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VOCATIONAL TRAINING REPORT

MARUTI SUZUKI SERVICE CENTER

SKY AUTOMOBILES

RAIPUR

Submitted by: College:

Saket Tiwari NIT Raipur

Ajay Agrawal

Manish Dev

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ACKNOWLEDGEMENT

With profound respect and gratitude, I take opportunity to convey my thanks to HR

Department of Sky Automobiles for permitting me to complete my training in the Service

Centre and to be the part of this esteemed organization.

I‟m extremely grateful to all the technical staff of Sky Automobiles for their co-operation and

guidance that has helped me a lot during the course of training. I have learnt a lot under them

and I will always be indebted to them for this value addition in me.

At last I would like to convey my thanks to all the members of the workshop who have

helped me at every stage of training and I am are forever indebted to the omnipotent and to

my parents for their cheerful encouragement, unfailing patience and consistent support.

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CONTENTS

1. INTRODUCTION

2. CHASSIS

3. FRAME INTEGRAL FRAME OR FRAME-LESS CONSTRUCTION

4. SUSPENSION SYSTEM FUNCTIONS OF SUSPENSION SYSTEM

LEAF SPRINGS

COIL SPRINGS

SUSPENSION TYPES – DEPENDENT HOTCHKISS DRIVE

INDEPENDENT

5. STEERING SYSTEM

6. TRANSMISSION

CLUTCH

PRINCIPLE OF CLUTCH

MAIN PARTS OF A CLUTCH

FUNCTION OF GEAR BOX

7. ANTI-LOCK BRAKING SYSTEM

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INTRODUCTION The automobiles such as cars, buses and trucks, etc. are generally considered to be consisting

of two major assemblies, chassis and body.

Automobile repairing and servicing is a most commonly known activity in almost all

urban areas where all types of motor vehicles like cars, buses, lorries, jeeps, etc. are

given for service and repairs. Regular maintenance and servicing of vehicles is

required for safe driving and durability of the vehicles. Improper maintenance of vehicles,

present conditions of roads, irresponsible driving, using cheaper spare parts, etc. are the main

reasons to send the vehicles for repairs and maintenance. Service station is the most essential

unit to vehicle users. This unit can be established in urban, semi-urban and village are to meet

the local requirement. Candidates having good experience or qualified persons can start this

unit with low investment.

There is good demand for automobile service centre due to increase in the number of vehicles

day to day. After implementation of globalisation and privatisation, many Multi-national

companies competing with each other and introduced many models of4-wheelers and 2-

wheelers. Besides, the purchasing power of the people also increasing considerably and it

becomes fall under necessary item in the cities/urban areas especially for business persons

and salaried persons. Now a days, the middle class persons are also maintaining 4-

wheelers/2-wheelersdue to affordable price and changing habits of the consumers. Hence,

there is a good demand for setting up of automobile servicing and repairing units particularly

in some important tribal centres.

CHASSIS

Chassis is a French term which is now denotes the whole vehicle except body in case of

heavy vehicles. In case of light vehicles of mono construction, it denotes the whole vehicle

except additional fittings in the body.

“Chassis consists of engine, power train, brakes, steering system and wheels mounted on a

frame”.

FRAME

The frame is the main part of the chassis on which remaining parts of chassis are mounted.

The frame should be extremely rigid and strong so that it can withstand shocks, twists,

stresses and vibrations to which it is subjected while vehicle is moving on road. It is also

called underbody.

The frame is supported on the wheels and tyre assemblies. The frame is narrow in the front

for providing short turning radius to front wheels. It widens out at the rear side to provide

larger space in the body.

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Integral Frame or Frame-less Construction

This frame is generally used in modern day automobiles including Maruti-Suzuki. In this type

of construction, there is no frame. It is also called unitized frame-body construction. In this

case, the body shell and underbody are welded into single unit. The underbody is made of

floor plates and channel and box sections welded into single unit. This assembly replaces the

frame. This decreases the overall weight compared to conventional separate frame and body

construction.

SUSPENSION SYSTEM

The frame and body of an automobile are mounted on front and rear axles through springs

and shock absorbers. If it is mounted directly on axles, all the socks and vibrations will be

transmitted to body causing discomfort to the passengers. The springs and shock absorbers

are used to damp the shocks and vibrations. The suspensions system includes all those parts

which are used to perform the damping action. Besides, springs and shock absorbers, a

suspension system includes other mountings also. The suspension system of a vehicle is

divided into front suspension and rear suspension.

