2. Automobile Engineering
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.
3. Types of chassis
1. Conventional chassis or frame-full chassis
In this type of chassis the body is made as a
separate unit and then joined with ladder
frame. It supports all the systems in a vehicle
such as the Engine, Transmission system,
Steering system, Suspension system.
Advantage
Higher load capacity and strength
Disadvantage
The body tends to vibrate easily and the overall
vehicle handling and refinement is lower.
It is used in truck, bus and in SUV cars and
bigger vehicles.
For chassis 1.1.2 Frame
4. Contd….
2. Non conventional or
frameless chassis
In this type of chassis the ladder frame is absent
and the body itself act as the frame. It supports all
the systems in a vehicle such as the Engine,
Transmission system, Steering system, Suspension
system.
Advantage
Less rattles and squeaks (noise because of loose
parts) are developed.
Handling is better due to the higher body rigidity
and weight.
Disadvantage
The load carrying capacity is lower.
It is not safe in accidental condition.
5. History
The first car ran on India’s roads in 1897.
Until the 1930s, cars were imported directly, but in very
small numbers.
11. 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.
12. Wheels
(a) Two wheeler vehicle, for example : Scooter,
motorcycle, scooty, etc.
(b) Three wheeler vehicle, for example : Auto rickshaw,
three wheeler scooter for handicaps 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.
13. Fuel Used
(a) Petrol vehicle, e.g. motorcycle, scooter, cars, etc.
(b) Diesel vehicle, e.g. trucks, buses, etc.
(c) Electric vehicle which use battery to drive.
(d) Steam vehicle, e.g. an engine which uses steam
engine. These engines are now obsolete.
(e) Gas vehicle, e.g. LPG and CNG vehicles, where LPG is
liquefied petroleum gas and CNG is compressed natural
gas.
14. On the basis of body, the vehicles are classified as :
(a) Sedan with two doors
(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.
15. Transmission
(a) Automatic transmission vehicles: Automobiles that
are capable of changing gear ratios automatically as
they move. e.g: Automatic Transmission Car.
(b) Semi-automatic transmission vehicles: Vehicles that
facilitate manual gear changing with a clutch pedal.
16. Position of Engine
(a) Engine in Front Most of the vehicles have engine in
the front. Example : most of the cars, buses, trucks in
India.
(b) Engine in the Rear Side Very few vehicles have
engine located in the rear. Example : Nano car.
17. Based on Suspension system used:
(a) Convectional – Leaf Spring
(b) Independent – Coil spring, Torsion bar, Pneumatic.
18. Vehicle
Type
Body Style Power Train Suspension
Passenger Car 2D/3D/4D/5D UniBody Engine: 1.0-3.0L
Trans: 5spd/Auto
Driveline: FWD
Front: McPherson
Rear: Multi-link
MPV 4D/5D UniBody Engine: > 2.0L
Trans: Auto
Driveline: FWD
Front: McPherson
Rear: Multi-link
SUV 5D Unibody or Body on
Frame
Engine: 1.8-5.0 L
Trans: Auto
Driveline:
FWD/RWD/AWD
Front: McPherson/SLA
Rear: Multi-link/Solid Axle
Luxury Car 4D Unibody or Body on
Frame
Engine: >2.5 L
Trans: Auto
Driveline: FWD/RWD
Front: SLA (Short long
arms suspension)
Rear: Multi-link
Sports Car 2D/3D Unibody Engine: >3.5 L
Trans: 5Spd
Driveline: RWD
Front: McPherson
Rear: Multi-link
Pickup Truck 2D/4D Body on Frame Engine: >2.5 L
Trans: Auto
Driveline: RWD/AWD
Front: SLA
Rear: Solid Axle
Commercial
Truck
2D Body on Frame Engine: >5 L
Trans: Auto
Driveline: RWD
Front: SLA
Rear: Solid Axle
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22. Classification of Cars based on body Shape:
ONE BOX (VAN/MPV) – It means Engine area, Passenger
area & luggage area all in one box. There wont be separate
compartment. For eg. Omni, Ace Magic, Versa
TWO BOX (HATCHBACK) – It means Engine are has a
separate cabin while Passenger area and luggage area are
together. For eg. M800, Alto, Santro, i10, i20, A-star, Swift
etc.
