An Insight Into Basic Auto Components and Their Functioning

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Akhilnandh Ramesh

AN INSIGHT INTO BASIC AUTO

COMPONENTS AND THEIR FUNCTIONING



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Booklet: version 1: 20th

march 2013

AUTHOR’S NOTE:

I have written this booklet so that a layman can understand the working ofwhat he sees commonly around him: an automobile. Any suggestions to

improve this booklet are always welcomed.

Please contact me through my email: [email protected] with

your feedback and suggestions.

I thank Sundaram Motors, Poonamalee for allowing me to visit them for in-

plant training and for their valuable insights into automotive components.

I thank Dr.Suresh Kumar, Professor, Department of Mechanical Engineering,

SSN College of Engineering, for guiding me to bring out such a booklet.

I thank Dr. V.E.Annamalai , Head of the Department, Department of

Mechanical Engineering, SSN College of Engineering for his encouragement

and support.

mailto:[email protected]






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CONTENTS:

TOPIC PAGE NO

INTERNAL COMBUSTION ENGINE 4

AUTOMOBILE TRANSMISSION AND GEARBOX 12

DIFFERENTIAL 20

STEERING SYSTEM 23

SUSPENSION SYSTEM 27

BRAKING SYSTEM 29

AUTO ELECTRICAL SYSTEMS OF A VEHICLE 35

REFERENCES USED 35



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INTERNAL COMBUSTION ENGINE:

An internal combustion engine is an engine in which the combustion of fluid

occurs inside the combustion chamber which is an integral part of an engine.

This is unlike an external combustion engine in which the combustion occurs in

a combustion chamber which is located outside the engine.

The first internal combustion engine was built by OTTO LENOIR in 1860.

A basic internal combustion engine may operate by 4 or 2 strokes:

WORKING OF A 4 STROKE INTERNAL COMBUSTION PETROL

ENGINE:

The 4 strokes which occur in an internal combustion engine are:

1. Intake stroke/suction stroke2. Compression stroke

3. Power stroke

4. Exhaust stroke

These strokes are repeated for every 2 revolutions of the engine.

1. Intake stroke/Suction stroke:

This is is the first stroke of the internal combustion engine. In this stroke, thepiston moves towards is lowermost position (Lower dead centre).The inlet

valve opens to allow enough air to enter the combustion chamber for

combustion. Fuel injectors spray fuel air mixture for combustion

2. Compression stroke:

In this stroke both the inlet valve and the outlet valve are closed. The piston

moves from the lower dead centre to the upper dead centre. Due to the



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upwards motion of the piston, the volume occupied by the fuel air mixture and

air decreases and hence compression occurs

3. Power stroke.

When the compression stroke is nearly complete, a spark plug produces a tiny

spark that ignites the fuel air mixture, causing combustion and thereby

producing power. The power produced due to the expansion of gases is

transmitted to the crankshaft. The piston is pushed to the lower dead centre

4. Exhaust stroke:

At the end of the power stroke, the exhaust stroke occurs. The piston starts

moving from the lower dead centre to the upper dead centre.The exhaust

valve opens and the exhaust gases are sent away from the combustion

chamber through it.

These 4 strokes occur continuously and might also overlap with each other.



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For the purpose of supplying the fuel, the fuel from the fuel tank is sent to the

fuel feed pump which in turn supplies it at great pressure to the fuel filter

which filters any dust particles. It then supplies it to the fuel injection pump.This pump supplies the fuel mixture to the carburettor at high pressure, for

mixing with air. The fuel is then sent to the fuel injectors which spray the fuel

on to the combustion chamber.

The spark produced by the spark plug and the rotation of the piston when an

engine is starting is brought about by auto electrical assembly

Working of the 4 stroke diesel engine is similar to that of the petrol engine.

However in the diesel engine, no spark plug is used and the fuel air mixture is

supplied along with the power stroke through fuel injectors. The combustion of

fuel occurs due to the high pressure occurring inside the combustion chamber

at the end of the compression stroke. The suction stroke is just used to suck in



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the air required to cause combustion .

THE PICTURE SHOWS THE 4 STROKES CYCLE OF AN INTERNAL

COMBUSTION ENGINE



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COMPONENTS AND CONSTRUCTION OF INTERNAL

COMBUSTION ENGINE ALONG WITH THEIR WORKING:

SECTION OF ICE WITH THE CYLINDER BLOCKS AND HEADS REMOVED.WHEEL AT

THE OTHER END OF THE CRANKSHAFT IS THE FLYWHEEL.

