SJP POLYTECHNIC DAMLA

Branch – Mechanical Engineering

Semester – 6th

Subject – Automobile Engineering

Code – 121763

CHAPTER - Introduction

Automobiles have around more than 100 year – Originally

called horseless carriages

Today more than 130 million cars in the U.S.– One-third of cars

in the world.

Source of employment for one in nine workers

Americans drive 7,767 miles per year

Automobiles include several systems – Body and suspension,

engine, electrical, etc.

Body and Chassis

• Chassis supports the engine and body

– Suspension

– Frame

– Brakes

– Steering

• Four-stroke cycle

– Intake stroke

• Piston is pulled down by crankshaft

– Compression stroke

• Both valves close and piston moves up

– Power stroke

• Burning fuel expands and forces piston down

– Exhaust stroke

• Piston moves up and forces exhaust out

Engine Support Systems

• Cooling system

– Cools the engine to prevent overheating

• Fuel system

– Carburetor

– Gasoline fuel injection

– Diesel fuel injection

• Lubrication system

– Moves pressurized oil to all engine areas

• Electrical system

– Ignition system

– Starting system

– Charging system

– Computer system

• Exhaust system

– Carries exhaust from engine to rear of car

• Emission control system

– Reduces or eliminates pollutants in exhaust

The Power train

• Transmits engine power to wheels

– Transmission (transaxle)

– Clutch

– Torque converter

– Differential

– Axles or half-shafts

• Front-wheel drive, rear-wheel drive, or all-wheel drive

• Manual or automatic

• Manual transmission

– Gears change leverage or torque

– Clutch uncouples powertrain from engine

• Automatic transmission

– Gears shifted based on speed and engine load

• Drive shaft

– Used on rear-wheel drive cars to transfer power to the rear

axle

– Hollow metal tube with universal joint at each end

• Rear axle assembly

– Drive axles power each rear wheel and a differential assembly

• Transaxle

– Used on front-wheel drive vehicles

– Transmission and differential in one housing

Accessory Systems

• Also called comfort systems

– Air conditioning

– Heating

– Power seats

– Power windows

– Cruise control

– Navigation, sound systems, etc.

History and Development of the Automobile

• Steam-powered vehicles

– First autos

– Powered by steam engine

– Developed in 1698

– Steam engine is an external combustion engine

• Early gasoline engines

– 1876: Dr. Nicolas Otto patented the slow-speed, four-stroke,

internal combustion engine

– 1885: Gottlieb Daimler patented high-speed, petroleum engine

– 1893: Benz shown at the World’s Fair in Chicago

– 1920: 90% of cars looked like carriages

– 3.8 million miles of road in the U.S. has been developed in less

than 100 years

CHAPTER: STEERING SYSTEM

CONTENTS

Steering System

Steering linkage

Akerman’s Steering mechanism

Davis Steering mechanism

Types of steering gears

Power steering

Adjustment of wheel

STEERING SYSTEMS

The steering gear changes the rotary motion of the

wheel into linear motion of the steering linkage.

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Steering System directs the vehicle in particular

directions.

It provides directional control of the vehicle to the

driver.

STEERING LINKAGE

Connects the linear motion of the steering gear to the steering

arms.

Parallelogram type linkage (typical) – 4

Pitman arm

Idler arm

Center link

Inner tie rod

Outer tie rod

Tie rod adjustment sleeve

PRINCIPAL AND FUNCTION OF ACKERMAN’S STEERING MECHANISM

It is based upon four-bar chain.

The two opposite links AC and MN are unequal; AC being longer than MN.

Two opposite links AM and CN are equal in length.

When the vehicle is moving on a straight path link AC and MN are parallel to each other.

The shorter links AM and CN are

inclined at angle a to the

longitudinal axis of the vehicle as shown (a)

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AB and CD are stub axles but integral part of AM and CN such

that BAM and DCN are bell-

crank levers pivoted at A and C.

Link AM and CN are known as

track arms and the link MN as

track rod.

The track rod is moved towards

left or right hand sides for

steering.

