The document is a vocational training report submitted by Praveen Kumar Kushwaha to fulfill the requirements for a Bachelor of Technology degree in Mechanical Engineering. The report details Praveen's training at Megha (Chevrolet) Auto Workshop in Lucknow, India. It includes sections on the history of Chevrolet, vehicle systems like chassis, suspension, steering, brakes, and engines, as well as acknowledgements and contents pages.

1. A VOCATIONAL TRAINING REPORT ON
“MEGHA (CHEVROLATE) AUTO WORKSHOP,
LUCKNOW”
Submitted in partial fulfillment of the requirements
For the award of the degree
BACHELOR OF TECHNOLOGY
IN
MECHANICAL ENGINEERING
SUBMITTED BY
PRAVEEN KUMAR KUSHWAHA
(ROLL NO. – 1443140057, Final Year)
DEPARTMENT OF MECHANICAL ENGINEERING
B.N.COLLEGE OF ENGINEERING AND TECHNOLOGY
AFFILIATED TO
A.P.J.ABDUL KALAM TECHNICAL UNIVERSITY

2. Acknowledgement
Every project big or small is successful largely due to the effort of a number of
wonderful people who have always given their valuable advice or lent a helping
hand. I sincerely appreciate the inspiration; support and guidance of all those
people who have been instrumental in making this project a success.
I, Praveen Kumar Kushwaha student of B.N. College of Engineering &
Technology Mechanical Engineering), am extremely grateful to “Megha
(Chevrolet) Auto Workshop” for the confidence bestowed in me & entrusting
my project.
At this juncture I feel deeply honoured in expressing my sincere thanks to Mr.
Naveen Agnihotri, Manager (Chevrolet Megha Auto Workshop) for making the
resources available at the right time & providing valuable insights leading to
the successful completion of my project.
I express my gratitude to Mr. Abhay P.S. Chauhan patiently teaching me and
guided me through the entire project.
Last but not the least, I place a deep sense of gratitude to my fellow trainees
who gave me insights into the working of all the departments in the plant and
therefore helped me better understand the ways of the company.
Praveen Kumar Kushwaha

3. CERTIFICATE
It is being certified that this training report has been submitted by Praveen
Kumar Kushwaha, bearing roll no- 1443140057 (Final Year, ME) is original &
all the work has been done by student himself.
He is permitted to submit the report for partial fulfillment of the award of
degree.
SIGNATURE OF THE EVALUATOR
SIGNATURE OF THE TRAINING INCHARGE
SIGNATURE OF HEAD OF DEPARTMENT
DATE OF SUBMISSION:

4. CONTENTS
 History of Chevrolet
 Chassis and suspension System
 Steering System
 Wheel Alignment
 Brakes(Disc & Drum)
 Tyre Notations
 Tools
 Clutch & Flywheels
 Engine Dismantling
 Differential
 Lubrication System
 Gear Box
 Ignition System
 Fuel Supply System
 Valve Mechanism
 Compression Ratio
 Engine Assembly
 Electrical System
 Air Condition
 Mileage
 Piston
 Crank
 Connecting Rod
 Bearings
 Antilock Braking System(ABS)
 Air Bags
 New Technologies Introduced

5. History of Chevrolet
Founded in 1911, the Chevrolet brand is the top selling marque within the General Motors
family and is the best-known GM nameplate. Chevrolet is virtually synonymous with
General Motors.
Chevrolet was co-founded by Louis Chevrolet and William C. Durant, the former a race
car driver, and the latter the founder of General Motors. Prior to creating General Motors,
Durant was head of Buick and in that capacity hired Louis Chevrolet to drive his cars in
motor races to promote the brand.
Durant’s tenure as the founder of GM was short lived and he found himself forced out of
the company in 1910. Keen to re-establish his credibility in Detroit and in the fledgling US
motor industry, Durant formed an alliance with Louis Chevrolet to found the company that
would make use of Chevrolet’s designs for a new range of vehicles in 1911.
Two years later the famous Chevrolet “bowtie” was adopted as the company logo. Two
theories exist as to the origins of the logo. One favours the story that it was an adaptation
of a pattern featured on wallpaper seen by Durant in a French hotel, while the other
suggests that the logo was a stylized adaptation of the cross on the Swiss national flag,
paying homage to Louis Chevrolet’s Swiss nationality.
General Motors, one of the world’s largest automakers, traces its roots back to 1908.
With its global headquarters in Detroit, GM employs 205,000 people in every major
region of the world and does business in some 157 countries. GM and its strategic
partners produce cars and trucks in 31 countries, and sell and service these vehicles
through the following brands: Buick, Cadillac, Chevrolet, FAW, GMC, Daewoo, Holden,
Jiefang, Opel, Vauxhall and Wuling. GM’s largest national market is the United States,
followed by China, Brazil, Germany, the United Kingdom, Canada, and Italy. GM’s
OnStar subsidiary is the industry leader in vehicle safety, security and information
services. General Motors acquired operations from General Motors Corporation on July
10, 2009.

6. Chassis & Suspension System
CHASSIS: Chassis is a skeletal frame on which various mechanical parts like engine,
tires, axle assemblies, brakes, steering etc. are bolted.
It is the most crucial element that gives strength and stability to the vehicle under
different conditions.
FRAME: A vehicle frame is the main supporting structure of the chassis of a motor
vehicle. All other components fasten to it.
Automobile frames provide strength and flexibility to the automobile.
BODY: Body provides supports in a vehicle.
Types of Chassis
Chassis is the base of a vehicle. It consist engine, transmission system, brake system,
suspension system, steering system, cooling system, wheels etc.
There are two types of chassis:
1. Conventional chassis or frame-full chassis
In this type of chassis the body is made as a separate unit and then joined with ladder
frame. It supports all the systems in a vehicle such as the Engine, Transmission system,
Steering system, Suspension system.
Advantage:

7. • Higher load capacity and strength
Disadvantage:
• The body tends to vibrate easily and the overall vehicle handling and
refinement is lower.
It is used in truck, bus and in SUV cars and bigger vehicles.

8. 2. Non conventional or frameless chassis
In this type of chassis the ladder frame is absent and the body itself acts as the
frame. It supports all the systems in a vehicle such as the Engine, Transmission
system, Steering system, Suspension system.
Advantages:
• Less rattles and squeaks are developed.
• Handling is better due to the higher body rigidity and weight.
Disadvantages:
• The load carrying capacity is lower.
• It is not safe in accidental condition.
Used mostly in hatchback and sedan cars.

9. Suspension System
 Suspension is the system of tires, tire air, springs, shock absorbers and
linkages that connects a vehicle to its wheels and allows relative motion
between the two.
 Suspension systems serve a dual purpose — contributing to the vehicle's
road holding/handling and braking for good active safety and driving
pleasure, and keeping vehicle occupants comfortable and a ride quality
reasonably well isolated from road noise, bumps, vibrations etc.
 There are three types of suspension systems:-
 Independent Suspension system
 Dependent Suspension System
 Semi-Independent Suspension System
Leaf spring and MacPherson strut:
A typical suspension system on a rear-wheel-drive car. It has a live rear axle on leaf
springs, and independent front suspension of the MacPherson-strut type with interior
damper.

