2. Course Objectives
• Understand the basic structure of an automobile
• Understand construction of suspension system
• Understand transmission system and its elements
• Understand braking system, steering system and electrical system
3. Syllabus
UNIT-I
Vehicle structure: Type of automotive vehicles, general layout, vehicle
construction-chassis, frame and body, types of frames, frameless and unitary
construction, position of power unit.
Suspension system: Objects & principles of suspension system, types, rigid axle
suspension & Independent suspension for front & rear ends, simple & double arm
parallel & perpendicular type of suspension system. Gas filled suspension system.
Springs- Purpose, types viz. leaf, coiled, rubber, air, suspension system, torsion bar,
stabilizer, telescopic damper.
4. UNIT–II
Clutches: Characteristics, functions, principles of operation of clutch, friction
clutch, single-plate, multi-plate, centrifugal clutch, positive clutch, friction plate
clutch lining materials. Torque transmitted and related problems.
Fluid fly wheel : Construction, working principles & characteristics.
UNIT–III
Gear Box- Object of Gear Box, air, rolling & gradient resistance, tractive effort variation with
speed, performance curve.
Types of Gear Boxes - Sliding mesh, constant mesh, synchromesh device, automatic
transmission, overdrive, lubrication of gear box.
Torque Converter - Principles of working, characteristics, Torque converter with direct drive.
Testing of Automobiles
5. UNIT–IV
Universal Joint - Types, propeller shaft, slip joint.
Differential – Functions, single & double reduction differential, limited slip
differential.
Front Axle - Live & dead axle, stub axle.
Back Axle – Hotchkiss drive, torque tube drive.
Tyres -Types specification, causes of tyre wear & rim.
Brakes & Braking system - Purpose, principles, layout of braking system.
Classification, mechanical, hydraulic, master cylinder, Tandem master cylinder,
wheel cylinder, self energizing & self adjusting brakes, disc brakes, antiskid brakes,
power operated brakes.
6. UNIT–V
Steering system:- Gear links, types of steering gears, reversibility of steering, center point steering, steering
geometry viz. castor, camber, king pin inclination toe in, toe out, cornering power, under-over steer; power
steering, effect of shimmy, condition of true rolling, calculation of turning radius. Correct steering equation
and related problems.
Electrical System: Battery: construction, maintenance, testing and charging. Cut-out, lighting circuit, horn,
signals etc.
TEXTBOOKS
1.Automobile Engineering – Kripal Singh – Standard Publications, New Delhi
2.AutomobileMechanics- N. K. Giri – Khanna Publishers, New Delhi
REFERENCE BOOKS
1.Automobile Engineering – G. B. S. Narang – Khanna Publishers, New Delhi
2.Automotive Mechanics: Principles and Practices -W. H. Crouse, and D. L. Anglin, TMH
3.Automobile Engineering – K. R. Govindan – Anuradha Agencies
4.The Automobile - Harbans, Reyat Singh - S. Chand, NewDelhi
5.Automotive Mechanics – Joseph Heitner – CBS Pub., New Delhi
6.Motor Vehicle – Newton & Steeds–Life & Sons Limited.
7. Course Outcome
• Graduates will gain a strong foundation in core automobile
engineering, both in theoretical and applied concepts.
• Acquire knowledge and hands-on competence in the design and
development of automobile.
• Graduates will demonstrate the ability to identify and solve
automobile engineering maintenance problems.
8. “Automobile engineering is a branch of engineering which deals with
everything about automobiles and practices to propel them.”
Automobile is a vehicle driven by an internal combustion engine and it
is used for transportation of passengers and goods on the ground.
Automobile can also be defined as a vehicle which can move by itself.
Examples : Car, jeep, bus, truck, scooter, etc.
9. Classification of Vehicles
• On the Basis of Load :
(a) Heavy transport vehicle (HTV) or heavy motor vehicle (HMV),
e.g. trucks, buses, etc.
(b) Light transport vehicle (LTV)
e.g. pickup, station wagon, etc.
(c) Light motor vehicle (LMV),
e.g. cars, jeeps, etc.
10. Cont..
• On the Basis of Wheels :
(a) Two wheeler vehicle, for example : Scooter, motorcycle, scooty, etc.