CYLINDER BLOCK:

An internal combustion engine consist a cylinder block. This is the basic

component of the an internal combustion engine.

These cylinder blocks consist of numerous cylinders into which the piston is

fitted.



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PISTON ALONG WITH CRANKSHAFTS:

A piston is part of an internal combustion engine which moves up and down

inside the cylinders of the cylinder block.

This motion of the piston is supported by the crankshafts. The crankshaft is a

long metal rod with appropriate grooves in it to which the pistons are fitted.

During the power stroke, when the power released causes the piston to move

downwards, the crankshaft too rotates. One end of the crank shaft is

connected to the flywheel while to the other end connecting rod is connected

FLYWHEEL:

Flywheel is connected to one end of the crank shaft. The flywheel is a rotating

mechanical device which is used to store and transfer rotating mechanical

energy to the components connected to it. The flywheel is connected to the

transmission input shaft which in turn connects the driveshaft.

CYLINDER HEAD AND CAMSHAFT:

Above the cylinder block, the cylinder head is mounted. The cylinder head

fastened on to the cylinder block by means of appropriate bolts.

The cylinder head is provided with valves which serve as inlet for air and outlet

for the exhaust gases. The cylinder head is also provided with appropriate

openings through which the fuel injectors and the spark plug(for petrol engine)

fit.



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The opening and closing of the valves at the end of the suction and exhaust

strokes is controlled by the camshaft. The camshaft draws power for opening

and closing of the valves by a belts or gears connected to the crankshaft. Thus

the rotation of the engine causes the camshaft to work.

INLET AND EXHAUST MANIFOLD:

The system of pipes in red and black are the inlet and exhaust manifolds

The inlet manifold is used to supply the inlet valves with fresh air.The inlet

manifold are connected to the inlet valve of the internal combustion engine.

The inlet manifold draws air from the atmosphere through the air intakes thatopen outside.

The exhaust manifold is used to remove the exhaust gases produced at the end

of the exhaust stroke.

OIL PUMP, SUMP AND LUBRICATION SYSTEM AND COOLING SYSTEM:

When the pistons, the crankshafts, the camshafts rotate, there is friction

between these parts which are in contact. This friction is minimized bylubrication using lubrication oil. The lubrication oil is stored in the oil sump

which is located below the cylinder block. The oil stored in the oil pump is

drawn by the oil pump which is driven by means of a belt or pulley connected

to the connecting rod at one end of the camshaft.

The oil drawn by the pumps is sent to fluid lines which supply the oil to the

rotating parts.



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The rotating motion of the engine components produces heat. The heat

produced by the rotating motion of the pistons and the crankshafts etc are

removed by means of cooling system using a coolant or water.

The coolant or water is stored in a coolant tank from which it is drawn bymeans of a water pump. The water pump is operated by the rotation of the

crankshaft by means of a pulley or a system of gears and is connected to the

connecting rod at one end of the crankshaft.

The water/coolant drawn is sent by water lines throughout the system and

acts as a heat exchanger taking away the engine heat.

ALTERNATOR:

An alternator is a generator which generates ac power. The purpose of

alternator in a vehicle is for charging the batteries which are used for running

the auto electricals and starting the engine after it has stopped.

The alternator gets drive from the connecting rod of the crankshaft which

rotates along with the crankshaft. The drive is provided by means of a

belt/pulley set up or a system of gears.

TURBOCHARGER SYSTEM WITH INTERCOOLER:

The turbocharger system is a method of forced induction by which the

performance of the engine can be improved. The turbocharger is uses exhaust

gases to drive a turbine for drawing more air for better combustion of fuel air

mixture in the combustion chamber thereby ensuring less polluting exhaust

gases.

This air drawn by the turbine is hotter and is less in oxygen content. Therefore

it is passes through an intercooler before being supplied to the inlet valve

which is a heat exchanger for cooling the air and enriching the oxygen content.

The turbocharger ‘s intake system is connected to the exhaust manifold.



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TURBO CHARGER

AIR COMPRESSOR:

Air compressor is an air pump which is used for running the air conditioning

system of a car and also the air brakes and air suspension systems seen in

heavy vehicles. The air compressor again takes drive from the connecting rod

of the crankshaft connected by means of pulley/belt or gears. Depending on

the requirements, many air compressors may be required.