23.
24. Classification of Cars based on body Shape:
THREE BOX (SEDAN/SALOON/NOTCHBACK) – It
means Engine area, Passenger area & luggage area all are
having different cabin. For eg. SX4, City, Fiesta, Dzire.
ESTATE/STATION WAGON - Its nothing but sedan whose
roof is extended till the rear to create more boot space. For
eg. Indigo Marina, Octavia Combi, etc.
26. Classification of Cars based on body Shape:
SUV (Sports Utility Vehicle) – These vehicles have large
tyres, higher seating, higher ground clearance. The engine
area is separate, but the passenger & luggage area are
enclosed together. Most of these vehicles are equipped with
either 4 wheel drive system or has the option for that. For
eg. CRV, SAFARI, GRAND VITARA, PAJERO etc.
http://www.indiamarks.com/car-segmentation-society-
indian-automobile-manufacturers/#
29. Functions of major components of
an Automobile
Chassis and Frame
The chassis is formed by the frame with the frame side
members and cross members. The frame is usually made
of box, tubular and channel members that are welded or
riveted together. In addition to this, it comprises of the
springs with the axles and wheels, the steering system
and the brakes, the fuel tank, the exhaust system, the
radiator, the battery and other accessories. Along with
this the frame supports the body.
30. Engine or Power Plant
The engine is the power plant of the vehicle. In general,
internal combustion engine with petrol or diesel fuel is
used to run a vehicle. An engine may be either a two-
stroke engine or a four-stroke engine. An engine consists
of a cylinder, piston, valves, valve operating mechanism,
carburetor (or MPFI in modern cars), fan, fuel feed
pump and oil pump, etc. Besides this, an engine requires
ignition system for burning fuel in the engine cylinder.
31. Transmission System (Clutch and Gear Box)
The power developed by the engine is transferred to the
wheels by transmission system. Transmission system
must do three jobs :
(a) It must provide varying gear ratios. Number of gear
ratio are equal to number of gears in a vehicle.
(b) It must provide a reverse gear for moving vehicle in
reverse direction.
(c) It must provide a neutral or disconnecting
arrangement so that the engine can be uncoupled
from the wheels of the vehicle. In a conventional
transmission system, there is a clutch, a manually
operated transmission (gear box), a propeller shaft
and a differential or final drive
32. Clutch
The purpose of the clutch is to allow the driver to couple
or decouple the engine and transmission. When clutch is
in engaged position, the engine power flows to the
transmission through it (clutch). When gears are to be
changed while vehicle is running, the clutch permits
temporary decoupling of engine and wheels so that gears
can be shifted.
33. Final Drive
Final drive is the last stage in transferring power from
engine to wheels. It reduces the speed of the propeller
shaft (drive shaft) to that of wheels. It also turns the
drive of the propeller shaft by an angle of 90° to drive the
wheels. The propeller shaft has a small bevel pinion
which meshes with crown wheel. The crown wheel gives
rotary motion to rear axles. The size of crown wheel in
bigger than that of bevel pinion, therefore, the speed of
rear axles (or crown wheel) in lower than the speed of
pinion. Final drive is of two types, i.e. chain type and
gear type.
34. Braking System
Brakes are used to slow down or stop the vehicle.
Hydraulic brakes are generally used in automobiles,
where brakes are applied by pressure on a fluid.
Mechanical brakes are also used in some vehicles. These
brakes are operated by means of leavers, linkages,
pedals, cams, etc. Hand brake or parking brake is known
usually mechanical brake. These are used for parking the
vehicles on sloppy surfaces and also in case of
emergency.
35. Gear Box :
Gear box contain gearing arrangement to get different
speeds. Gears are used to get more than one speed ratios.
When both mating gears have same number of teeth,
both will rotate at same number speed. But when one
gear has less teeth than other, the gear with less number
of teeth will rotate faster than larger gear. In a typical car,
there may be six gears including one reverse gear. First
gear gives low speed but high torque. Higher gears give
progressively increasing speeds. Gears are engaged and
disengaged by a shift lever.