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For steering a vehicle on right hand side, link NM is moved towards left hand side with the result that the link CN turns clockwise. Thus, the angle a is increased and that on the other side, it is decreased.

Principle and Function of Davis Steering Mechanism

It consists of the main axle AC having a parallel bar MN at a distance h.

KAB and LCDare two bell-crank levers pivoted with the main axle at A and C respectively such that angle BAK and angle DCL remain constant.

Arms AK and CL have been provided with slots and these house die-blocks M

and N.

With the movement of bar MN at the fixed height, it is the slotted arms AK and CL which side relative to the die-blocks M and N.

In Fig. (a), the vehicle has been shown as moving in a straight path and both the

slotted arms are inclined at an angle a as shown.

Now suppose, for giving a turn to the right hand side, the base MN is moved to the right side by distance x.

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8

The bell-crank levers will change to the positions shown by dotted lines in Fig.(b).

The angle turned by the inner wheel and the outer wheels are and respectively.

The arms BA and CD when produced will meet say at I, which will be the

instantaneous center.

TYPES OF STEERING GEARS

Worm and nut

Worm and wheel

Worm and roller

Rack and pinion

WORM AND NUTS

WORM AND WHEELS

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WORM AND ROLLER STEERING GEAR

RACK AND PINION SYSTEMS

• Fewer parts and Light in weight • Modular and Saves space • Generally not as strong as a recirculating-ball type

system

POWER STEERING

POWER STEERING

CAMBER AND CASTER

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KINGPIN INCLINATION

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CHAPTER – BRAKING SYSTEM

CONTENTS

Introduction

Function of Braking System

Types of Braking System

Mechanical Braking System

Hydraulic Braking System

Air Braking System

Vaccum Braking System

Brake Adjustment

Anti Lock Braking System

INTRODUCTION

Brake is a device used for slowing ,stopping &

controlling the vehicle.

Braking operation based on kinetic energy of

vehicle is

to converting into heat, which dissipated into atmosphere.

While driving the vehicle, torque of the engine

produces

The tractive effort due to periphery of driving vehicle.

When the brakes are applied it produces negative tractive

effort on wheel.

While, this help to slow down an vehicle

MAIN FUNCTIONS OF BRAKING SYSTEM

To stop the vehicle

safely in shortest

possible distance in

case of emergency.

To control the

vehicle when it is

descending along

the hills

To keep the vehicle in

desired position after

bringing in at rest

TYPES OF BRAKING SYSTEM

Mechanical Braking System

Hydraulic Braking System

Air Braking System

Vacuum Braking system

Anti lock Brake System

MECHANICAL BRAKING SYSTEM

Classification

Mechanical Braking System, brakes are available in following construction

1.Drum type

2.Disc type Drum type Brake

There are generally of two types

Internal expanding drum brake.

External expanding drum brake.

INTERNAL EXPANDING BRAKE DRUM

Construction.

In Internal Expanding Drum Brake consist of leading shoe, anchor, adjustor, Heel of shoe, trailing shoe, brake retracting spring brake shoe, brake shoe,toe shoe etc.

In internal expansion b raking system brake liners are expands internally

Its consist of stationary plate,two

shoes hinged at anchor pins, and cam system to expand the shoe and a retracting spring.

EXTERNAL CONTRACTING

BRAKE DRUM

Construction

IN external contracting brake drum has brake drum is used for only

parking purpose .this system consist of Drum, brake & lining, operating

lever with adjusting lever and push rod with returning spring.

External braking system is model braking system used to operate in floor

mills, various types of electrical components. the following various types of

parts is applied on brake drum..

DISC TYPE BRAKE

CONSTRUCTION

DISC Brake consist of cast iron disc bolted to the wheel hub and an stationary housing called “caliper”. The caliper is connected with some stationary part of position of vehicle, like stub or axle on of wheel of connecting rod .

The piston rod is connected in between which has friction pad is being held

by an piston pins, springs etc.

HYDRAULIC BRAKING SYSYTEM

construction

hydraulic braking system is mainly confined with “brake fluid” this fluid consist of Alcohol,castor oil & glycerin.hydraulic braking system has following components.

master cylinder,brake pedal,wheel cylinder,brake drum,retracting spring,brake shoe etc.