(b)Three wheeler vehicle, for example : Auto rickshaw, three wheeler scooter and
tempo, etc.
(c) Four wheeler vehicle, for example : Car, jeep, trucks, buses, etc.
(d) Six wheeler vehicle, for example : Big trucks with two gear axles each having
four wheels
11. Cont..
On the Basis of Fuel Used
(a) Petrol vehicle,
e.g. motorcycle, scooter, cars, etc.
(b) Diesel vehicle,
e.g. trucks, buses, etc.
(c) Electric vehicle,
e.g. battery drive
(d) Steam vehicle,
e.g. an engine which uses steam.
(e) Gas vehicle,
e.g. LPG and CNG vehicles, where LPG is liquefied petroleum gas and
CNG is compressed natural gas.
12. Cont..
• On the Basis of Body
(a) Sedan with two door
(b) Sedan with four doors
(c) Station wagon
(d) Convertible, e.g. jeep, etc.
(e) Van
(f) Special purpose vehicle,
e.g. ambulance, milk van, etc.
13. Sedan
Uses center body pillars, or “B” pillars,
between the front and rear doors. A
hardtop does not use “B” pillars.
19. Cont..
• Transmission
(a) Conventional vehicles with manual transmission, e.g. car with 5 gears.
(b) Semi-automatic
(c) Automatic : In automatic transmission, gears are not required to be
changed manually. It is automatically changes as per speed of the
automobile.
• Position of Engine
Engine in Front :
Most of the vehicles have engine in the front.
Example : most of the cars, buses, trucks in India.
Engine in the Rear Side:
Very few vehicles have engine located in the rear.
Example : Nano car.
20. Components of an automobile
Main units of an automobile are:
1. The basic structure
2. The power plant
3. The transmission system
4. The auxiliaries
5. The controls
6. The superstructure
22. Chassis
Consists of the vehicle’s frame and everything
attached to it except the body
Includes the tyres, wheels, engine, transmission,
drive axle assembly, and frame
23. Chassis
Chassis of an automobile consists of following components:
Engine and Radiator
Transmission System (includes clutch, gear box, propeller shaft and
rear axle)
Suspension System
Road wheels
Brakes
Fuel Tank
25. Components of the vehicle can be mounted in two ways:
i) Conventional Construction
Separate frame is used. This type of construction is being used
presently only for heavy vehicles.
ii) Frameless or unitary construction
No separate frame is employed. The body structure is so designed
as to combine the function of body and frame. Example: closed cars
28. Advantages and disadvantages of unitized chassis over conventional chassis
Advantages:
Reduce weight hence saving fuel
Low manufacturing cost
During collision, the body crumbles thus absorbing more shock
Lower body position may be obtained thus resulting in increased stability
Disadvantages:
Reduction in strength and durability
Economical only if frameless chassis is adopted in mass production
Increased cost of repairs in case of damage to the body
Topless cars are difficult to design
29. Chassis are classified as:
i) Conventional control chassis – Engine is mounted in front of drivers
cabin.
ii) Semi-forward control chassis – Engine is so mounted such that half
of it is in the driver’s cabin whereas other half is in front, outside the
drive’s cabin.
iii) Full-forward control chassis – Engine is mounted completely inside
the driver’s cabin.
30.
31.
32.
33. FRAME
A frame is the main structure of the chassis of a motor vehicle. All other
components fasten to it.
34. Requirements of Frames
• Support the weight of the vehicle and everything inside it including
passenger and cargo.
• Provide the frame for the suspension, engine and drivetrain to be
mounted.
• It must be strong to hold these components in place during various
driving conditions.
• Handles or resist any torsional stress (such as bending or twisting of
the body) that the vehicle may be subjected to as it drives.
• It allows the vehicle to pull objects as these heavy objects must be
directly or indirectly attached to the chassis.
35. Type of load Effect on frame
Weight of vehicle and passenger Bending of side members
Vertical load when vehicle posses across
bump or hollow
Longitudinal torsion (one wheel up while
other is down)
Load due to cornering force during turns Lateral bending of side members
Load due to wheel impact with road obstacle Distortion of frame to parallelogram shape
Engine torque and breaking torque Bending of side members in vertical plane
Impact load during collision General collapse
36. Construction of frame
The frames are made of the following steel sections:
i) Channel section
ii) Box section
iii) Tubular section
• Channel section is used in long members of the frame.