10.  Independent suspension:
 Wishbone suspension:
A double-wishbone suspension. Wishbones are fitted at their outer ends to the top and
bottom of the steering swivel member. The two forks of each wishbone extend inward
to pivot on the frame. A tie rod - a steadying bar - is connected between the frame and
the lower wishbone.
 Instead of sharing a common axle, each wheel on a car with independent
suspension is independently attached to the body. Different spring combinations
may be used.
 When driven wheels are independently suspended, the differential is fixed to
the frame and drives the wheels by jointed drive shafts.
 There are five types of suspension system in common use.
 Double wishbones are used mostly at the front. There are two wishbones, one above
the other, to keep the wheel upright as it rises and falls.

11.  MacPherson-strut suspension can be used at both front and rear. The wheel hub is
fixed rigidly to an upright, telescopic, tubular strut which has its top end anchored to
the frame or to a reinforced wing.
 On front wheels, the whole strut swivels to allow steering. Pivoted arms extend
inward and forward to the frame in order to keep the wheel upright and resist
accelerating and braking forces.
 A trailing arm is attached to the wheel hub at one end, and extends forward to a
pivot on the frame.

 The arm may be broadened into a V shape with two pivots, either side by side or
with the inner pivot slightly behind the front one - a semi-trailing arm. Trailing arms
are usually found at the rear only.
 Trailing-arm suspension:
 A trailing-arm suspension on a rear-wheel-drive car. The arm is attached to the rear
wheel hub and broadens into a V whose two arms extend forward to pivot on the
frame. The differential is fixed to the frame and the drive shafts have universal
joints.

12.  A leading arm, used only at the front, is the opposite of a trailing arm, with the
wheel in front of the pivot.
 Swing axles may be at the front or rear. The system is like a beam axle cut in half
and attached to pivots on the frame.
 Usually the half-axle is broadened into a V with front and rear pivots to keep it from
twisting.
 Anti-roll bar:
 Pivots allow the bar to twist, but to a limited degree so that rolling is controlled.
 To restrain cars from rolling - leaning over on corners - an anti-roll bar is used, often
at the front, sometimes at the back and sometimes at both front and back.
 When one wheel moves up it pulls up one end of the bar and the other end pulls up
the other wheel, keeping the car level.
 Limited roll is allowed by the twisting of the bar.
 Non-independent suspension:
 A rear-wheel-drive car often has a live axle, a tube containing both the
drive shafts (half shafts) and the differential gears. A four-wheel-drive car
may have a live front axle as well.
 A dead axle - a rigid beam - is now used at the front on vans and trucks
only. Some front-wheel-drive cars have a dead rear axle.
 A rigid axle will have springs and links to prevent sideways movement.

13. Steering System
 Steering is the term applied to the collection of components, linkages, etc.
which will allow a vehicle to follow the desired course.
 An automobile is steered with the help of steering gears and linkages
which transfer the motion of the hand operated steering wheel to the
pivoted front wheel hubs via steering column.
 The other parts that are used for steering a vehicle are steering wheel
pads, steering shafts, steering box, steering arm & steering stabilizers.
 The steering effort passes to the wheels through a system of pivoted
joints. These are designed to allow the wheels to move up and down with
the suspension without changing the steering angle.
 They also ensure that when cornering, the inner front wheel - which has to
travel round a tighter curve than the outer one - becomes more sharply
angled.

14.  The joints must be adjusted very precisely, and even a little looseness in
them makes the steering dangerously sloppy and inaccurate.
 There are two steering systems in common use - the rack and pinion and
the steering box.
 On large cars, either system may be power assisted to reduce further the
effort needed to move it, especially when the car is moving slowly.
The rack-and-pinion system:
Rack-and-pinion gear
The pinion is closely meshed with the rack, so that there is no backlash in the gears. This gives very
precise steering.
At the base of the steering column there is a small pinion (gear wheel) inside
housing. Its teeth mesh with a straight row of teeth on a rack - a long
transverse bar.
Turning the pinion makes the rack move from side to side. The ends of the
rack are coupled to the road wheels by track rods.
This system is simple, with few moving parts to become worn or displaced, so
its action is precise.
A universal joint in the steering column allows it to connect with the rack
without angling the steering wheel awkwardly sideways.

15. The steering-box system:
At the base of the steering column there is a worm gear inside a box. A worm
is a threaded cylinder like a short bolt. Imagine turning a bolt which holding a
nut on it; the nut would move along the bolt. In the same way, turning the
worm moves anything fitted into its thread.

16. Wheel Alignment
Alignment refers to an adjustment of a vehicle’s suspension – the system that connects a
vehicle to its wheels. It is not an adjustment of the tires or wheels themselves. The key to

17. proper alignment is adjusting the angles of the tires which affect how they make contact
with the road.
CAMBER, TOE, & CASTER:
When a technician checks your tire alignment, he or she is mainly concerned with three
things:
1. CAMBER:
This is the inward or outward angle of the tire when viewed from the front of the vehicle.
Too much inward or outward tilt, also known as negative and positive camber,
respectively, indicates improper alignment and will need to be adjusted. Worn bearings,
ball joints, and other wheel-suspension parts may contribute to camber misalignment.
2. TOE:
Distinct from camber alignment, toe alignment is the extent to which your tires turn inward
or outward when viewed from above. If that’s confusing, just stand up and look down at
your feet. Angle them inward toward the center of your body. When the tires on your car

18. are angled the same way (remember, we’re thinking in terms of birds-eye-view), we call
this toe-in alignment. Angle your feet outward and you have toe-out alignment. Both
require adjustment.
3. CASTER:
Your caster angle helps balance steering, stability, and cornering. Specifically, it’s the
angle of your steering axis when viewed from the side of your vehicle. If you have positive
caster, the steering axis will tilt toward the driver. Negative caster, on the other hand,
means the steering axis tilts toward the front of your vehicle.
Power-assisted steering

19.  On a heavy car, either the steering is heavy or it is inconveniently low geared - the
steering wheel requiring many turns from lock to lock.
 Heavy gearing can be troublesome when parking in confined spaces. Power-assisted
steering overcomes the problem. The engine drives a pump that supplies oil under
high pressure to the rack or the steering box.
 Valves in the steering rack or box open whenever the driver turns the wheel,
allowing oil into the cylinder. The oil works a piston that helps to push the steering
in the appropriate direction.
 As soon as the driver stops turning the wheel, the valve shuts and the pushing action
of the piston stops.
 The power only assists the steering - the steering wheel is still linked to the road
wheels in the usual way.
 So if the power fails, the driver can still steer but the steering becomes much
heavier.
Brakes (Disc & Drum)

20.  An automotive braking system is a group of mechanical, electronic and hydraulically
activated components which use friction / heat to stop a moving vehicle.
Disc brake:
 A disc brake has a disc that turns with the wheel. The disc is straddled by a caliper,
in which there are small hydraulic pistons worked by pressure from the master
cylinder.
 The pistons press on friction pads that clamp against the disc from each side to slow
or stop it. The pads are shaped to cover a broad sector of the disc.
 There may be more than a single pair of pistons, especially in dual-circuit brakes.
 The pistons move only a tiny distance to apply the brakes, and the pads barely clear
the disc when the brakes are released. They have no return springs.
 When the brake is applied, fluid pressure forces the pads against the disc. With the
brake off, both pads barely clear the disc.
 Rubber sealing rings round the pistons are designed to let the pistons slip forward
gradually as the pads wear down, so that the tiny gap remains constant and the
brakes do not need adjustment.
 Many later cars have wear sensors leads embedded in the pads. When the pads are
nearly worn out, the leads are exposed and short-circuited by the metal disc,
illuminating a warning light on the instrument panel.