AUTOMOBILE TRANSMISSION SYSTEM AND GEARBOX

An automobile’s transmission system is used to transmit power from the

engine to the axles which are used to drive the wheels. A transmission system

is used to control and regulate the power supplied by the engine to the speed.The transmission system of an automobile consists of numerous speed and

torque regulating gears, the drive shaft and the clutch and the differential.

NEED FOR TRANSMISSION SYSTEM:

The power output of an internal combustion engine is not suitable for

driving the wheels as it is at a higher rpm. The transmission system

adapts the output and makes it suitable for rotating the wheels by

reducing the speed



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The gears connected to the transmission systems are used to control

speed of rotation of the wheels

The different gears of different sizes regulate the torque applied to the

wheels for rotating.

MANUAL TRANSMISSION

Manual transmission system is the most commonly used transmission system

in India. Most of the cars and commercial vehicles sold here come fitted with

manual transmission.

Universally all the manual transmission systems used today have been

designed as synchronized transmission systems.

However non synchronous transmission systems do exist and find application

in heavy vehicles.

COMPONENTS AND WORKING OF THE MANUAL

TRANSMISSION

A basic transmission system consist of a set of gears, a clutch and drive shafts

which are connected to the differentials located on the driven wheel axles. The

following are the components of the transmission system:

CLUTCH:

A Clutch consists of a clutch plate fitted over the flywheel of the engine.



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A pressure plate is fitted over the clutch plate by means of struts and

bolts.

The pressure plate is connected to diaphragm springs.

These are connected to a clutch housing provided with a fork for

engaging the clutch pedal.

A transmission input shaft connects the clutch and the transmission

system. The fork for engaging the clutch pedal is connected to this drive

shaft. The fork is connected to the clutch pedal by means of a cable.

However in certain cases, for effective pressing of the clutch, one may

also use hydraulic or air mechanisms.

The clutch is said to be in engaged position when the clutch pedal is not

pressed.In this condition, the springs push the pressure plate on the clutch plate

causing the clutch to push against the flywheel. This causes the

transmission input shaft to rotate along with the flywheel in the same

speed.

When the clutch is pressed, the clutch is said to be in disengaged

condition.

In this condition the diaphragm of the clutch is pressed and this in turn

causes a series of pins to pull the springs which are pushing against the

pressure plate away from it. As a result the clutch is not pressed on the

flywheel anymore hence the transmission input shaft/lay shaft does not

rotate with the same speed

When this happens, the transmission output shaft too does not rotate in

the same speed and momentarily slows down. This allows for shifting of

gears. When the clutch

pedal is released theclutch moves to engaged

condition again and the

transmission input shaft

continues to rotate with

the same speed as the

flywheel’s speed.



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An automobile clutch showing the springs (fitted over the pressure

plate) and clutch plate

GEARBOX:

Picture in the previous page shows the gearbox ( with layshaft below

and the driveshaft above).The dog clutches connected to the gear

shifting forks can be clearly seen.

The gear box consist of 2 shafts:

The transmission input shaft which gets the input for rotation

from the flywheel and is connected to the clutch. This shaft has a

series of gears of various sizes.

The drive shaft which is connected to the differentials connected

to the driven wheels. This shaft to has a series of gears of various

sizes. The gears are numbered in increasing order from 1.The size

of the gears decreases as we progressively move from one gear toanother. Hence the speed of rotation of the gears progressively

increases and torque supplied by the gears decreases. Mechanism

for shifting between the gears is provided here.

When a gear is selected, depending on the type of gearboxes, contact

between the both the gears and the drive shaft is established and this

causes the drive shaft to rotate with a particular speed and torque.



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The speed of rotation of the drive shaft and the torque supplied to it

is determined by the size of the gear.

The shaft is connected to the differential which is fitted to the axles

driving the driven wheels.

The working of the differential is explained in the next segment

NON SYNCHRONOUS AND SYNCHRONOUS GEARBOXES:

First type of gearbox that was developed is the sliding mesh gearbox.

In this type of system, the gears are engaged by bringing sliding the

gears on to the shaft. The gears are engaged only when the speed of the

gears rotating in the lay shaft and the speed of the corresponding gearsrotating in the main shaft match.

Thus the gears mesh and gears are engaged. To ensure this , a driver of a

vehicle fitted with such a gearbox needs to control the throttle with

careful timing and reduce the speed of the engine.

