able to smoke the rear tyres and power-slide around a corner. They will use a

combination of throttle, weight transfer and handbrake to induce oversteer into a corner,

then flick the steering the opposite direction, honk on the accelerator and try to hold a

slide all the way around the corner. It's also a widely-used technique in rally racing. Tiff

Needell - a racing driver who also works on some UK motoring programs - is an absolute

master at counter-steer power sliding.


Steering system for right axle front suspension:

Fig Shows a rigid axle steering linkage the drop arm is rigidly connected to the c/s

shaft of the steering gear at its upper while its lower end is connected to the link rod the ball

joint to the outer end of the link rod is connected to arm through a ball joint . Each stud axle

has a forged track rod arm rigidly bolted to the wheel axis .The other end of track rod arm are

connected to track by means of ball joints. The design of their ball joints is such that the

expanding spring compensation for wear or miss adjustment .An adjustor is provided in the

track rod to change its length for adjusting the wheel alignment.

Steering linkage with independent suspension:-

In this there is no vertical deflection of the suspension hence there is no change in

effective track rod length, however in case of independent suspension the two stud axle can

move up or down independent on each other due to which distance between ball joint end of

the two track rod arm is continuously varying an account of this a single track rod as

conventional system described above cant be used.

The fig. depicts are linkage for the independent suspension where the above difficulty

is avoided .there 3 piece track rod is used .the centre position being called the really rod

which is supported on body & to drop arm of the steering gear at the other end through ball

joints .

Steering gears:

The steering gear converts the turning motion of the steering wheel into the to & fro motion

of the link rod of the steering linkage .It also provides the necessary leverage so that the

driver is axle steer the vehicle without fatigue.

There are 5 types of steering gears which are as follows.

1. Worm & worm wheel steering gear

2. Worm & nut steering gear.

3. Worm and roller steering gear.

4. Recalculating ball type steering gear.

5. Rack and pinion steering gear.


Worm & worm wheel steering gear:

The movement of the steering wheel turns the worm with in turn drives the wheels

attached to the wheel spindle rigidly is drop arm , so that a rotation of steering wheel

corresponds to a linear motion of the drop arm end , which is connected to the link rod as has

already been discussed .

In place of worm wheel only a sector is also sometimes used but the complete wheel has an

advantage over the latter in that case back lash due to wearing out of the teeth of the worm &

worm wheel can be easily adjusted for its purpose the worm wheel is mounted over an

eccentric bush. When the teeth have worm out the problem it how to bring the worm & worm

wheel together to take up wear .This is done by rotating the bush there certain angle.

Worm & Nut steering gear:

The construction of this type of gear is as shown. In this system when the steering

wheel is rotated the steering columns rotates. The worm is an integrated part of the steering

column. Therefore when the steering column rotates, the worm also rotates. Now the worm is

mesh with a nut arrangement. This movement will take place along the axis of the column

eighter up or down. This enables the cross shaft to rotate in an arc. This arm transmits the

steering to all wheels.

Worm and roller steering gear:

In this system the worm is at the end of steering column. The diameter of worm is

more at its ends. Its diameter is gradually reduced at the centre. A roller is in mesh with this

worm. The roller has a cross shaft which is fitted to drop arm.

When steering wheel is rotated, the column also rotates. Also, when the worm of the

shaft is rotated, the roller rotates in an arc. Which is turn rotates the wheel.

Recirculation ball type steering gear:

It consists of a worm at the end of steering rod/shaft. A nut is mounted on the worm

with two sets of balls in the grooves of the worm, in between the nut and the worm. The balls

reduce the friction during the movement of the nut on the worm. The nut has number of teeth

on the outside, which mesh with the teeth on a worm wheel sector, on which is further

mounted the drop arm, which steers the road wheels through link rod and steering arms.