22. Drum brakes:
 A drum brake has a hollow drum that turns with the wheel. Its open back is covered
by a stationary backplate on which there are two curved shoes carrying friction
linings.
 The shoes are forced outwards by hydraulic pressure moving pistons in the brake's
wheel cylinders, so pressing the linings against the inside of the drum to slow or stop
it.
 With the brakes on, the shoes are forced against the drums by their piston.
 Each brake shoe has a pivot at one end and a piston at the other. A leading shoe has
the piston at the leading edge relative to the direction in which the drum turns.
 The rotation of the drum tends to pull the leading shoe firmly against it when it
makes contact, improving the braking effect.
 Some drums have twin leading shoes, each with its own hydraulic cylinder; others
have one leading and one trailing shoe - with the pivot at the front.
 This design allows the two shoes to be forced apart from each other by a single
cylinder with a piston in each end.
 It is simpler but less powerful than the two-leading-shoe system, and is usually
restricted to rear brakes.
 In either type, return springs pull the shoes back a short way when the brakes are
released.
 Shoe travel is kept as short as possible by an adjuster. Older systems have manual
adjusters that need to be turned from time to time as the friction linings wear. Later
brakes have automatic adjustment by means of a ratchet.
 Drum brakes may fade if they are applied repeatedly within a short time - they heat
up and lose their efficiency until they cool down again. Discs, with their more open
construction, are much less prone to fading.

24. Tyre Notations
HOW TO READ YOUR TYRE SIZE
Tyre Size Example
Example: 215/60R15
• 215 is the width of the tyre in
millimeters.
• 60 is the aspect ratio or tyre profile.
• R means it is radial construction.
• 15 is the diameter of the wheel rim in
inches.
Along with the manufacturer's name and the name of the tyre (e.g. Bridgestone Ecopia),
there's always a set of numbers and letters that relate to the size of the tyre. Here's a
rundown on what those numbers mean:
What's a tyre's profile?
This relates to the depth of the sidewall (the wall at the side of the tyre). The profile is
expressed as a percentage of the tyre's width. E.g. our 215/60R15 tyre has a profile or
sidewall that is 60% of the 215mm (width). A low profile tyre is generally 50% or below,
down to as little as 30% with ultra low profile tyres. Higher performance vehicles are
usually fitted with tyres that have lower profiles.
While low profile tyres give you greater control and better handling on corners, they can
give a slightly harder ride. Also, going to a lower profile on the same size wheels will alter
your speedometer reading so you'll need to fix that up before you hit the road.
Clutch & Flywheels

25. How the clutch works:
It transmits engine power to the gearbox, and allows transmission to be interrupted while a
gear is selected to move off from a stationary position, or when gears are changed while
the car is moving.
Most cars use a friction clutch operated either by fluid (hydraulic) or, more commonly, by
a cable.
When a car is moving under power, the clutch is engaged. A pressure plate bolted to the
flywheel exerts constant force, by means of a diaphragm spring, on the driven plate.
Earlier cars have a series of coil springs at the back of the pressure plate, instead of a
diaphragm spring.
The driven (or friction) plate runs on a splined input shaft, through which the power is
transmitted to the gearbox. The plate has friction linings, similar to brake linings, on both
its faces. This allows the drive to be taken up smoothly when the clutch is engaged.
When the clutch is disengaged (pedal depressed), an arm pushes a release bearing against
the centre of the diaphragm spring which releases the clamping pressure.
The outer part of the pressure plate, which has a large friction surface, then no longer
clamps the driven plate to the flywheel, so the transmission of power is interrupted and
gears can be changed.
Parts of the clutch:
The modern clutch has four main components: the cover plate (which incorporates a
diaphragm spring), the pressure plate, the driven plate, and the release bearing.

26. The cover plate is bolted to the flywheel, and the pressure plate exerts pressure on the
driven plate through the diaphragm spring or through coil springs on earlier cars.
The driven plate runs on a splined shaft between the pressure plate and flywheel.
It is faced on each side with a friction material which grips the pressure plate and flywheel
when fully engaged, and can slip by a controlled amount when the clutch pedal is partially
depressed, allowing the drive to be taken up smoothly.
The release bearing is pushed hard against the diaphragm spring, either hydraulically or by
a cable and lever, and releases spring load to interrupt power transmission.

28. Flywheel
 A flywheel is a rotating mechanical device that is used to store rotational energy. ... -
Providing continuous energy when the energy source is discontinuous.
 For example, flywheels are used in reciprocating engines because the energy source,
torque from the engine, is intermittent.
 A flywheel serves four main purposes (in most vehicles):
 It provides mass for rotational inertia to keep the engine in motion.
 It is specifically weighted to provide balance for the crankshaft.
 It provides a means to get the engine started (starter ring).
 It provides a connection for power transfer between the engine and transmission
(along with the clutch it also provides a means to interrupt the power flow).

29. Engine Dismantling
Dismantling Engine Into Sub-Assemblies:
 Installation on Assembly Stand
 Removal of Ignition Wires
 Spark Plugs
 Removing Cylinder Head and Inter-Cylinder Air Deflectors
 Draining Oil Sumps
 Removal of Accessories
 Removal of Gear case and Attaching Parts
 Removal of Breather Elbow and Tachometer Drive Housing
 Removing Idler Gear
 Removing Oil Sump
 Removal of Cylinders and Pistons
 Removal of Carburetor Air Heat Control Valve and Carburetor
 Removal of Thrust Nut, Thrust Cover, Oil Slinger, Crankcase Front Section and
Bearing Spacer
 Removal of Crankshaft and Master Rod Assembly from Crankcase Rear Section
 Removal of Crankcase Rear Section From Induction Housing
 Removal of Induction Housing From Assembly Stand
 Ignition Cables, Terminals, And Magneto Distributor Blocks

30.  Disassembly of Sub-Assemblies:
 Magneto and Coupling
 Magneto Drive
 Gear case
 Oil Pump
 Oil Sump
 Cylinders
 Pistons and Pins
 Carburetor Heat Control Valves
 Thrust Cover
 Crankcase Front Section
 Crankshaft And Master Rod Assembly
 Master Rod and Link Rods
 Crankcase Rear Section
 Induction Housing
 Cam Follower Guide

31. Differential
 The differential is an integral part of all four wheelers. Differential technology was
invented centuries ago and is considered to be one of the most ingenious inventions
human thinking has ever produced.
 A differential’s purpose can be broken down into three functions:
 Firstly, a differential takes the power from the engine and connects it with the
driving wheels.
 Secondly, a differential is the last gear reduction that will occur in the vehicle.
 Thirdly, the differential transmits the power from the engine to the wheels while
allowing the wheels to rotate at different speeds.
 A motor vehicle needs a differential because a vehicle’s wheels spin at different
speeds, especially during a cornering manoeuvre.
 If the car did not have a differential, the driving wheels would have to be locked
together and forced to spin at the same speed. Ouch! This would not only make
turning a nightmare and increase the chance of losing control, but it is also hard on

32. the vehicle. For the car to turn with the wheels locked, one tyre would have to slip.
The large force needed to make a tyre slip on tarmac is great and the force would
have to be transmitted through the axle from one wheel to the other, which would
put a huge strain on the axle componentry – not to mention the rubber!
Lubrication System
 Lubricating systems are used to introduce oil, grease and other lubricants to
moving machine parts. The lubricants reduce friction between parts, and therefore
increase the longevity of all components. Without lubrication, most machines would
overheat or suffer extreme damage.
 The Engine lubrication system is considered to give a flow to the clean oil at the
accurate temperature, with a appropriate pressure to each part of the engine. The
oil is sucked out into the pump from the sump, as a heart of the system, than forced
between the oil filter and pressure is fed to the main bearings and also to the oil
pressure gauge.
 The oil passes through the main bearings feed- holes into the drilled passages which
is in the crankshaft and on to the bearings of the connecting rod.
 The bearings of the piston-pin and cylinder walls get lubricated oil which
dispersed by the rotating crankshaft. By the lower ring in the piston the excess
being scraped. Each camshaft bearing is fed by the main supply passage from a
branch or tributary. And there is another branch which supplies the gears or timing
chain on the drive of camshaft. The oil which is excesses then drains back to the
sump, where the heat is being transferred to the surrounding air.