This can be done by engaging the neutral gear for a moment so that the

engine speed is lowered and again engaging the required gear with

proper timing, making such vehicles difficult to control.

To overcome this, constant mesh transmission systems were developed where

the gears mesh at all times and are always rotating. This action is brought

about by means of a dog clutch which is splined on to the drive shaft and slides

into corresponding dog teeths in the drive shaft of the vehicle and rotates

along with the gears.

However if the dog clutch and the dog teeth are not rotating in the same

speed, the gears may not be engaged properly and this may result in

production of grinding noise. Further this also may wear out the dog clutches.

This necessitates the need for careful throttle control and in some cases

bringing the transmission to neutral before engaging the gear



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Sliding mesh transmission system

The gears in the input shaft and the gears in the drive shaft (output shaft)

mesh at all times. Gear action is brought about by the dog clutches which are

engaged by the shift forks connected to gear selector.



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Dog clutches and Dog teeths(on gear)

This problem is overcome by synchromesh gearboxes in which the dog clutch

has a synchronizer mechanism which consist of synchrocones and

synchrorings.

Before the dog clutch engages, the synchrocone engages first, bringing thespeed of both the dog clutches and gears to match by developing friction

between the two.

The synchrorings prevent the dog clutch from making contact with the gear till

the speeds match (synchronization).

When the synchronization occurs, friction on the synchrorings is relieved and

these twist slightly, causing dog clutch to make contact with the gear.

Thus by means of synchrocones and synchrorings,the noise produced when

the transmissions do not engage properly are removed and the need for the

driver of the vehicle to control the throttle with timing is too removed.



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SYNCHRO RINGS

SYNCHRO MESH GEARS

WORKING OF THE REVERSE GEAR

The reverse gear consists of an intermediate gear provided between the

corresponding gear in the lay shaft and the corresponding gear in thedriveshaft.

Generally, when 2 gears rotate, it is seen that the each gear rotates in a

sense opposite to the other.

The general sense of motion of an engine’s flywheel is in clockwise

direction. However since for forward motion the wheels rotate in

anticlockwise direction, the gears ensure that this is achieved.

Now for motion in reverse direction the wheels rotate in clockwise

sense. This is achieved by providing an intermediate gear which rotates



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in the opposite sense with respect to that of the lay shaft between the

gear in the lay shaft and the drive shaft.

This ensures that the gear in the drive shaft rotates in the same sense of

direction as that of the lay shaft, ie clockwise sense.

Hence the wheels rotate in clockwise sense and reverse motion is

achieved.

In certain cases,the first gear and the reverse gear of a synchromesh gearbox

may not be provided with the synchro cones and rings as these gears are

operated only after the vehicle has come to a stop or is moving slowly.

DIFFERENTIAL

A differential is a device which, in automobiles is used to regulate and control

the speed of one of the wheels connected to the propeller shaft with respect

to another. Working of a differential is seen when a vehicle is executing a turn.

When a vehicle makes a turn,say towards the right, then it is seen that the

wheel on the left hand side needs to cover a larger distance and travel faster

when compared to the wheel on the right hand side. In automobiles which do

not posses a differential, it is seen that irrespective of whether the vehicle is

moving straight or executing a turn, both the wheels rotate at the same speed

always. This makes controlling the vehicle very difficult when its turning.

However it is seen that using a combination of gears which regulate the speed

of motion of one wheel with respect to another, can be controlled and hence a

turn can be executed easily

BASIC COMPONENTS AND WORKING OF THE

DIFFERENTIAL

A differential consist of the following:

1. Crown gear which receives the torque by means of an input pinion from

the drive shaft

2 Planet gears connected to the crown gear which can rotate as well as spin as

well as rotate about it’s axis. Input torque is applied to the ring gear (here in



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blue), by means of an input pinion (not shown here) connected to the

driveshaft (Refer Figure 1 )

This turns the entire carrier (also in blue). The carrier is connected to the 2 sun

gears (red and yellow) only through the planet gear (green).

Torque is transmitted to the sun gears through the planet gear. The planet

gear revolves around the axis of the carrier, driving the sun gears.

If the resistance at both wheels is equal, the planet gear revolves without

spinning about its own axis, and both wheels turn at the same rate.