Rack and pinion steering gear:

A pinion is mounted on the end of steering shaft. It engages with a rack which has ball

joints at each end to allow for the rise or fall of the wheels. As the pinion teeth mesh with

rack teeth, rack moves to and fro. A rack and pinion steering gear is suitable for small cars

where steering force is light.


Experiment No. 07

Study and demonstration of suspension system of a four-wheeler.


EXPERIMENT NO. :-7

Title: - Study and demonstration of suspension system of a four-wheeler.

Aim: - To study suspension system.

Objectives:-

To study function & requirements of suspension system.

Type of suspension system.

To study leaf spring & shock absorber.

To study independent suspension system for front & rear wheel.

To demonstrate on suspension system.

Function of system:-

1. To prevent the road shocks from being transmitted to vehicle components.

2. To safeguard the occupants from road shocks.

3. To preserve stability of vehicle in pitching or rolling, while in motion.

Requirements of suspension system:-

1.Verticle loading :-

The frequency of the front springing system should be less than that of rear springing

system.

2.Rolling :-

To obviate the tendency for vehicle to roll, a stabilizer called anti-roll should be used in

the form of torsion bar.

3.Side thrust:

Centrifugal force during cornering ,cross winds, cambering of road etc. cause a side

thrust such forces are usually absorbed by rigidity of leaf spring.

4.Unsprung weight :-

The weight of the unsprung parts should be minimum to avoid vibration & shocks.

The suspension system should be optimum compromise between softness & hardness.


Principles of Suspension:

The suspension system isolates the body from road shocks and vibrations which would

otherwise be transferred to the passengers and load. It also must keep the tyres in contact with

the road. When a tyre hits an obstruction, there is a reaction force. The size of this reaction

force depends on the unsprung mass at each wheel assembly. The sprung mass is that part of

the vehicle supported by the springs- such as the body, the frame, the engine, and associated

parts. Unsprung mass includes the components that follow the road contours, such as wheels,

tyres, brake assemblies, and any part of the steering and suspension not supported by the

springs. Vehicle ride and handling can be improved by keeping unsprung mass as low as

possible. When large and heavy wheel assemblies encounter a bump or pothole, they

experience a larger reaction force, sometimes large enough to make the tyre lose contact with

the road surface. Wheel and brake units that are small, and light, follow road contours

without a large effect on the rest of the vehicle. At the same time, an uspension system must

be strong enough to withstand loads imposed by vehicle mass during cornering, accelerating,

braking, and uneven road surfaces.

Types of suspension system:-

The various springs may be classified as follows:-

1.Steel springs:-

a. Leaf spring. b. Tapered leaf spring. c. Coil spring d. Torsion bar.

2. Rubber spring:-

a. Compression spring. b. Compression shear spring c. Steel reinforced spring.

d. Progressive spring. e. Face shear spring. f. Torsional shear spring.

3. Plastic spring.

4. Air spring.

5. Hydraulic spring.

a) Leaf spring:-

Semi-elliptical leaf springs are almost universally used for suspension in light &

heavy commercial vehicles for cars also; these are widely used for suspension.

Construction:-


Fig. gives rear axial leaf spring of semi-elliptical type. The springs consist of no. of

leaves called blades. The blades vary in length as shown. The composite spring is based upon

theory of beam of uniform strength. The lengthiest blade has eyes on its ends. This blade is

called master leaf. All the blades are bound together by means of steel straps as shown.

The spring is supported on axel, front or rear by means of u-bolt. One end of the

spring is mounted on spring with simple while on other end; connection is made with a

shackle when the vehicle comes across a projection on road surface, the wheel moves up,

deflecting spring. This changes the length between spring eyes. If both ends are fixed, spring

will not able to accommodate this change of shackle at one end which gives a flexible

connection.