The brake pedal is connected to the master cylinder by means of piston for application of brake driver presses the brake pedal, which moves the master cylinder.

In master cylinder pressure is instantly transferred to all four wheels. The brakes shoe moves against the brake drum to apply brakes.

WORKING SYSTEM

When driver releases the brake pedal, the master cylinder piston returns to its original position due to return springs, dropping fluid pressure. Brake shoe retracting spring pulls the brake shoe from drum to their original position & brakes are released.

ROLE OF MASTER CYLINDER:

To build the hydraulic pressure required to operate the system.

To bleed or force air out of brake line & wheel cylinder.

A to act reservoir to maintain a constant volume of fluid in system

ADVANTAGES OF HYDRAULIC BRAKE

simple in construction :Mechanical joints, linkages & cam are eliminated.

Equal braking system: the brake fluid must exists equal pressure.

Disadvantages of Hydraulic Brake

Fails whole system at one time: if there is leakages in system, all four brakes are fail at one time due to loss of fluid pressure. This difficulty can be eliminated with use of tendum master cylinder

PNEUMATIC / AIR BRAKING SYSTEM

Air Compresor

Its composes of generally Build

the air pressureby driven of engine.

Unloader Valve:

Its is device maintain constant

pressure in reservoir.The excess

of pressure is safely removed.

Reservoir:

it’s a tank in which

high pressure air is stored

Brake Valve:

its is located between air reservoir and brake cylinder

Relay valve:

It is valve kept in between brake

chamber & air chamber for

controlling the air chamber

VACCUM BRAKING SYSTEM

The vacuum brake was,

for many years, used in

place of the air brake as

the standard, fail-safe,

train brake used by

railways.

The vacuum brake system

is controlled through a

brake pipe connecting a

brake valve in the driver's

cab with braking

equipment on every

vehicle. Parts of Vaccum Braking System

A vacuum is created in

the pipe by an ejector or exhauster.

• Driver's Brake Valve • Exhauster • Vaccum Brake Pipe • Vaccum Reservoir • Ball Valve • Brake Cylinder

CONCEPT OF BRAKE ADJUSTMENT

Many vehicles come equipped with drum brakes. For many years, disc

brakes have been used at the front of the vehicles while drum brakes are

used at the rear.

Drum brakes can last a very long time, if maintained properly. Periodic

adjustment of the drum brakes makes sure that the brakes do not drag when

driving as this can rob power from the vehicle and cause the brakes to wear

out much more quickly.

Drum brakes usually need to be adjusted when the brake pedal has to be

pressed down a lot before the brakes engage. Adjustments can be done only on

brakes that are in good shape. Keep in mind that not all drum brakes are

adjustable. To confirm your brakes are in good working order before you adjust

them, check your vehicle

for symptoms of a bad or failing drum brake.

ANTILOCKING BRAKING SYSTEM {ABS}

SOURCE: INTERNET

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

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

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

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

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

systems. It does this at a much faster rate and with better control than a driver could manage

ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, ABS can significantly increase braking distance, although still improving vehicle control.

CHAPTER: SUSPENSION SYSTEM

CONTENTS

Introduction To Suspension System

Purpose Of Suspension System

Basic Parts

Springs

Leaf Spring

Coil Spring

Shock Absorbers

Air Suspension

INTRODUCTION TO SUSPENSION SYSTEM

What is suspension system?

Suspension is the term given to the system of

springs, shock absorbers and linkages that

connects a vehicle to its wheels Serve a dual purpose – contributing to the

car's handling and braking. Protects the vehicle itself and any cargo or

luggage from damage and wear

INTRODUCTION TO SUSPENSION SYSTEM

• Supports the vehicle and cushions the ride

– Holds tire and wheel in correct position

• Sprung weight

– Weight supported by car springs

• Powertrain, body, and frame

• Anything carried by the weight of springs

• Unsprung weight

– Reducing unsprung weight increases control

• Tires, wheels, brakes, bearings, axels, and differential

PURPOSE OF SUSPENSION SYSTEM

•Supports the weight.