33.  Journal Bearings:
 If the crankshaft journals get worn, the engine will be having very low oil pressure
and will throw oil all over inside the engine.
 The unnecessary splash will overcome the rings and can cause the engine to use that
oil. Simply replacing the bearing inserts can restore the worn bearing surfaces.
 In well maintained engine, bearing wear take places instantly after a cold start
because there is less or no oil film between the shaft and bearing. At the time that
enough automotive lubricants is dispersed through the hydrodynamic lubrication
system apparent and stops the bearing wear progress.
 Piston rings – Cylinder:
 A sliding seal avoiding leakage of the air mixture or fuel is provided by piston
rings. It gets weaken into the oil sump while combustion and compression from the
combustion chamber.
 On other hand, from leaking into the combustion area they keep oil in the sump,
where it will be burned and lost.
 Hydrodynamic lubrication prevails in the center of the cylinder wall and the
piston rings of the good maintained car, essential for the very lower wear and
friction.
 The thickness of the film becomes assorted and minimal lubrication may exist where
the piston will stop to redirect on the top and bottom of the dead centre.
 To analyze or realize well head transfer from the piston to the cylinder, a finest
sealing, a minimal thickness of film and a minimum of oil burning is desirable.
 Oil controlling ring keeps minimal the thickness of film. This is ring is located after
the piston rings so that the surplus oil directly scraped down to the sump.
 To lubricate the following ring the oil film left on the cylinder wall by the passage of
this ring will be available.

34.  Oil degradation results by the air mixture or leakage of the fuel which exhaust
from the combustion chamber into the oil sump. That is why, frequent
replenish of oil despites, oil change will remain essential or it can also become
more essential.
Gear Box
 An automobile requires high torque when climbing hills and when starting, even
though they are performed at low speeds. On other hand, when running at high
speeds on level roads, high torque is not required because of momentum. So
requirement of a device is occur, which can change the vehicle’s torque and its
speed according to road condition or when the driver need. This device is known as
transmission box.
 Function of transmission box (gear box):
 The transmission box which is also known as the gear box is the second element
of the power train in an automobile. It is used to change the speed and torque of
vehicle according to variety of road and load condition. Transmission box change
the engine speed into torque when climbing hills and when the vehicle required.
Sometimes it is known as torque converter.

35.  Main functions of a gear box are as follow:
 Provide the torque needed to move the vehicle under a variety of road and load
conditions. It does this by changing the gear ratio between the engine crankshaft and
vehicle drive wheels.

Be shifted into reverse so the vehicle can move backward.

Be shifted into neutral for starting the engine.
 Main components of a gear box:
 In any device two or more component works together and fulfills the required
function. In a transmission box four components are required to fulfill its function.
These components are-
 Counter shaft:
 Counter shaft is a shaft which connects with the clutch shaft directly. It contains the
gear which connects it to the clutch shaft as well as the main shaft. It may be run
runs at the engine speed or at lower than engine speed according to gear ratio.
 Main shaft:
 It is the shaft which runs at the vehicle speed. It carries power form the counter shaft
by use of gears and according to the gear ratio, it runs at different speed and torque
compares to counter shaft. One end of this shaft is connects with the universal shaft.

36.  Gears:
 Gears are used to transmit the power form one shaft to another. They are most
useful component of transmission box because the variation is torque of counter
shaft and main shaft is depend on the gear ratio.
 The gear ratio is the ratio of the driven gear teeth to the driving gear teeth.
 If gear ratio is large than one, the main shaft revolves at lower speed than the
counter shaft and the torque of the main shaft is higher than the counter shaft.
 On other hand if the gear ratio is less than one, than the main shaft revolves at higher
speed than the counter shaft and the torque of the main shaft is lower than the
counter shaft. A small car gear box contains four speed gear ratio and one
reverse gear ratio.
 Bearings:
 Whenever the rotary motion, bearings are required to support the revolving part and
reduce the friction. In the gear box both counter and main shaft are supported by the
bearing.
 Working of a principle gear box:
 In a gear box, the counter shaft is mashed to the clutch with a use of a couple of
gear. So the counter shaft is always in running condition.
 When the counter shaft is bring in contact with the main shaft by use of meshing
gears, the main shaft start to rotate according to the gear ratio.
 When want to change the gear ratio, simply press the clutch pedal which disconnect
the counter shaft with engine and change connect the main shaft with counter shaft
by another gear ratio by use of gearshift lever.
 In a gear box, the gear teeth and other moving metal must not touch.
 They must be continuously separated by a thin film of lubricant. This prevents
excessive wear and early failure.

37.  Therefore a gearbox runs partially filled with lubricant oil.
Ignition System
The purpose of the ignition system is to generate a very high voltage from the car's 12
volt battery, and to send this to each sparkplug in turn, igniting the fuel-air mixture
in the engine's combustion chambers.
The coil is the component that produces this high voltage. It is an electromagnetic device
that converts the low-tension (LT) current from the battery to high-tension (HT) current
each time the distributor contact-breaker points open.
The distributor unit consists of a metal bowl containing a central shaft, which is usually
driven directly by the camshaft or, sometimes, by the crankshaft.
The bowl houses the contact-breaker points, rotor arm, and a device for altering the
ignition timing. It also carries the distributor cap.

38. Distributing the current:
The distributor cap is made of nonconductive plastic, and the current is fed to its central
electrode by the HT lead from the centre of the coil.
Inside the cap there are more electrodes often called segments to which the sparkplug leads
are connected, one per cylinder.
The rotor arm is fitted on top of the central shaft, and connects to the central electrode by
means of a metal spring or spring-loaded brush in the top of the distributor cap.
The current enters the cap through the central electrode, passes to the centre of the rotor
arm through the brush, and is distributed to each plug as the rotor arm revolves.
As the rotor arm approaches a segment, the contact-breaker points open and HT current
passes through the rotor arm to the appropriate sparkplug lead.
The contact-breaker points are mounted inside the distributor. They act as a switch, in
synchronisation with the engine that cuts off and reconnects the 12 volt low-tension (LT)
circuit to the coil.
The points are opened by cams on the central shaft, and are closed again by a spring arm
on the moving contact.
With the points closed, LT current flows from the battery to the primary windings in the
coil, and then to earth through the points.
When the points open, the magnetic field in the primary winding collapses and high-
tension (HT) current is induced in the secondary windings.
This current is transferred to the sparkplugs through the distributor cap.
On a four-cylinder engine there are four cams. With each full rotation of the shaft the
points open four times. Six-cylinder engines have six cams and six electrodes in the cap.
The position of the points and the distributor's body in relation to the central shaft can be
adjusted manually.
This alters the timing of the spark to obtain an exact setting.