If the left sun gear (red) encounters resistance, the planet gear (green) spins as

well as revolving, allowing the left sun gear to slow down, with an equalspeeding up of the right sun gear (yellow).(Refer Figure 2)

Now the resistance is recognized by means of change in orientation of the 2

(or 1) planet gears/ planet gear .These are mounted on an axis perpendicular

to the axis on which the sun gears are located. The resistance,ie measure of

change in direction is recognized by means of change in the orientation of the

planet gears which in turn is recognized by means of change in the orientation

of crown gear connected to the propeller shaft

A differential does not reduce or lower the torque supplied to it. Rather it

distributes the torque linearly between the two wheels which it operates thus

regulating the wheel’s angular velocity and hence the vehicle’s speed.

Differential regulates the torque according to the equation

aA=bB+Cc

Where A=angular velocity of the propeller shaft,B and C=angular velocity of the

half axles connected to the wheel. a,b,c being constants.

3.A pair of sun gears, each connected to the axle half shaft connected the

wheels which are used for speeding or slowing down the wheels



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A cut away section of differential showing the crown wheel(big wheel towards

the left),2 planet gears,1 sun gear(the other hidden by the crown wheel, the

axle half shafts which connect to the wheels and the differential carrier.

Working of the differential when both the sun gears do not encounter

resistance and the vehicle is moving in a straight line(FIGURE 1).



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Working of the differential working when left sun gear encounters resistance

when vehicle moves towards left-previous page (FIGURE 2).

STEERING SYSTEM

A steering system consists of a set of devices and components which allow a

vehicle to follow a desired course.

The basic aim of the steering is to ensure that the wheels point towards the

right direction. This is achieved by many links and arms provided inside the

steering system.

The most common type of steering systems in use today are the

Rack and Pinion Steering system

The recirculating ball type steering system

In addition to this, each steering can be power assisted, where the effort done

by the human beings in turning the steering is reduced by means of hydraulics

or electronics.

THE RACK AND PINION STEERING SYSTEM

It is the most common type of steering system. It finds a lot of use in cars and

small trucks.

It has a rack and pinion gear set kept inside a metallic tube. Each end of the

rack protrudes from the metallic tube and a tie rod connects this set up to the

steering arm connected to the wheel.

When the steering column is turned, the gear spins, moving on the rack. this

cause the linear motion of the tie arm in turn connected to the steering arm

which moves the wheels.

The rack and pinion steering system does the following things:

It converts the rotational motion of the steering wheel into linear

motion which is required to turn the wheels

It makes it easier for turning the wheels by producing a gear reduction



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RECIRCULATING BALL TYPE STEERING SYSTEM

This type of steering system is mainly used in trucks and other commercial

vehicles.

This type of steering system consist of a worm gear, ie a metal block with

threaded hole inside it and gears cut on to the outer portion of it.

To this, a corresponding gear is fitted. This gear is used to move the pitman

arm which is connected to the steering rod. The motion of the pitman arm



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causes the linear motion of the track rod which in turn causes the linear

motion of the tie rod which is required to turn the wheels.

Now the steering column coming from the gearbox has a set of grooves which

fit into the threads present inside the metal block. Instead of twistingcompletely and moving all the way down the worm gear, the steering column

with threads is held fixed so that it moves only the gears used to move the

pitman arm.

Now instead of making the steering column directly engage the grooves

present in the worm gear, a system of recirculating ball bearings is provided

these recirculate through the grooves present in the steering arm as they turn.

These balls reduce friction between the grooves thus reducing wear and tear

of contact for a moment,making the steering feel very light and loose.

HYDRAULIC POWER STEERING

(Picture of Rack and pinion power steering)



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The power assisted rack and pinion system reduces the effort done by the

driver of the vehicle in turning the steering wheel and in turn causing the

wheel to turn.

This system makes use of hydraulic fluids to turn the steering column inaddition to the mechanical effort done by the driver thereby reducing driver

effort.

In addition to the basic components of a rack and pinion type and recirculating

ball type steering, a hydraulic power steering has the following:

PUMP

The pump consist of rotary vanes. These are rotated by the engine andare connected to the engine’s connecting rod by means of a pulley and a

belt or by means of gears.

These draw fluid from a fluid reservoir at a lower pressure and supply it

to the fluid lines that are connected to the steering system at a high

pressure.

The amount of flow of the fluid supplied depends on how fast the pump

rotates (determined by the engine’s speed).The pump also contains a

pressure valve that is used for regulating the fluid pressure at high

speeds.