Shock absorber:-

A springing devise must be compromise between flexibility & stiffness. if it is more

rigid ,it will not absorb road shocks efficiently & if it is more flexible it will continue to

vibrate even after bump has passed. So we must have sufficient damping of spring to prevent

excessive flexing.

as shown in fig. rod g is attached to two ways valve a ,while another similar two

way valve b is attached at lower space between cylinder c & tube d ,which is connected to

space below valve assembly b as shown. h is gland in head j & any fluid scrapped passage

shown in the head , off by rod g is brought down into the annular space through inclined

passage, the eye e is connected to the axel, while the eye f is attached to chassis frame. The

fluid generally used n shock absorber is a mixture of 60% transformer oil & 40% turbine oil.

When car has more across a bump then eye e would up & there fluid will pass from

lower side of valve assembly to its upper side. But since volume of space above is less by

volume of rod g, fluid will also exert a pressure on valve assembly b & go to underside of

valve b. These passings of fluid through valve opening provide damping. Similarly for

downward motion, fluid will pass from upper side of the valve assembly to lower side & also

from lower side of valve assembly b to its upper side.

Independent suspension system (front wheel):-

One of the main benefits claimed for independent suspension is that unsprung

mass can be kept low. Also, if a wheel on one side hits a road irregularity, it wont upset

the wheel


on the other side on the same axle. And it allows wheel camber to be adjusted

individually, when provided for by the manufacturer. One of the simplest and most common,

independent suspension systems are the McPherson strut type. It can be used on the front and

rear of the vehicle.

Five type of independent suspension system .

1. Wishbone type or parallel link type.

2. Mac pherson strut type.

3. Vertical guide type.

4. Trailing link type.

5. Swinging half axle.

Wishbone type suspension:-

Fig. shows a diagrammatic sketch of wishbone type suspension with coil spring in

front axle suspension of cars is almost universal.

It consist of upper & lower wishbone arm pivoted to frame member, the spring is

placed between lower wishbone & the underside of cross-member. The

Body & cross member to coil spring through which it goes to the lower wishbone member.

shock absorber is placed inside the coil spring & is attached to cross member & to lower

wishbone arm are like the chicken. The wishbone arms are or letter v is shape, because of

which the system is so called. The wishbone type is the most popular independent system.

Macpherson strut front Suspension

The MacPherson strut suspension system is similar to the SLA suspension. The

MacPherson strut eliminates the upper control arm and mounts a coil type spring over the

strut assembly. TheMacPherson strut is used on most current front-wheel drive vehicles with

independent front suspensions. The suspension system consists of a lower control arm, a

vertical strut with a coil spring, and a sway bar. A strut rod or link is used to control fore and

aft movements if a lower control arm does not do this. The MacPherson strut contains

upper/lower spring seats and ashock absorber for damping spring oscillations. The coil spring

is offset on the strut to improve durability and reduce friction.

An isolator is located on the top of the strut. The isolator bolts to the upper fender

well reinforcement (strut tower) with several bolts. The isolator contains a pivot bearing that

allows the strut, steering knuckle, and wheel to turn.


Rear wheel (live axle) independent suspension:-

Through the rear wheels are not to be steered, yet there is considerable difficulty in

rear wheel. But even rear wheel independent springing is coming into prominence because of

its distinct advantages over axle type.

fig. shows the one method of rear wheel independent suspension universal coupling

a & b keep the wheel vertical , while sliding coupling c is required to maintain wheel track

constant, thereby avoiding scrubbing of types. This method has been used in de dion type of

axle

Telescopic type Shock Absorber

A 'Telescopic' shock absorber derives its name from the tubular shape of early

telescopes used in ancient times. These are of two types, viz., the mono-tube type and the

twin-tube type. Referring to Fig. wherein a twin-tube type shock absorber is shown, rod G is

attached to the two-way valve A; whiling other similar two-way valve B is attached at the

lower end of cylinder C. There is a fluid in the space below valve assembly A, below B and

also in the annular space between cylinder C and tube D, which is connected to the space

below the valve assembly B as shown. H is gland in the head J and any fluid scrapped off by

rod G is brought down into the annular space through the inclined passage shown in the head.