39. Further changes occur automatically as the engine speed varies according to the throttle
opening.
In some modern ignition systems, micro-electronics ensure the optimum ignition timing for
all engine speeds and engine load conditions.

40. Completing the circuit:
The sparkplugs are screwed into the combustion chambers in the cylinder head.
HT current passes from each segment on the distributor cap down the plug leads to the
plug caps.
It then passes down the central electrode, which is insulated along its length, to the nose of
the plug.
A side electrode connected to the plug body protrudes just below the central one, with the
gap between the two usually set from 0.025 in. (0.6 mm) to 0.035 in. (0.9 mm).
The current sparks across this gap, flows along the side electrode, through the plug body
and the engine, then back to the coil, completing the circuit.

41. Fuel Supply System
The fuel supply system of the vehicle constitutes an important element of an engine. Its
core function is to ensure the smooth and uninterrupted supply of fuel to other
peripherals of an engine.
Components of Automobile Fuel Supply System :
Automobile Filters:
Automobile Filters are the devices or strainers generally tank or tubes used in automobiles
for separating impurities from gases or fluids. An automobile filter ensures that the fuel,
which is circulated in the engine, is filtered, clean and does not contain any waste material.
Filters are of many types such as:
Air Filters
Fuel Filters
Air Cleaner
Inline Filter
Oil Filters
Air Filter Assemblies
Fuel Filter Seal

42. Automotive LPG System:
It is that type of fuel system in which liquid fuel gas is converted into gaseous form by
adding heat into it.
Liquefied petroleum gas is considered to be the cleaner fuel, which produces fewer
emissions ultimately, leading to less oil contamination.
Automotive LPG System is categorized as:
LPG Fuel Tank
Carburetor:
Carburetor is an integral device or apparatus of an internal combustion engine that is used
for blending air fuel mixture in the correct proportion thereby resulting in smooth
combustion. It is that types of device which also controls and monitors the speed of the
vehicle. These are usually of two types namely surface carburetor and float-feed
carburetor.
Other parts of a Carburetor are:
Choke Cables
Carburetor Kits
Carburetor Components
Fuel Cells:
Fuel Cells often work similar like batteries; fuel cells are the electrochemical devices that are used
for converting chemical energy into electricity with the help of fuel.
Fuel cells are mostly created for electric automobiles as they emit less pollution. Automobile fuel
cells are mostly categorized on the basis of their operating temperature and electrolyte they use.
The different components that fuel cells comprise of:
Fuel Cell Caps
Fuel Cell Foam Inserts
Fuel Cell Tip-Over Valves
Fuel Cell Filler Valves
Fuel Cell Mounts
Fuel Coolers:
These are the devices or mediums that are used for cooling fluids distributed in an internal
combustion engine of the vehicle.

43. Fluid Coolers are the widely used devices as they reduce the rising temperature of variety of oil,
lubricants or fluids circulated within the engine.
Basically there are two types of fuel coolers namely:
Evaporative coolers Dry air coolers
Fuel Injection System:
Fuel Injection System is a mechanism through which fuel is injected or metered into the different
components of an internal combustion engine of the vehicle. Under this system, atomized fuel is
directly forced into the engine cylinders without making use of carburetors.
There are other components of fuel injection system used by automobile fuel supply system such as:
Diesel Fuel Injectors
Fuel Rails
Fuel Injection Systems
Throttle Body
Fuel Injectors
Electronic Fuel Injection
Fuel Injector Nozzle
Fuel Pump:
Fuel Pump are the devices that are used for supplying the fuel collected in the fuel tank to the
engine. Automobiles make use of two basic fuel pumps namely mechanical pump and electrical
pumps. Both of these fuel pumps are used for extracting gasoline from the fuel tank thereby
distributing to carburetor or injector pump.
Today, most of the vehicles use electric pumps because of their capacity of generating high pressures
that is required for fuel injection at all the engine speeds.
Fuel Pumps are of many types that includes:
Diesel Engine Fuel Pump
Mechanical Fuel Pump
Fuel Pump Assembly
Fuel Pump Kits
Electrical Fuel Pump
Fuel Pressure Regulators
Fuel Pump Filter
Water Pump Kits
Fuel Tank:
Fuel Tank is a large receptacle container specifically used for storing fuel in an automobile.
Fuel tanks are usually located at the rear position of a vehicle.
Fuel Water Separator:
Fuel Water Separator are the devices used by automobile for separating fuel and water so
that it does not enter engine and fuel induction components.
Intake Manifolds are categorized as:

44. EGR Valve
Intake Manifold Gaskets
Motor Mount Bolts
Nitrous Oxide System:
High performance nitrous oxide systems used in automobile produces more additional
horsepower by permitting engine of the vehicle to ignite more fuel than it normally burn.
Nitrous oxide used in the automobiles is generally kept in a metal tank or boot of the
vehicle. Nitrous oxide is a compound of nitrogen and oxygen, which when heated it breaks
into two different gases namely nitrogen and oxygen.
Nitrous Oxide System is categorized as:
AN to Pipe Thread Fittings
Bulkhead Fittings
Nitrous Oxide High Flow Tee Valve
Cap Fittings
Nitrous Oxide Bottles

46. Valve Mechanism
The valves in an engine have numerous functions:
First, they must permit the intake of fuel and air. Then they must seal compression.
After the explosion the exhaust valve must permit the burned gases to leave the
combustion chamber. Then there is one other function that valves must perform.
They must streamline these gases and make it possible for them to move into and out of the
combustion chamber as rapidly as possible, and, when the gases leave the combustion
chamber, they must be so directed that they will not swirl or congest in a manner that will
prevent the complete scavenging of the cylinder.
In four stroke internal combustion engine, the “Poppet Valve” performed the opening
of the cylinder to inlet or exhaust manifold at the correct moment.
Generally, the face of the valve is ground at 45 degrees but in same cases, it is ground at 30
degrees also.
It is not important to have a same angle of the face in inlet and exhaust valve of same
engines (valve mechanism).
To make it in the right order, the valve may be reground after some use. There is some
margin provided to avoid sharp edges.
The groove, retain the valve spring which aids in keeping the valve pressed against the seat
when closed and thus seal the combustion space tightly. In close position, the valve face
fits the accurately matched ground seat in the cylinder block.
Generally, replaceable ring inserts are used for exhaust valve seat.

47. Valve Mechanism of a Side Valve:
Poppet valve has following main parts:
01) Cam Shaft 02) Cam 03) Cam Follower 04) Tappet 05) Adjusting Screw 06) Washer
07) Valve Spring 08) Valve Stem 09) Valve Stem Guide 10) Valve Face
With the help of these parts, valve performs its operation very accurately in internal
combustion engine. The cam actuates the movement of the valve through the tappet.
The replaceable valve stem moves up and down in the valve stem guide. This movement
is obtained by rotation of camshaft and cam, which generally runs at the half the
engine speed.
The valve spring, keeps the valve pressed against its seat and ensure a leakage proof
operation and also bring back the valve very quickly during its closing (valve
mechanism).
When the engine is started, it gets heated up gradually thereby causing the valve stem to
expand.
A valve tappet clearance is always provided to allow the expansion of valve stem and
other parts. This clearance value depends upon the length of the valve, its material and the
operating temperature of the engine.
The tappet valve clearance can be adjusted by rotating the adjusting screw.
Where adjusting screw is not provided to vary the clearance, it can be increased by
grinding the bottom of the valve stem and face or by using the longer valve.
The clearance provided in exhaust valve is slightly more than that of the inlet valve. This is
due to slightly more expansion in exhaust valve because of higher temperature of hot
exhaust gases produced during combustion.