• Box section is used in short members of the frame.
• Tubular section is used these days in three-wheelers, scooters and matadors, pick-ups
frames.
-The channel section is good in bending, tubular in torsion and box in bending and
torsion.
38. 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. Tubular Section – Good resistance to torsion
c. Box Section – Good resistance to both bending and torsion
40. 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.
42. 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.
43.
44. TYPES OF FRAMES
1. Ladder Frame
2. Backbone Frame
3. X-frame
4. Perimeter Frame
5. Platform Frame
6. Unibody (or) Unit body
7. Sub Frame
45. LADDER FRAME
• The ladder frame is the simplest and oldest of all designs.
• It consists of two symmetrical rails, or beams, and cross member connecting them.
• Originally seen on almost all vehicles, the ladder frame was gradually phased out on cars
around the 1940s and is now seen mainly on trucks.
• This design offers good beam resistance because of its continuous rails from front to rear,
but poor resistance to torsion.
• Also, the vehicle's overall height will be higher due to the floor pan sitting above the
frame instead of inside it.
46.
47. BACKBONE FRAME
• Backbone frame is a type of an automobile construction frame that is
similar to the body-on-frame design.
• Instead of a two-dimensional ladder type structure, it consists of a
strong tubular back bone (usually rectangular in cross section) that
connects the front and rear suspension attachment areas.
• A body is then placed on this structure.
48.
49. X-FRAME
• This is the design used for the full-size American models of General
Motors.
• In which the rails from alongside the engine seemed to cross in the
passenger compartment, each continuing to the opposite end of the cross
member at the extreme rear of the vehicle.
• It was specifically chosen to decrease the overall height of the vehicles, and
to increase in the space for transmission.
• The X-frame was claimed to improve on previous designs, but it lacked side
rails and thus did not provide adequate side-impact and collision protection.
• So, this design was replaced by perimeter frames.
50.
51. PERIMETER FRAME
• Similar to a ladder frame, but the middle sections of the frame rails sit
outboard of the front and rear rails.
• This was done to allow for a lower floor pan, and therefore lower overall
vehicle in passenger cars.
• In addition, the perimeter frame allows lower seating positions when that is
desirable, and offers better safety in the event of a side impact.
• However, the design lacks stiffness, because the transition areas from front
to center and center to rear reduce beam and torsional resistance.
52.
53. PLATFORM FRAME
• This is a modification of the perimeter frame in which the passenger
compartment floor and often the luggage compartment floor were
permanently attached to the frame, for extra strength.
• Neither floor pieces were sheet metal straight off the roll, but had been
stamped with ridges and hollows for extra strength.
• This was used by the Germans on the Volkswagen Beetle and the
Mercedes-Benz "Ponton" cars of the 1950s and 1960s, where it was
called in English-language advertisements as the "frame floor".
54.
55. UNI-BODY
• In an unibody (also unit body, unitary construction, or unitized
construction) design, the frame and body are constructed as a single
unit.
• This became the preferred construction for mass market automobiles
and crossovers especially in the wake of the two energy crises of the
1970s and the mid-2000s oil price increases.
56.
57. SUB FRAME
• A subframe is a structural component of a vehicle.
• Such as an automobile or an aircraft, that uses a separate structure within a larger
body-on-frame or unit body to carry certain components, such as the engine,
drivetrain, or suspension.
• The sub frame is bolted and/or welded to the vehicle.
• When bolted, it is sometimes equipped with rubber bushings or springs to dampen
vibration.
• The principal purposes of using a subframe are, to spread high chassis
loads over a wide area of relatively thin sheet metal of a monocoque body
shell, and to isolate vibration and harshness from the rest of the body.
• For example, in an automobile with its power train contained in a subframe,
forces generated by the engine and transmission can be damped enough
that they will not disturb passengers.
• As a natural development from a car with a full chassis, separate front and
rear subframes are used in modern vehicles to reduce the overall weight
and cost.