The eye E is connected to the axle, while the eye F is attached to the chassis frame. The fluid

generally used in shock absorbers is a mixture of 60 per cent transformer oil and 40 per cent

turbine oil.

To understand the action of the shock absorber, consider that the vehicle has come

across a bump. Then eye E would move up and there by the fluid will pass from the lower

side of valve assembly A to its upper side. But since the volume of the space above A is less

by the volume of rod G, the fluid will also exert its pressure on vale assembly B and go to the

underside of valve B. This passing of fluid through valve openings provides the damping.

Similarly for the downward motion of the eye E during rebound, the fluid will pass from the

upper side of valve assembly A to the lower side of valve assemble B.

Stabilizer Bar:

Stabilizer is necessarily used in all independent front suspension. It reduces tendency

of the vehicle to roll on either side when taking a turn. It is simply a bar of alloy steel with

arms at each end connected to the lower wish bone of the independent suspension system. It

is supported in bush bearings fixed the frame and is parallel to cross member. When both the


wheels deflect up or down by the same amount, the stabilizer bar simple turns in the bearings.

When only one wheel deflects, then only one end of the stabilizer moves, thus it acts as a

spring between two sides of the independent front suspension.

Torsion Bar

Torsion bar suspension is used in independent suspension system. It is a rod acting in

torsion and taking shear stresses only. It is made up of heat treated alloy spring steel. This bar

stores amount of energy nearly as same as coil spring. The bar is fixed at one end to the

fr4ame, while the other end is fixed to the end of the wheel arm and supported in the bearing.

The other end of the wheel arm connected to the wheel hub. When the wheel strikes a bump,

it starts vibrating up and down, thus exerting torque on the torsion bar which acts as a spring.

Trailing-arm rear suspension:

In order to minimize the amount of room required, the coil spring and monotube gas-

pressure shock absorber are directly supported by the chassis subframe. The connecting tube

is stress optimized oval shaped in order to withstand the high bending moments from

longitudinal and lateral wheel forces which occur in the course of driving. The torsionbar

stabilizer proceeds directly from the shock-absorber attachment for reasons of weight and

ease of assembly.

When establishing the spring/shock-absorber properties,the line along which the

forces act and which is altered by the lift of the wheel is to be taken into consideration, as a

disadvantageous load-path can occur with jounce. The two front subframes are hydraulically

damped in order to achieve a good level of comfort (hydromounts). The chassis subframe can

make minor elastokinematic control movements. When designing subframe mounts, it is

necessary to ensure that they retain their defined properties with regard to strength and

geometry even with unfavourable conditions of use (e.g. low temperatures) and for a

sufficiently long period of time,

because variations in the configuration have a direct effect on vehicle performance. The

longitudinal arms which run on tapered-roller bearings and which are subject to both flexural

as well as torsional stress are designed in the form of a parallelogram linkage. In this way, the

inherent disadvantage of a trailing arm axle - unwanted toe-in as a result of the deformation

of the link when subject to a lateral force - is reduced by 75%, according to works

specifications.

Airsuspension:


Air suspension system are designed to cushion the ride and keep the car, bus or truck

level fore and aft and at a constant height regardless of load. Air suspension was introduced

on many luxury cars in the late 1950s, but it was dropped after one or two model years.

Recently, however, new leveling systems have been researched and developed for passenger

car use, including air adjustable rear shock absorber.

A typical air suspension system consists of an engine-driven air compressor, supply tank,

filter or condenser, valves, piping, controls and air springs or bellows. In operation, the air

compressor maintains a constant pressure in the supply tank. Air is piped to the control

valves, which feed air to each spring as needed. Pressure is automatically increased on either

side or at front or rear as required to keep the car level and to keep any desired height from

the road (within limit of system).


Experiment NO.8

Study And Demonstration Of Battery, Electrical Charging System


EXPERIMENT NO 8.

Title Study and demonstration of battery, Electrical charging system.