48. Valve Mechanism of Overhead Valve:
In this valve mechanism, a push rod and a rocker arm, to push the valve against the spring
pressure are required.
The rocker arm rotates about the rocker arm shaft under the force exerted by the push rod.
The clearance in this valve mechanism is kept between the rocker arm and the valve stem
and can be adjusted by the screw adjuster.
A suitable gear train or chain is provided to convert the drive from crankshaft to camshaft.
In high-speed engines, the frequency of vibration of the valve spring coincides with
the normal operating frequency of the valve which leads to resonance and increasing
the surging effect.
To overcome this problem, nowadays compound springs are used. Compound spring
means “One spring within the other of different natural frequencies”.

49. Compression Ratio
 Compression ratio is simply the volume of the cylinder and the volume of the
combustion chamber of the cylinder head when the piston is at Bottom Dead
Center (BDC) and the volume of the cylinder head combustion chamber when
the piston is at Top Dead Center (TDC).
 In other words, it's the ratio of compressed to uncompressed gas, or how tightly the
incoming fuel/air mix is squeezed into the combustion chamber before it's ignited.
The more it's squeezed, the more efficiently it burns and the more power is made.
 How does it affect fuel economy?
 The higher the ratio, the more compressed the air in the cylinder is. When the air is
compressed, you get a more powerful explosion from the air-fuel mixture, and more
of the fuel gets used.
 How does it affect Pollution or emission?
 High compression ratios provide better burning of fuel and this reduce the waste
gases produced by the engine, anything higher than 16:1 will be problem and create
something called a knock.
 Lower compression ratios allow you to burn bad quality fuel or lower octane fuel
thus increasing waste gases.
 How does it affect engine cold starting characteristics?
 Engines with high compression ratios produce excessive heat compared to lower
compressed vehicles thus doing a cold start should not be a problem for these type of
vehicles , in most motorcycles(with high compression ratio) not touching the throttle
while doing a cold start is very effective.
 As for a lower compressed engine the case is the same for any normal engine you
need it to heat up for a better start.

50.  How does it affect performance?
 This is a no brainer; higher compression ratios will provide much more power than
lower ratios that is why F1 cars have extremely high compression ratios.
 This also allows engine to be more efficient at higher rpms.
 Lower compression ratios give lower output but are easier to build, maintain and
generally have better life.
 Why would I go for higher compression?
 Much better performance.
 Higher "relative" fuel economy.
 Higher usable power throughout the rpms.
 Better emissions.
 Why would i go for lower compression?
 Much much cheaper to build, run and repair.
 Lasts much longer than counterpart.
 Can be air cooled.
 Less Noise, vibration.
 Better real world fuel economy.
 Runs on crappy fuel.
 Does not generate as much heat.

51. Engine Assembly (Chevy)
Step 1: Install Rear Oil Gallery Plugs and Freeze Plugs (Torque Fasteners)
Step 2: Install Rear Camshaft Plug
Step 3: The Big-Block Takes a Stand
Step 4: Install Front Oil Gallery Plugs
Step 5: Install Other Block Plugs
Step 6: Install Main Studs (if applicable)
Step 7: Install Main Bearings & Prepare Main Bolts
Step 8: Lubricate Cam Bearings
Step 9: Install Rear Main Seal
Step 10: Install Crankshaft
Step 11: Install Rear Main Cap (Torque Fasteners)
Step 12: Assemble Pistons with Floating Pins onto Connecting Rods
Step 13: Ring Gap Locations for Cylinders
Step 14: Install Oil Rings
Step 15: Install Compression Rings (Important!)
Step 16: Install Rod Bearings
Step 17: Ready to Install Piston/Rod Assembly
Step 18: Ring Compressor Choices and Procedures (Use Special Tool)
Step 19: Lubricate Piston and Rod Assembly
Step 20: End Gap Check and Compressor Install
Step 21: Installing the Piston (Professional Mechanic Tip)
Step 22: Identifying Piston/Rod Interference Issues (Important!)
Step 23: Continue Installing Piston
Step 24: Install the Rod Cap (Torque Fasteners)
Step 25: Check Rotation Torque (Torque Fasteners)
Step 26: Check Cylinder Wall (Torque Fasteners)
Step 27: Install Remaining Pistons and Check Torque (Torque Fasteners)
Step 28: Camshaft Lubrication (Use Special Tool)
Step 29: Camshaft Installation
Step 30: Install Timing Chain Cam Drive
Step 31: Bolt-on Cam Gear and Lube (Torque Fasteners)
Step 32: Install Timing Cover Seal
Step 33: Install Timing Chain Cover (Torque Fasteners)

52. Step 34: Harmonic Damper Install (Use Special Tool)
Step 35: Oil Pump and Shaft Install
Step 36: Install Oil Filter Adapter
Step 37: Prepare Oil Pan Gasket Surface
Step 38: Install the Front and Rear Pan Gaskets
Step 39: Install Side Rail Pan Gaskets
Step 40: Install Oil Pan (Torque Fasteners)
Step 41: Fel-Pro One-Piece Oil Pan Gasket
Step 42: Install Valve and Seal (Professional Mechanic Tip)
Step 43: Install Valve springs
Step 44: Prepare Heads, Gaskets, and Bolts
Step 45: Install Head Hardware
Step 46: Check Your Heads
Step 47: Cylinder Head Safety (Important!)
Step 48: Install Cylinder Heads
Step 49: Head Bolt Torque Sequence (Torque Fasteners)
Step 50: Install Lifters
Step 51: Install Pushrods
Step 52: Rocker Arm Installation
Step 53: Rocker Locking Nuts
Step 54: Adjust Valves
Step 55: Install Fuel Pump (Torque Fasteners)
Step 56:Pre-Oiling Checks
Step 57: Prepare Intake Manifold and Gaskets
Step 58: Apply Intake Manifold Silicone
Step 59: Install Intake Manifold
Step 60: Intake Manifold Torque Sequence (Torque Fasteners)
Step 61: Seal Open Ports
Step 62: Install Water Pump (Torque Fasteners)
Step 63: Install Valve Covers (Torque Fasteners)
Step 64: Install Thermostat and Housing (Torque Fasteners)
Step 65: Distributor Preparation
Step 66: Install Distributor
Step 67: Install Exhaust Manifolds (Torque Fasteners)
Step 68: Firing Order
Step 69: Install Spark Plugs and Ignition Wires
Step 70: Install Carburetor (Torque Fasteners)
Step 71: Install External Accessories (Torque Fasteners)
Step 72: Install Remaining Top Accessories3

53. Step 73: Install Flywheel or Flex plate (Torque Fasteners)
Step 74: Install Starter (Precision Measurement)

54. Electrical System
Automobile electrical system has gradually evolved over the years and today it assimilates
automatic computer control of the automotive mechanics.
In the early days, automobiles electrical system comprised of only basic wiring
technologies that were used for distributing power to other parts of a vehicle.
It had only switches, wires, relays and controlled motors as its key components but today’s
electrical system includes sensors, actuators, alternators, battery, oxygen sensors,
generator, starter solenoid, starter drive, high power electrical system and other devices.
Components of Automobile Electrical System:
Armature Automobile Battery Automobile Ignition System
Automobile Starting System: Automotive Computer Chips Automotive Electrical Wiring:
Charging System
Spark Plugs
Armature:
Armatures are the moving parts of an electric machine generally alternators, generator or
motors of a vehicle, which vibrates when electromotive force is produced.
Also known as the rotating part of a dynamo, armatures are generally fixed on ball
bearings and are mostly made of copper wire coiled around an iron core.
The major functions of armature are:
Firstly, to produce an electromotive force.
Secondly, to transmit current in a rotating machines and force in a linear machine.
Automobile Battery:
Automobile Battery refers to an electrochemical device comprising of primary and
secondary cells that are used for transforming chemical energy into mechanical energy.
Most of the vehicles today use ‘lead acid’ batteries.
Classification of various components of a battery includes:

55. Battery Boxes
Battery Cable Terminals
Battery Plates
Performance Batteries
Ground Straps
Battery Cable
Battery Control Systems
Battery Trays
Voltage Regulators
Battery Switches
Automobile Ignition System:
Automobile Ignition System constitute of various devices, tools and components that are
used for igniting the fuel in an internal combustion engine of a vehicle.
In this system, electric current is used for burning the mixture of air and fuel with the help
of coil, battery, and spark plug. Ignition system is assembled in only those automobile
engines, which operates with the help of petrol or gasoline.
The chief components of automobile starting system are:
Starter
Starter Solenoid
Starter Drive
Bendix Drive Starter
Automotive Computer Chips:
Automotive Computer Chips also known as super chip, automotive computer chips are
basically the integrated circuits made of semi conducting material that are used for storing
a new engine management program in the electronic control unit of the vehicle.
These chips stores the data used by engine control unit, for managing and controlling
the engine functions.
Oxygen sensor is one of the types of automobile computer chips that form an important
part of the engine fuel control feedback loop.
Automotive Computer Chips comprises of:
Engine Management Systems
Oxygen Sensors
Sensor Ring
Automotive Electrical Wiring:
The electrical wiring system of an automobile incorporate different types of devices,
flexible electrical wires, electrical fuses, connectors, fuse blocks used for fastening one end
of an automobile component to the power source device.
These electrical wiring components are used for bearing mechanical loads and transmitting
communication signals or electrical energy.

57. Air Conditioning System
Air conditioning is the process of treating air control simultaneously its temperature,
humidity and to meet the requirements of conditioned space.
Air conditioner systems are designed to allow the driver or passenger feel more
comfortable during uncomfortably warm humid or hot trips in a vehicle.
NEED OF AUTOMOTIVE AC SYSTEM:-
To build up comfort zone for passengers
Required for cooling engine & other parts
Components:
Compressor: The compressor is the work horse of the air conditioning
system, powered by a drive belt connected to the crankshaft of the engine. When
the air-condition system is turned on, the compressor pumps refrigerant vapour
under high pressure to the condenser.
Condenser: The condenser is a device used to change the high-pressure refrigerant
vapor to a liquid. It is mounted in front of the engine's radiator, and it looks very
similar to a radiator. The vapour is condensed to a liquid because of the high
pressure that is driving it in, and this generates a great deal of heat. The heat is
then in turn removed from the condenser by air flowing through the condenser on
the outside.
Receiver: The now liquid refrigerant moves to the receiver-dryer. This is a small
reservoir vessel for the liquid refrigerant, and removes any moisture that may have
leaked into the refrigerant. Moisture in the system causes havoc, with ice crystals
causing blockages and mechanical damage.
Expansion Valve: The pressurized refrigerant flows from the receiver-drier to the
expansion valve. The valve removes pressure from the liquid refrigerant so that it
can expand and become refrigerant vapour in the evaporator.
Evaporator: The evaporator is another device that looks similar to a car radiator. It
has tubes and fins and is usually mounted inside the passenger compartment
behind the fascia above the foot well. As the cold low-pressure refrigerant is passed
into the evaporator, it vaporizes and absorbs heat from the air in the passenger

58. compartment. The blower fan inside the passenger compartment pushes air over
the outside of the evaporator, so cold air is circulated inside the car. On the 'air-
side' of the evaporator, the moisture in the air is reduced, and the 'condensate' is
collected and drained away.
Compressor: The compressor then draws in the low-pressure refrigerant vapour to
start another refrigeration cycle. The refrigeration cycle then runs continuously, and
is regulated by the setting of the expansion valve.
The whole process is reasonably simple when explained like that. All air conditioning
systems work on the same principle, even if the exact components used may vary
slightly between car manufacturers.

59. Mileage
What is Mileage or Fuel Efficiency?
Mileage indicates the distance that a vehicle can travel with a specific amount of fuel
(i.e. Total number of kilometers/miles on the odometer).
The car that can travel a good distance with just a small amount of fuel is stated as a
vehicle with good mileage or high fuel efficiency, which also means that the owner of that
car need not spend much money on expensive petrol or diesel.
Especially in the last few years, car and bike mileage has become a focus of attention of
drivers and manufacturers since petrol, diesel and other fuels have become quite expensive.
How should you measure the mileage of your car?
These days calculating the mileage of your car has become simple and easy with the
help of your odometer.
Fill the fuel tank of your car till the rim and reset your odometer to the zero point. Now, do
a drive that represents your normal activity, while ensuring it's significantly long enough.
After, that fill your tank again till the brim, while noting the number of liters that you have
tanked.
You can now calculate your car's mileage (or fuel economy) by dividing the number of
kilometers that you have driven by the number of liters of fuel that filled the second time.
The result is the "kilometer per liter" or mileage of your car.
What determines the fuel efficiency of your vehicle?
The analysis of a vehicle's mileage is a very important one. To understand why some
vehicles need more fuel to drive one kilometer of distance (the car's fuel efficiency), is a
technical analysis.

60. Some reasons for bad mileage is weight of the car, the age of the car, the maintenance of
the vehicle, the traffic conditions, the fuel type and quality and the driving style. In general
we can say that the calm and controlled driver can get better mileage.
So who cares about mileage?
Government and consumer agencies are very keen to ensure that consumers understand
the car's mileage, as manufacturers are always keen to overstate it.
So in current law, the ARAI of India will inform you what your car's mileage is from
independent tests.
What are average mileages?
For cars, mileages should be anywhere between 5KMPL to 25KMPL under normal
circumstances.

61. Piston
The piston transforms the energy of the expanding gasses into mechanical energy.
The piston rides in the cylinder liner or sleeve. Pistons are commonly made of aluminum
or cast iron alloys.
To prevent the combustion gasses from bypassing the piston and to keep friction to a
minimum, each piston has several metal rings around it.
These rings function as the seal between the piston and the cylinder wall and also act to
reduce friction by minimizing the contact area between the piston and the cylinder wall.
The rings are usually made of cast iron and coated with chrome or molybdenum.
Most diesel engine pistons have several rings, usually 2 to 5, with each ring performing a
distinct function:-
The top ring(s) acts primarily as the pressure seal.
The intermediate ring(s) acts as a wiper ring to remove and control the amount of oil film
on the cylinder walls.
The bottom ring(s) is an oil ring and ensures that a supply of lubricating oil is evenly
deposited on the cylinder walls.

62. Crank
A crank is an arm attached at a right angle to a rotating shaft by which reciprocating
motion is imparted to or received from the shaft.
It is used to convert circular motion into reciprocating motion, or vice versa. The arm may
be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end
of the crank by a pivot is a rod, usually called a connecting rod.
Connecting Rod
A connecting rod is an engine component that transfers motion from the piston to the
crankshaft and functions as a lever arm.
In a reciprocating piston engine, the connecting rod connects the piston to the crank or
crankshaft. Together with the crank, they form a simple mechanism that converts
reciprocating motion into rotating motion.
In modern automotive internal combustion engines, the connecting rods are most usually
made of steel for production engines, but can be made of T6-2024 and T651-7075
aluminum alloys (for lightness and the ability to absorb high impact at the expense of
durability) or titanium.
The piston pin, or wrist pin, provides a pivot point between the piston and connecting rod.