FUNCTIONS OF SUSPENSION SYSTEM

(a) The main function of a suspension system is to prevent the socks to transmit to car or

vehicle body so that passengers may ride comfortably.

(b) To maintain the stability of vehicle during pitching and rolling actions while the vehicle is

in motion.

(c) To provide better road holding at the time of driving, braking and cornering.

(d) To allow proper steering geometry.

LEAF SPRINGS

Leaf Springs are used in rear suspensions in vehicles such as Maruti-Suzuki Omini and Eeco.

These springs are made by placing several flat strips one over the other. These are made of

steel plates. One flat strip is called a leaf. Lowest leaf is of smallest length and the length of

other leaves placed above this keeps on increasing progressively. In this way, the length of

top most leaf (main leaf) largest. Main leaf has eyes at the ends. All the leaves are clamped

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together at centre and sides by the centre bolt and side clamps respectively. The centre

portion of the leaf springs is connected to the axle with the help of U-bolt.

COIL SPRINGS

Coil springs are in the form of helix. These are made from special steel. It is made from steel

wire in the form of a coil. The coil springs absorb energy when this spring is compressed

while vehicle moves over road bump. The coil springs are mainly used in independent

suspension. However, these can also be used in the conventional rigid axle suspension. Coil

springs are capable of resisting shear and bending stresses but not torsion and side thrust.

When coil springs are used in the suspension system, other arrangements are made to bear

torsion and side thrust.

Advantages of Coil Springs

(a) Coil springs are better than leaf springs as they can absorb almost double energy per unit

volume as compared to leaf springs.

(b) They also require less space than leaf springs and can be used in very restricted spaces.

(c) Coil springs are lighter in weight for the same load.

(d) Compact in size.

Suspension Types -Dependent

Motion of a wheel on one side of the vehicle is dependent on the motion of its partner

on the other side

Rarely used in modern passenger cars

Can not give good ride

Cannot control high braking and accelerating torques

Used in commercial and off-highway vehicles

Hotchkiss Drive

•Axle is mounted on longitudinal leaf springs, which are compliant vertically and stiff

horizontally

•The springs are pin-connected to the chassis at one end and to a pivoted link at the other.

•This enables the change of length of the spring to be accommodated due to loading

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Fig 1 : Hotchkiss drive Fig 2 : Suspension in Maruti-Suzuki Omini

Suspension Types - Independent

•Motion of wheel pairs is independent, so that a disturbance at one wheel is not directly

transmitted to its partner

•Better ride and handling

Fig 3 : Macpherson Strut Fig 4 : Macpherson strut

Fig 5 : Trailing arm Fig 6 : Multi link

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STEERING SYSTEM

Introduction: This system provides the directional change in the movement of

an Automobile and maintain in a position as per the driver‟s decision without

much strain on him.

REQUIREMENTS OF STEERING SYSTEM:

a. It must keep the wheel at all times in to rolling motion with out

rubbing on the road.

b. This system should associate to control the speed.

c. It must light and stable.

d. It should also absorb the road shocks.

e. It must easily be operated with less maintenance.

f. It should have self-centering action to some extent.

Fig 7 : Rack and pinion steering system

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TRANSMISSION

Transmission is the mechanism which is used to transfer the power developed by engine to

the wheels of an automobile. The transmission system of an automobile includes clutch, gear

box, propeller shaft axle and wheels, etc. The term „Transmission‟ is used for a device which

is located between clutch and propeller shaft. It may be a gear box, an over drive or a torque

converter, etc.

CLUTCH

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.

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.

MAIN PARTS OF A CLUTCH

It consists of

(a) a driving member,

(b) a driven member, and

(c) an operating member.

Driving member has a flywheel which is mounted on the engine crankshaft. A disc is bolted

to flywheel which is known as pressure plate or driving disc.

The driven member is a disc called clutch plate. This plate can slide freely to and fro on the

clutch shaft.

The operating member consists of a pedal or lever which can be pressed to disengaged the

driving and driven plate.

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FUNCTION OF GEAR BOX

An automobile is able to provide varying speed and torque through its gear box. Various

functions of a gear box are listed below :

(a) To provide high torque at the time of starting, vehicle acceleration, climbing up a hill.