ROTARY VALVE

The rotary valve is a valve which is used to sense the direction of

rotation of the steering wheel .This is used because the power steering

system must assist only when the steering column rotates and not when

the car is moving in a straight line.The rotary valve has a torsion bar, a piece of metal which twists when

torque is applied to it. The top of the bar is connected to the steering

column and the bottom of the bar is connected to the pinion or the

worm gears. The torsion valve is located inside the spool valve assembly

which has ports which open to the fluid lines.

As the torsion bar rotates, it also rotates the spool valve assembly.

Depending upon the direction of rotation, extra ports supplying



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hydraulic fluids open resulting in supplying of more hydraulic fluid in one

direction with respect to the other.

When the steering wheel is not turned, the fluid valves supply a constant

amount of hydraulic fluid. When the wheel is turned towards a

particular direction, more fluid is supplied on that direction when

compared to other side thereby causing the steering column to turn

easier.

SUSPENSION SYSTEMSSuspension is the term given to the system of shock absorbers, linkages

and springs which establishes a contact between the vehicle’s body and

the wheels and allows relative motion between the two.

Suspension systems serve a dual purpose —contributing to the

vehicle's handling and braking for good active safety and driving

pleasure,

Keeping vehicle occupants comfortable and reasonably well

isolated from road noise, bumps, and vibrations etc.

There are several types of suspension systems and their use depends

on the type of application and the type of load which the vehicle carries.

Commercial vehicles and buses of today use air suspension systems

which makes use of compressed air

Semi elliptical leaf spring suspension: most common in commercial vehicles:



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AIR SUSPENSION

An air suspension consists of balloons/bags made of plastics and rubber into

air is fed at right pressure.

An air compressor is used to feed the air into these plastic balloon setups.

These air compressor maybe powered by a vehicle’s on board electrical or by

an air pump connected to the engine.

Valves are provided at appropriate positions for controlling the air pressure

and in modern vehicles ,the system maybe electronically controlled where a

driver can choose several suspension set ups by changing the amount of air in

the plastic balloons.

When a vehicle moves over a rough road,the pressure of air in each plastic

balloon is coordinated so that the occupant of the vehicles get a smooth ride

and the ride height is maintained.



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BRAKING SYSTEM

Braking system of a vehicle is used to inhibit the motion of wheels of the

vehicle. Most common brakes of a vehicle is used to convert the kinetic energy

of motion of the vehicle into heat by means of friction.

TYPES OF BRAKES:

Brakes can be classified into:

FRICTIONAL BRAKES: Frictional brakes use friction to retard the rotating

motion of the wheels by converting it into friction. These type of brakes make

use of brake pads and brake shoes which can grip on to the wheels of vehiclescausind slowing down.

PUMPING BRAKES: These are used wherever a pump is used.For example, if

the piston of an ICE Engine has it’s fuel supply cut, Then the internal pumping

losses can cause braking. The change in energy which occurs when the fuel

supply is cut can be used to retard the motion

ELECTROMAGNETIC BRAKES: These are used in most cases whereelectrical motors are in place. In these, the motion of a rotating component is

hindered by means of introducing eddy currents in the rotating components by

using powerful electromagnets and thus stopping the vehicles. This type of

system is used in electric trains and engines.



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BASIC COMPONENTS AND WORKING OF A HYDRAULIC BRAKE

SYSTEM:

A brake that makes use of the principle of hydraulics and hydraulic fluids to

cause braking action is called a hydraulic brake system.

A hydraulic brake system is better than mechanical braking systems since by

transferring force via incompressible fluids, losses due to friction etc are

minimized and a greater force is available to be exerted on the brake pads.

Further, by means of using piston cylinders of appropriate sizes, the forceapplied when the brake pedal is pressed can be multiplied. On the other hand

when mechanical braking systems are used, there may be loss in the force

exerted as it gets transmitted over mechanical cables.

When the brake pedal is pressed, a force is applied on a rod supported by the

lever. The lever system ensures that the force applied by the leg is multiplied

many times before pushing the brake. This is done by the principle of moments

in mechanics. The end of the lever located near the point of application of



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force is longer than the end of the lever located on the side away from the

support on which the lever is mounted.

This ensures that a greater force is available to push the piston in the master

cylinder.

The master cylinder consists of a piston or a collection of pistons.

Often many pistons are operated in tandem. Such a master cylinder system is

called tandem master cylinder.