63. Bearings
Bearing is a device that is used to enable rotational or linear movement, while reducing
friction and handling stress.
Resembling wheels, bearings literally enable devices to roll, which reduces the friction
between the surface of the bearing and the surface it’s rolling over.
It’s significantly easier to move, both in a rotary or linear fashion, when friction is reduced
—this also enhances speed and efficiency.
How Bearings Work:
In order to serve all these functions, bearings make use of a relatively simple structure: a
ball with internal and external smooth metal surfaces, to aid in rolling. The ball itself
carries the weight of the load—the force of the load’s weight is what drives the bearing’s
rotation. There are two different kinds of loading: radial and thrust.
A radial load, as in a pulley, simply puts weight on the bearing in a manner that causes the
bearing to roll or rotate as a result of tension.
A thrust load is significantly different, and puts stress on the bearing in an entirely different
way.
Many bearings are prone to experiencing both radial and thrust loads.

64. Types of Bearings:
Ball Bearings:
Ball bearings are extremely common because they can handle both radial and thrust loads,
but can only handle a small amount of weight.
They are found in a wide array of applications, such as roller blades and even hard drives,
but are prone to deforming if they are overloaded.
Roller Bearings:
Roller bearings are designed to carry heavy loads—the primary roller is a cylinder, which
means the load is distributed over a larger area, enabling the bearing to handle larger
amounts of weight.
This structure, however, means the bearing can handle primarily radial loads, but is not
suited to thrust loads.
Ball Thrust Bearings:
These kinds of bearings are designed to handle almost exclusively thrust loads in low-
speed low-weight applications.
Bar stools, for example, make use of ball thrust bearings to support the seat.
Roller Thrust Bearings:
Roller thrust bearings, much like ball thrust bearings, handle thrust loads. The difference,
however, lies in the amount of weight the bearing can handle: roller thrust bearings can
support significantly larger amounts of thrust load, and are therefore found in car
transmissions, where they are used to support helical gears.
Gear support in general is a common application for roller thrust bearings.

65. Tapered Roller Bearings:
This style of bearing is designed to handle large radial and thrust loads—as a result of their
load versatility, they are found in car hubs due to the extreme amount of both radial and
thrust loads that car wheels are expected to carry.
Specialized Bearings
There are, of course, several kinds of bearings that are manufactured for specific
applications, such as magnetic bearings and giant roller bearings.
Magnetic bearings are found in high-speed devices because it has no moving parts—this
stability enables it to support devices that move unconscionably fast.
Giant roller bearings are used to move extremely large and heavy loads, such as buildings
and large structural components.

66. Antilock Braking System
An anti-lock braking system or anti-skid 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.
ABS was introduced in the mid -1980s and has become "standard" equipment on the
majority of vehicles sold in Canada.
ABS in cars and most multi-purpose vehicles (MPV’s) and pick-up trucks works on all
four wheels.
How does it work?
ABS uses wheel speed sensors to determine if one or more wheels are trying to lock up
during braking. If a wheel tries to lock up, a series of hydraulic valves limit or reduce the
braking on that wheel. This prevents skidding and allows you to maintain steering control.

67. Advantages of Anti-Lock Brakes:
Stopping on ice: As mentioned above, an ABS prevents lock-ups and skidding, even in
slippery conditions. Anti-lock brakes have been proven to save lives in some situations by
helping drivers keep control of a vehicle.
Lower insurance costs. Because it is a thoroughly tested safety device with a track record
of effectiveness, insurers often give customers specific discounts for having an ABS
system on their vehicle.
Higher resale value: As a feature on a car or truck, an ABS raises the market value of the
vehicle. Nowadays, where ABS technology has become standard on many vehicles, not
having it could result in a lower price for resale.
Traction control: An ABS shares some of the infrastructure of a traction control system,
where new technology helps ensure that each wheel has traction on the road. That makes it
easy for manufacturers to install both of these features at the factory.

68. Disadvantages of Anti-Lock Brakes:
Despite the fact that anti-lock brakes are proven to be a safety feature in most situations,
and insurers consider them to significantly lower risk for a vehicle, not all drivers are sold
on this option for a car or truck. Here are some of the down sides that drivers find in this
kind of brake system:-
Inconsistent stop times: Anti-lock brakes are made to provide for surer braking in slippery
conditions. However, some drivers report that they find stopping distances for regular
conditions are lengthened by their ABS, either because there may be errors in the system,
or because the clunking or noise of the ABS may contribute to the driver not braking at the
same rate.
Expense: An ABS can be expensive to maintain. Expensive sensors on each wheel can
cost hundreds of dollars to fix if they get out of calibration or develop other problems. For
some, this is a big reason to decline an ABS in a vehicle.
Delicate systems: It's easy to cause a problem in an ABS by messing around with the
brakes. Problems include disorientation of the ABS, where a compensating brake sensor
causes the vehicle to shudder, make loud noise or generally brake worse.

69. Air Bags
Airbags are balloon-like devices that expand when a car experiences a collision, providing
a cushion of air that prevents a person bashing their face on the dashboard or steering
wheel and suffering concussion, disfigurement or worse.
*The proper name for airbags is “Supplemental Restraint System (SRS)” airbag, and, as
their name suggests, are devices that supplement the operation of the seat belts. Only when
passengers have their seat belts properly fastened, will the airbags be fully effective.
The driver side airbag is located in the center of the steering wheel and the passenger side
airbag is located inside the dashboard.
How Do Airbags Work?
Airbag systems typically consist of multiple sensors, a control module, and at least one
airbag.
The sensors are typically placed in positions that are likely to be compromised in the event
of an accident, and data from accelerometers, wheel speed sensors, and other sources can
also be monitored by the airbag control unit.
If specific conditions are detected, the control unit is capable of activating the airbags.

71. New Technologies Introduced
The market may be slow but new technologies for vehicles are appearing at a
blistering pace.
Most are in the realm of safety, but some are pure convenience.
Typically, innovative features from the manufacturers are offered on higher-end cars as
options and eventually trickle down to less expensive vehicles as cost declines, awareness
increases and demand grows.
Equipment and features the public takes for granted today -- electric ignition, automatic
windshield wipers, power steering, airbags, cruise control and many more -- began life as
unexpected advances that dazzled the public.
When GM introduced the first automatic transmission -- its Hydra-Matic Drive -- in the
1940 Oldsmobile, it was a $57 option and more of a curiosity than a "gotta-have" feature.
Today automatic transmissions have advanced to the point of providing as many as eight
forward gears, driver-shift options, computerized driver-adaptable shifting and different
shifting modes, such as "sport," "touring" and "snow."
But in 1940, not stirring the transmission yourself was a radical concept and only well-
heeled risk takers ponied up the extra cash for the new technology.
Today's "cutting edge" is tomorrow's "commonplace." Here is a collection of technologies
already offered that could be mainstream just a year or two from now.

72. 8 great new car gadgets:
Rear-mounted radar.
Night vision with pedestrian detection.
Automatic high-beam control.
Parental control.
GPS vehicle tracking.
Cameras.
Driver capability.
In-car Internet.