Layout

Introduction to Automobile

The Layout

-by Atul Katti

Components of an Automobile• The basic structure

• The power unit

• The transmission system

• The auxiliaries

• The controls

• The superstructure

The Basic Structure (Chassis)• This is the unit on which the other units are

mounted.

• It consists of:-– Frame– The Suspension system– Axles– Wheels – Tyres

1. Frame• There consists of two distinct forms

construction in common use:

1. The conventional pressed steel frame to which all units are mounted

2. The integral or frameless construction, in which the body structure is so designed so as to combine the functions of body and frame.

Frameless - Advantages• Reduced weight and consequent saving in fuel

consumption

• Lower manufacturing costs

• Safety to passengers

• Increased stability of the automobile

Disadvantages • Reduction in strength and durability

• Economical only if it is adopted in mass production

• Increased cost or repairs

• Convertible cars are difficult to design in frameless construction

2. Suspension System• The objects of the suspension are:– To prevent the road shocks from being

transmitted to the vehicle components

– To safeguard the occupants from road shocks

– To preserve the stability of the vehicle while in motion

Leaf Springs

Suspension system

Suspension system• There are two distinct types of suspension

systems:– The conventional system, in which the road

springs are attached to a rigid beam axle.

– The independent system, in which there is no rigid axle beam and each wheel is free to move vertically

Suspension system

3. Axles• It is the wait carrying members, may be on the

rear or front, are beams supported at ends.

• Axles are subjects to different kin of loads:– Vertical load due to self weight– A fore and aft load due to driving and braking– Torque reactions due to drive and brake– Side thrust due to centrifugal force during conference

Axles• There are three different types live rear axles

a) Fully floating type

b) Three quarter floating type

c) Semi-floating type

4. Wheels • Different types of wheels have been used in

automobiles over generations according to the requirement

Wire-spoked wheels

Pressed steel wheels

Light alloy wheels

The Power Plant (Engine)• The engine provides the power to move the

vehicle

• It generally consists of an IC engine, either SI or CI

• Gas turbines also have been used in vehicles

• Now, electric batteries for propelling the vehicle

The Transmission System• The transmission system consists of a– Clutch,

– Gear box,

– Propeller shaft, and

– Differential

Layout of the transmission system

The Transmission System• The functions of a transmission system are:– To disconnect the engine from road wheel when

desired

– To connect the engine to the driving wheels without shock

– To vary the leverage between the engine and the driving wheels

The Transmission System

– To reduce the engine speed permanently in a fixed ratio

– To turn the drive through a right angle

– To make provision for the flexing of the road springs

The Transmission System• The various components which perform the

above mentioned functions are:– Clutch:- To disengage the system from the engine

and to engage without shock to road wheels

– Gear box:- Provides the necessary leverage variation between the engine and road wheels

The Transmission System– Bevel pinion and crown wheels:- They turn the drive

round through 90° and also provide permanent reduction in speed

– Universal joints:- Provide for the relative movement between the engine and the driving wheels due to flexing of road springs.

– Differential:- Helps to attain different speeds at different wheels while taking a turn

The different types of the arrangement of transmission could be

• Front engine and front wheel drive

• Rear engine and rear wheel drive

• Front engine and four wheel drive

Different types of arrangements

Front engine FWD• The power is transmitted to front axles, from

the front engine (Front Wheel Drive)• A few advantages are:

i. The propeller shaft is eliminated. This permits low chassis height

ii. The pulls the car than pushing it, avoiding skidding tendency.

iii. Better road adhesion.

FWD

Layout of FWD

FWD• A few disadvantages are:

i. The whole arrangement over front wheels is complicated.

ii. Constant velocity joints have to be used instead of universal joints

iii. Decrease of tractive forces when the vehicle is up the grade.

Rear engine RWD• The engine is placed at the rear and the rear

wheels are the driven wheels• Advantages are:

i. Better tractive forces up the gradeii. Front axle construction is simplifiediii. Absence of propeller shaft allows decrease in

chassis height

RWD• The disadvantages are:

i. May lose balance at high speeds.

ii. Complicated linkage is required between the engine, clutch and gearbox.

iii. Rear position of engine, cooling effect is reduced.

Front engine four wheel drive• Vehicles which operate on rough roads and

unexpected road profiles, all the four wheels are the driving wheels

• It has got an extra transfer box, which divides the torque between front and rear wheels.

• Also there is a provision for disengaging the front wheels when not required.

4WD

4WD

Transfer Box in 4WD

4WD• The main advantage of the 4WD is that when

any wheels fall into a ditch or a hole, they can be driven out with the help of other wheels or power being delivered to the same wheel

• But this advantage can only at the cost of extra fuel consumption.

ClassificationAutomobiles can be classified in different in

ways according to:-1.Use

i. Mopedsii. Motor cycles, scootersiii. Cars, jeepsiv. Buses and trucks

Classifications2. Capacity

i. Heavy transportii. Light weight transport

3. Make and modeli. Honda, Bajaj, TVS, etc.ii. Maruti Suzuki, Tata, Mahindra etc.iii. BMW, Audi, Ford, Mitsubishi etc.

Classifications4. Fuel Used

i. Petrol vehiclesii. Diesel vehicles

5. Body stylei. Closed cars e.g., sedan, coupe etc.ii. Open cars e.g., convertibleiii. Special styles e.g., estate cars, station wagons etc.

Classifications6. Transmission

i. Manual

ii. Semi-automatic

iii. Fully-automatic

iv. Continuously variable transmission

v. Automated manual

Car Body StylesI. Closed cars:

a. Sedan – has two or four doors, single compartment with two rows of seats.

b. Hatchback – A sedan with a door at the back

c. Coupe – only one row of seats for two persons. Only two doors are provided.

Different Closed Cars

Honda Sedan

Different Closed Cars

Suzuki SX4

Different Closed Cars

Ford Fiesta 5 door hatchback

Different Closed Cars

Honda Civic Hatchback

Different Closed Cars

Honda Genesis Coupe

Different Closed Cars

Honda Accord Coupe

Different Closed Cars

BMW X Coupe

Car Body StylesII. Open cars

a) Sports – Has two doors or less, provided with a collapsible hood, a fold-flat windscreen and removable side-screen.

b) Convertible – Roof in this is of folding type. So the car roof can be closed or opened.

Different Open Cars

Peugeot 9009 Sports Car

Different Open Cars

Dodge Viper Sports Car

Different Open Cars

Audi Sports Car

Different Open Cars

Ford Mustang Convertible

Different Open Cars

BMW M3 Convertible

Different Open Cars

BMW M6 Convertible

Different Open Cars

Chevrolet Camaro Convertible

Car Body StylesIII. Special styles

a) Estate car – A sedan with the passenger roof extended up to rear end. Rear seats are usually collapsible for loading.

b) Station wagon – Rear doors and four or five person seating capacity.

Special Style Cars

Mercedes AMG Estate

Audi RS 6 Estate Car

Special Style Cars

Special Style Cars

Renault Clio Estate

Ford Mustang Station Wagon

Special Style Cars

Special Style Cars

Station Wagon

Special Style Cars

Station Wagon

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