Aim To study of battery and electrical charging system. Objectives -

To study battery function.

To study construction of battery.

To study cell theory of battery.

To study battery charging operation.

To study Alternator.

To study voltage regulator.

Introduction:-

The Automotive Battery:

A lead-acid storage battery is an electrochemical device that produces voltage and

delivers electrical current. The battery is the primary "source" of electrical energy used in

vehicles today. It's important to remember that a battery does not store power, but rather it

stores a series of chemicals, and through a chemical process power is produced. Basically,

two different types of lead in an acid mixture react to produce an electrical pressure called

voltage. This electrochemical reaction changes chemical energy to electrical energy and is the

basis for all automotive batteries.

The purpose of the battery:

The battery supplies power when the:

A) Engine is off: power from the battery is used to operate lighting, accessories, or other

electrical systems when the engine is not running.

B) Engine is starting: power from the battery is used to operate the starter motor and to

provide current for the ignition system during engine cranking. Starting the car is the

battery's most important function.


C) Engine is running: power from the battery may be needed to supplement the charging

system when the vehicle's electrical load requirements exceed the charging system's

ability to produce power. Both the battery and the alternator supply power when demand

is high.

Batteries - primary or secondary:

batteries can either be a primary cell, such as a flashlight battery once used, throw it

away, or a secondary cell, such as a car battery (when the charge is gone, it can be

recharged).

Primary cell: because the chemical reaction totally destroys one of the metals after a period

of time, primary cells cannot be recharged. Small batteries such as flashlight and radio

batteries are primary cells.

Secondary cell: the metal plates and acid mixture change as the battery supplies voltage. as

the battery drains the metal plates become similar and the acid strength weakens. This

process is called discharging. By applying current to the battery in the reverse direction, the

battery materials can be restored, thus recharging the battery.

Battery construction:

An automobile battery contains a diluted sulfuric acid electrolyte and positive and

negative electrodes, in the form of several plates. Since the plates are made of lead or lead-

derived materials, this type of battery is often called a lead acid battery. A battery is separated

into several cells (usually six in the case of automobile batteries), and in each cell there are

several battery elements, all bathed in the electrolyte solution.

Specific gravity of electrolyte:

Specific gravity means exact weight. A "Hydrometer" or a "Refractometer" compares

the exact weight of electrolyte with that of water. Electrolyte in a charged battery is stronger

and heavier than electrolyte in a discharged battery. By weight, the electrolyte in a fully

charged battery is about 36% acid and 64% water. The specific gravity of water is 1.000, and

the specific gravity of sulfuric acid is 1.835, which means the acid is 1.835 times heavier than

the water. The battery electrolyte mixture of water and acid has a specific gravity of 1.270

and is usually stated as "twelve and seventy."


Components of Battery:-

1) Battery case:

The battery case holds the electrolyte and the individual battery cell elements. It is

divided into six compartments or cells. The plates are raised up off the bottom of the case

with ribs to prevent them from shorting out if any of the active materials (lead, etc.) should

happen to fall from the plates. The case is made of polypropylene, hard rubber, and plastic

base materials. Some battery manufacturers use translucent plastic cases which allow

checking electrolyte level without removing vent caps. These cases often have "upper" and

"lower" electrolyte level markers on the outside of the case.

2) Vent caps:

Vent caps cover the holes that are used for adding electrolyte. They are also designed

to separate the sulfuric acid mist and the hydrogen gas that forms when the battery charges.

The caps are designed to the sulfuric acid mist to condense and drop back into the battery and

allow hydrogen gas to escape through the vent holes to the atmosphere.

Vent caps can cover each individual cell as shown below. Note:Many Gel Cell

Batteries use a one way check valve enplane of vents.

3) Vent cap strips:

Most batteries today use vent cap strips that cover multiple cells (shown below). The

caps are designed to allow hydrogen gas to escape and sulfuric acid mist to condense and

drop back into the battery.