The hydraulic fluid fills the fluid lines from the wheels, upto the master

cylinder.

When the piston is pressed, the hydraulic brake fluids being nearly

incompressible transmit the force on to the wheel cylinders mounted on to the

each wheel. Further by adjusting the cross sectional area of the fluid lines,force

is also multiplied.

The wheel cylinder consists of 2 pistons which in turn are connected to the

brake shoe/pads on the wheels.

The pistons, due to the force transmitted by the hydraulic fluids, move awayfrom each other and hence exert a force on the 2 brake shoes/pads causing

them to grip on to drums/discs present in the wheels the wheels.

These brake shoes/pads convert the kinetic energy of the rotating wheel into

heat energy by friction thus hindering motion.

The brake shoes/pads can be made to grip against a rotating drum or a

rotating disc.

Generally rotating discs are preferred over rotating drums as a disc can cool

more easily compared to a drum. Also a rotating discs are easier to disengage

compared to a rotating drum.

Heat produced during the process of braking might cause the diameter of the

drum to increase, resulting in the shoes/pads having to move further to apply

the force. Further heat produced may also cause changes in frictional property

of the material lowering the friction and may also cause the hydraulic brakefluid to vaporize. Hence rotating discs are preferred over a drum



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this picture shows a disc brake in a motorcycle along with brake

shoes

This picture shows drum brakes in a wheel of a motorcycle along

with brake shoes



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BASIC COMPONENTS AND WORKING OF AN AIR BRAKE:

Most of the commercial vehicles of today use air brakes which make use of

compressed for braking action.

Air compressor: An air compressor is used to pump in the air into the

storage tank for use in the braking system. The air compressor may be

driven by an electric motor or by drive taken from the engine’s rotating

shaft.

Air compressor governor/pressure controller: It is used to keepthe pressure of air supplied below a the safety limit of the air reservoir.It

is provided with a safety valve for release of excess air.

Air reservoir: Holds the compressed air for use in the braking system.

Drain valves: Used to drain the air from the reservoir when vehicle is

stationary

Brake Pedal: It is used to supply air from the reservoir

Pushrod: It is similar to a piston. When it is depressed ,brakes are

released and vice versa.

Slack Adjuster: It is an arm which is used to connect the push rod of

the brake and the s cam of the brake which pushes the shoes against the

brake drums.

S cam: An s cam is an s shaped diaphragm that pushes against the brake

shoe when brake is engaged. Brake shoe: It is used to exert frictional force against the rotating drum

of the wheels

Return springs: These are used to disengage the brake shoes when not

pressed.



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When the brake pedal is not in use, and then the air brake system is filled with

air, the diaphragm is in closed position and does not press the brake shoe.

When the brake pedal is pressed, the pressure decreases and the diaphragm

presses against the brake shoe.

When the pedals are released, the air pressure is comes back to the original

state and the air compressor pumps in more air to make up for the loss.

Emergency brakes in trucks complement the air brake. While starting the

vehicle, the emergency brake has to be released to fill the system with air.

When the emergency brake system is filled with air, there is no braking

however when there s a leak in the system, emergency brakes engage and the

vehicle comes to a stop.

Parking brakes of a vehicle are generally cable operated and cause the brake

shoes to grip against the disc/drum when the vehicle is stationary to prevent

any motion which may occur when a vehicle is stationary.



AUTOELECTRICAL SYSTEMS OF A VEHICLE:

Auto electrical systems of a vehicle consist of a battery which is recharged by

an alternator attached with the engine.

The battery is used is generally produces 12v while in trucks and buses,2

batteries may be connected in parallel to get an output of 24v.

The batteries are used to provide power to a circuits which are used for

powering the headlamps and cabin lamps etc.

The batteries are also used in ignition circuits.

Ignition circuit gets completed when the ignition is turned on during vehicle

start.The ignition coil is used to step up the voltage of 12v or 24v into 1000s of

volts required for producing a spark.

Further the flywheel and the cranks of the engine are also rotated by means of

solenoid coils due of magnetic fields in them or by means of electrical motors

which cause cranks to rotate.

REFERENCES USED:

Notes taken during practical training at Sundaram Motors,Poonamalee.

www.wikipedia.org

www.google.com- images

http://www.wikipedia.org/


http://www.google.com-/




Date post:	04-Jun-2018
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An Insight Into Basic Auto Components and Their Functioning

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