2. Components of an Automobile
• The basic structure
• The power unit
• The transmission system
• The auxiliaries
• The controls
• The superstructure
3. 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
4. 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.
5. Frameless - Advantages
• Reduced weight and consequent saving in fuel
consumption
• Lower manufacturing costs
• Safety to passengers
• Increased stability of the automobile
6. 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
7. 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
9. 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
11. 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
12. Axles
• There are three different types live rear axles
a) Fully floating type
b) Three quarter floating type
c) Semi-floating type
13. 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
14. 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
15. The Transmission System
• The transmission system consists of a
– Clutch,
– Gear box,
– Propeller shaft, and
– Differential
17. 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
18. 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
19. 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
20. 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
21. Different types of arrangements
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
22. 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.
25. 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.
26. 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 grade
ii. Front axle construction is simplified
iii. Absence of propeller shaft allows decrease in
chassis height
27. 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.
28. 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.
31. 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.
32. Classification
Automobiles can be classified in different in
ways according to:-
1.Use
i. Mopeds
ii. Motor cycles, scooters
iii. Cars, jeeps
iv. Buses and trucks
33. Classifications
2. Capacity
i. Heavy transport
ii. Light weight transport
2. Make and model
i. Honda, Bajaj, TVS, etc.
ii. Maruti Suzuki, Tata, Mahindra etc.
iii. BMW, Audi, Ford, Mitsubishi etc.
34. Classifications
4. Fuel Used
i. Petrol vehicles
ii. Diesel vehicles
4. Body style
i. Closed cars e.g., sedan, coupe etc.
ii. Open cars e.g., convertible
iii. Special styles e.g., estate cars, station wagons etc.
35. Classifications
6. Transmission
i. Manual
ii. Semi-automatic
iii. Fully-automatic
iv. Continuously variable transmission
v. Automated manual
36. Car Body Styles
I. 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.
44. Car Body Styles
II. 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.
52. Car Body Styles
III. 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.