•Provides a smooth ride.

•Allows rapid cornering

without extreme body roll.

•Keeps tires in firm contact

with the road.

•Allows front wheels to turn side-to-side for steering.

•Works with the steering system to keep the wheels in

correct alignment.

•Isolate passenger and cargo from vibration and shock

BASIC PARTS

Control Arm:- movable lever that fastens

the steering knuckle to the

vehicle’s

body or frame.

Steering Knuckle:– provides a

spindle or bearing support for the

wheel hub, bearings and wheel

assembly.

BASIC PARTS

Ball Joints:– swivel joints that allow control arm and steering

knuckle to move up and down and

side to side.

Springs:– supports the weight of

the vehicle; permits the control

arm and Wheel to move up and

down.

BASIC PARTS

Shock absorbers or

dampeners:- keeps the suspension from continuing to

bounce after spring compression

and extension.

Control arm bushing :–

sleeves that allows the control arm to swing

up and down on the frame.

SPRINGS

Support the load of the car

Absorb the up-and-down motion of wheels

Coil spring: most common spring used in front and rear of passenger cars

Variable rate spring: becomes stiffer as compressed

Smoother ride over small bumps

SPRINGS (CONT'D.)

• Leaf spring: long, flat strip of spring steel rolled at both

ends to accept rubber insulated bushing

– As leaf spring is deflected it becomes stiffer

• Air spring: rubber air chamber attached by tubing to an air

compressor

Fig. Leaf spring

Fig. Bump condition

Non-

Independent suspension

Independent

Suspension

LEAF SPRING

Used in many early

applications

Internal friction

provides damping

Provide Lateral

location for the axle Heavy

Fig. Multi LEAF SPRING

Prone to weaken

over time

Leaf springs are

now limited to the

rear of some cars

Fig. COIL SPRING AND LEAF SPRING

COIL SPRING

Little to no internal

damping Low cost Compact Size Used in many

Suspension types Coil spring is the

most common type

of spring found on

modern vehicles

Fig. COIL SPRING

SHOCK ABSORBERS

•A shock absorber is a mechanical device designed to smooth

out or damp shock impulse, and dissipate kinetic energy.

•Limits spring compression-

extension

movements to smooth the

vehicle’s ride.

•Without shock absorbers, the

vehicle would continue to

bounce up and down long after

striking dip or hump in the road.

Strut assembly (MacPherson struts)

SHOCK ABSORBERS

One at each vehicle corner

Dampen spring oscillations

Convert spring energy into heat energy

Poor shock absorbers

Aggravate SUV rollovers

Especially top-heavy vehicles

HYDRAULIC SHOCK ABSORBER

OPERATION

• One end attached to suspension

– Other to car body or frame

• Force oil through passageways controlled by valves

– Generates hydraulic friction

– Converts motion energy into heat energy

• Two chambers with piston

– Forces fluid through valve from one chamber to the other

• Either twin-tube or monotube

AIR SUSPENSION

Air suspension:- Air

Suspension is a type of vehicle

suspension powered by an

electric or engine driven air

pump

or compressor. This compressor

pumps the air into a flexible

bellows, usually made from

textile-reinforced rubber. This in

turn inflates the bellows, and

raises the chassis from the axle.

Pneumatic Spring On

Semitrailer

AIR SHOCKS/LEVELING DEVICES

Shocks not designed to carry vehicle weight

Some aftermarket devices use shock absorbers to correct vehicle height

Air shocks

Coil springs mounted on outside of shock body

Disadvantages of leveling vehicle using shocks

Shocks and shock mounts prone to breakage

Coil spring shock prevents body roll

ADVANTAGES:

•These maintain a constant frequency of

vibration whether the vehicle is laden or

unladen. •Constant frame height is

maintained.

•It helps to reduce the load while the vehicle in

motion i.e. the dynamic loading as the spring rate

variation between laden and unladen weight is

much less.

•It gives smooth and comfort ride of the vehicle.

•The stiffness of the system increases with the

increase of the deflection.