Battery terminal identification:

Battery terminals are identified as either positive" or negative". Battery cases are

marked with a " + " for the positive terminal, and a " -" on the negative terminal as shown

below. The words POS " or " NEG" are often used instead of the + or -. On top post

terminal batteries, the positive post is slightly wider than the negative terminal post. This

allow for easy identification.


Battery charging System:

The battery, starting and charging systems are interrelated by a continual cycle of

converting chemical energy to mechanical energy and then back again. The starter motor uses

mechanical energy to crank the engine and once the engine is running, it's really a merry-go-

round sort of relationship. The rotation of the engine drives the alternator, forcing electrical

energy (current) into a battery, where it's stored as chemical energy. The chemical energy of

the battery is then changed back to electrical energy when it supplies current to the starter

motor and accessories. The cycle repeats itself as the engine's mechanical energy again drives

the alternator to recharge the battery so it can supply more current to the starter when needed.

Charging System Components:

Starter motor Alternator Voltage regulator Battery

Charging indicator

Starter Motor:

The starter motor is a powerful electric motor, with a small gear (pinion) attached to

the end. When activated, the gear meshes with a larger gear (ring), which is attached to the

engine. The starter motor turns the engine over to start the engine. When the engine starts

to spin faster than the starter, the starter automatically disengages.

Alternator:

The alternator contains these main components:

Stator (attached to alternator housing, remains stationary)

Rotor (spins inside the stator)

Rectifier

Voltage regulator

Slip rings and brushes make an electrical connection to the spinning rotor. The alternator

generates power through these steps:


Engine power drives the alternator rotor through a pulley and drive belt.

The alternator rotor spins inside the windings of the stator.

The stator windings generate an alternating current.

Rectifier diodes change the alternating current (AC) into direct current (DC).

Voltage Regulator:

The voltage regulator controls the alternators output current to prevent overcharging and

undercharging of the battery. It does this by regulating the current flowing from the battery

to the rotors field coil. Todays IC voltage regulator is a fully electronic device, using

resistors and diodes.

Charging Indicator:

The charging indicator is usually an ON/OFF warning lamp. When the system is running, the light should be OFF. The lamp lights when the charging system is not providing sufficient charge.

The charging indicator lights when the charging system is not supplying enough power to charge the battery.

Visual inspection of the battery.-

Battery maintenance should alwaysbegin with a thorough visual inspection.

Look for signs of corrosion on or around thebattery, signs of leakage, a cracked case

or top, missing caps, and loose or missing hold-down clamps. Checking electrolyte

level and adding water.- on vent cap batteries, the electrolyte level can be checked by

removing the caps. Some batteries have a fill ring which indicates the electrolyte

level. The electrolyte should be even ith the fill ring. If there is no fill ring, the

electrolyte should be high enough to coverthe tops of the plates. Some batteries have

an electrolyte-level indicator (delco eye).this gives a color code visual indication of

the electrolyte level, with black indicatingthat the level is okay and white meaning a

low level.

If the electrolyte level in the battery is low, fill the cells to the correct level

with distilled water (purified water). Distilled water should be used because it does not

contain the impurities found in tap water. Tap water contains many chemicals that


reduce battery life. The chemicals contaminate the electrolyte and collect in the

bottom of the battery case. If enough contaminates collect in the bottom of the case,

the cell Plates short out, ruining the battery. If water must be added at frequent

intervals, the charging system may be overcharging the battery. A faulty charging

system can force excessive current into the battery. Battery gassing can then remove

water from the battery. Maintenance-free batteries do not need periodic electrolyte

service under normal conditions. It is designed to operate for long periods without loss

of electrolyte.


Experiment NO.9

Study And Demonstration Of Electrical Starting System

Yadav Rahu

automobile laboratory manual (be)

Documents

performance of students

students activity

related skills

assessment teacher

laboratory manual

intellectual skills

motor skills

respective skills