EXPERIMENT No: 1
STUDY OF CHASSIS AND BODY (DIFFERENT TYPES).
AIM: To study about the automobile classis, frame and body.
LEARNING OBJECTIVES:
To understand the basic concepts of automobile chassis.
To understand the functions of an automobile frame.
To understand the construction of an automobile frame.
To understand the basics of the body of an automobile.
THEORY:
AUTOMOBILE CHASSIS
A vehicle without body is called a chassis. It is the backbone of the vehicle. All
moving parts of the vehicle are fitted to it. It is made of steel. To give it extra strength,
it is provided with bolted, riveted or welded cross- pieces. The chassis in general is a
equipped with a I – beam construction front axles. For a god chassis design and for
its good performance it must have fast pick up, strength, safety, durability,
dependability, ease of control, quietness, speed, economy of operation, low centre of
gravity, stability, load clearance, braking ability, simplicity of lubrication, etc. the
chassis frame and front and rear suspension systems without abnormally raising the
frame or transmitting shock to the frame due to road irregularities.
The components of the vehicle like Power plant, Transmission System, Axles,
Wheels and Tyres, Suspension, Controlling Systems like Braking, Steering etc., and
also electrical system parts are mounted on the Chassis frame. It is the main mounting
for all the components including the body. So it is also called as Carrying Unit.
The following main components of the Chassis are
1. Frame: it is made up of long two members called side members riveted
together with the help of number of cross members.
2. Engine or Power plant: It provides the source of power
3. Clutch: It connects and disconnects the power from the engine fly wheel to
the transmission system.
4. Gear Box
5. U Joint
6. Propeller Shaft
7. Differential
Fig.1 Layout of Chassis and its main Components
Types of chassis
Classification of Chassis with respect to its controls
1. Conventional control chassis
2. Semi-forward control chassis
3. Full forward control chassis
Classification of Chassis with respect to engine fitting
1. Engine at front
2. Bus chassis
3. Engine fitted at back
4. Engine fitted in front but cross wise
5. Semi-forward chassis
6. Engine fitted at the centre of the chassis
Figure 2 Photo of an automobile chassis and body.
AUTOMOBILE FRAME
The frames in auto vehicle having independent front-wheel suspension are
heavier in front than those having conventional (or rigid axle) suspension. It is
because there is no rigid front axle in independent front- wheel suspension
vehicles. The side members of the frame are generally made of steel pressings of
channel section. The members have variable depth so that the beam may be made
of uniform strength. The cross- members are generally riveted or welded to the side
members and the longitudinal members.
TYPES OF CHASSIS FRAMES:
There are three types of frames
1. Conventional frame
2. Integral frame
3. Semi-integral frame
1. Conventional frame: It has two long side members and 5 to 6 cross members joined
together with the help of rivets and bolts. The frame sections are used generally.
a. Channel Section - Good resistance to bending
b. Tabular Section - Good resistance to Torsion
c. Box Section - Good resistance to both bending and
Torsion
2. Integral Frame: This frame is used now a days in most of the cars. There is no
frame and all the assembly units are attached to the body. All the functions of the
frame carried out by the body itself. Due to elimination of long frame it is cheaper
and due to less weight most economical also. Only disadvantage is repairing is
difficult.
3. Semi - Integral Frame: In some vehicles half frame is fixed in the front end on which
engine gear box and front suspension is mounted. It has the advantage when the vehicle
is met with accident the front frame can be taken easily to replace the damaged chassis
frame. This type of frame is used in FIAT cars and some of the European and American
cars.
VARIOUS LOADS ACTING ON THE FRAME:
Various loads acting on the frame are
1. Short duration Load - While crossing a broken patch.
2. Momentary duration Load - While taking a curve.
3. Impact Loads - Due to the collision of the vehicle.
4. Inertia Load - While applying brakes.
5. Static Loads - Loads due to chassis parts.
6. Over Loads - Beyond Design capacity.
Functions of Frame
1. To support the load of body, engine, gearbox and radiator.
2. To provide the connecting link for front and rear axles.
3. To carry load of the passengers or goods carried in the body.
4. To withstand stresses caused due to bad road conditions.
5. To withstand forces caused due to a sudden braking or acceleration.
6. To withstand load / force caused due to turning of vehicle.
Figure 3 Components of a typical frame design
AUTOMOBILE BODY
The body is a superstructure of the vehicle. The chassis and the body make the complete
vehicle. In larger and heavier vehicles, the chassis and the body are each made as a
separate unit and then bolted together. The body is usually made from a large number
of steel pressings which are welded together. The body is bolted to the chassis at
numerous points. The rubber or felt-strips being interposed to damp-down (reduce) the
vibrations and noise.
The Automobile bodies are divided in two groups
Body
Passenger Body Commercial body
REQUIREMENTS OF BODIES FOR VARIOUS TYPES OF VECHILE:
The body of the most vehicle should fulfill the following requirements:
1. The body should be light.
2. It should have minimum number of components.
3. It should provide sufficient space for passengers and luggage.
4. It should withstand vibrations while in motion.
5. It should offer minimum resistance to air.
6. It should be cheap and easy in manufacturing.
7. It should be attractive in shape and colour.
8. It should have uniformly distributed load.
9. It should have long fatigue life
10. It should provide good vision and ventilation.