(b) To provide more than forward speeds by providing more than one gear ratios. In modern

cars, five forward gears and reverse gear is provided. For given engine speed, higher speed

can be obtained by running in higher (4th and 5th) gears.

(c) Gear box provides a reverse gear for driving the vehicle in reverse direction.

Fig 8 : Gearbox of Maruti-Suzuki Swift

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ANTI-LOCK BRAKING SYSTEM

Anti-lock braking system (ABS) is an automobile safety system that allows the wheels on

a motor vehicle to maintain tractive contact with the road surface according to driver inputs

while braking, preventing the wheels from locking up (ceasing rotation) and avoiding

uncontrolled skidding. It is an automated system that uses the principles of threshold

braking and cadence braking which were practiced by skillful drivers with previous

generation braking systems. It does this at a much faster rate and with better control than a

driver could manage. ABS generally offers improved vehicle control and decreases stopping distances on dry and

slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered

pavement, ABS can significantly increase braking distance, although still improving vehicle

control.

Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors,

and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors

the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the

others, a condition indicative of impending wheel lock, it actuates the valves to reduce

hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that

wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning

significantly faster than the others, brake hydraulic pressure to the wheel is increased so the

braking force is reapplied, slowing down the wheel. This process is repeated continuously

and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply

or release braking pressure 15 times per second. Because of this, the wheels of cars equipped

with ABS are practically impossible to lock even during panic braking in extreme conditions.

The ECU is programmed to disregard differences in wheel rotative speed below a critical

threshold, because when the car is turning, the two wheels towards the center of the curve

turn slower than the outer two. For this same reason, a differential is used in virtually all

roadgoing vehicles.

If a fault develops in any part of the ABS, a warning light will usually be illuminated on the

vehicle instrument panel, and the ABS will be disabled until the fault is rectified.

Modern ABS applies individual brake pressure to all four wheels through a control system of

hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on

most road vehicles produced today and is the foundation for electronic stability control

systems, which are rapidly increasing in popularity due to the vast reduction in price of

vehicle electronics over the years.

Modern electronic stability control systems are an evolution of the ABS concept. Here, a

minimum of two additional sensors are added to help the system work: these are a steering

wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple: when the

gyroscopic sensor detects that the direction taken by the car does not coincide with what the

steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s)

(up to three with the most sophisticated systems), so that the vehicle goes the way the driver

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intends. The steering wheel sensor also helps in the operation of Cornering Brake

Control (CBC), since this will tell the ABS that wheels on the inside of the curve should

brake more than wheels on the outside, and by how much.

ABS equipment may also be used to implement a traction control system (TCS) on

acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller

can detect the situation and take suitable action so that traction is regained. More

sophisticated versions of this can also control throttle levels and brakes simultaneously.

Upon the introduction of the Subaru Legacy in 1989, Subaru networked the four channel anti-

lock brake function with the all wheel drive system so that if the car detected any wheel

beginning to lock up, the variable assists the all wheel drive system installed on vehicles with

the automatic transmission would engage to ensure all wheels were actively gripping while

the anti-lock system was attempting to stop the car.

Fig 9 : Anti-lock Braking System Fig 10 : ABS of Maruti-Suzuki Swift

Speed sensors

The anti-lock braking system needs some way of knowing when a wheel is about to lock up.

The speed sensors, which are located at each wheel, or in some cases in the differential,

provide this information.

Valves

There is a valve in the brake line of each brake controlled by the ABS. On some systems, the

valve has three positions:

In position one, the valve is open; pressure from the master cylinder is passed right

through to the brake.

In position two, the valve blocks the line, isolating that brake from the master

cylinder. This prevents the pressure from rising further should the driver push the

brake pedal harder.

In position three, the valve releases some of the pressure from the brake.

Pump

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When the ABS system operates the brake lines lose pressure. The pump re-pressurizes the

system.

Controller

The controller is an ECU type unit in the car which receives information from each individual

wheel speed sensor, in turn if a wheel loses traction the signal is sent to the controller, the

controller will then limit the brakeforce (EBD) and activate the ABS modulator which

actuates the braking valves on and off.

REFERENCES

Sky Automobiles for pictues namely fig 2, fig 4, fig 8 and fig 10.

The Automobile Journal of India for information on ABS.

Wikipedia for other pictures.