36. Steering System :
It is mechanically linked to the wheels to provide the
steering control. The primary function of the steering
system is to provide angular motion to front wheels so
that vehicle can negotiate a turn. It also provides
directional stability to vehicle when the vehicle moves
ahead in straight line. Now-a-days, many vehicles are
equipped with power steering which uses pressure of a
fluid to reduce steering effort. When driver turns the
steering wheel, a hydraulic mechanism comes into play
to provide most of the effort needed to turn the wheel.
37. Front Axle
A part of the weight of vehicle is transmitted to the
wheels through this axle. The front axle performs
several functions.
It carries the weight of the front of the vehicle and also
takes horizontal and vertical loads when vehicle moves
on bumpy roads. When brakes are provided on front
wheels, it endures bending stresses and torsional
stresses. It is generally made from steel drop forging. It
is robust in construction.
38. Suspension System
Suspension system of an automobile separates the wheel
and axle assembly of the automobile from its body. Main
function of the suspension system is to isolate the body
of the vehicle from shocks and vibrations generated due
to irregularities on the surface of roads. Shock absorbers
are provided in the vehicles for this purpose. It is in the
form of spring and damper. The suspension system is
provided both on front end and rear end of the vehicle.
A suspension system also maintains the stability of the
vehicle in pitching or rolling when vehicle is in motion.
39. Front wheel drive and Rear wheel drive
Various differences between Front wheel drive and Rear wheel drive car are as
follows:
In FWD the clutch, gearbox and differential are made as of one unit and are
called transaxle where in RWD the clutch and gearbox is at front whereas
the differential is at the rear driven by propeller shaft.
In FWD the weight on front wheel is more compared to that in RWD.
FWD configuration provides low floor since there is no longer propeller
shaft as compared to RWD.
In FWD there is more luggage space at back when compared to RWD due
to presence of differential at front.
Due to more weight on front wheel in FWD the vehicle has more adhesion
on road when compared to RWD.
In FWD, on gradient or while accelerating the weight shifts to rear wheel
which is not desirable hence tractive effort is reduced.
Due to more weight on front wheel in FWD the steering is hard and there is
always understeer.
40. Rear-Wheel Drive
Pros (Advantages):
During dry conditions, rear-wheel drive improves handling due to “load transfer” in acceleration and
more even weight distribution.
Rear-wheel drive tends to have less costly maintenance since there aren’t as many parts packed into a
small space. Front-wheel drive repairs and maintenance may cost more since they have to remove
more parts for workable access.
You won’t experience “torque steer,” the tendency that FWD vehicles have to veer to the right or left
during acceleration.
Towing large loads is easier since the wheels doing the pulling are located closer to the load. Also,
steering is much easier since the back wheels are providing the power while the front wheels do the
work of steering.
While drifting is not recommended for most drivers, it is easier to drift with RWD than FWD or
4WD/AWD.
41. Rear-Wheel Drive
Cons (Disadvantages):
Rear-wheel drive may be more fun to drive, but it also makes it more
difficult to master. With modern stability and traction controls, however,
the driving differences of RWD don’t present a problem for most drivers.
There is less interior space due to more room needed for the transmission
tunnel and driveshaft.
There may be less trunk room since more equipment must be placed
underneath the trunk.
The driveshaft, which connects the front engine to the back axle, adds more
weight. RWD weighs slightly more than FWD, but less than 4WD and
AWD.
Additional materials translate to a slightly higher purchase price.
Since RWD pushes the car rather than pulls it, it has more difficulty
maneuvering in wet and snowy conditions. With modern technology, such
as stability and traction control, however, this disadvantage is greatly
reduced.
42. Front-Wheel Drive
Pros (Advantages):
The engine and transmission are located directly above the front wheels, which
can provide better traction when climbing hills and driving on slippery roads.
Since all the equipment is up front, they create more space and leg room in the
back.
Front-wheel drive has less components than any other drivetrain setup, making
the vehicle lighter and improving its gasoline mileage. That’s why most
economy-type cars are front-wheel drive.
There is greater tactile feedback through the steering wheel if the wheels are
slipping.
Front-wheel drive is a simpler system and tends to be less expensive to buy and
maintain.
If most of your driving is in dry or rainy conditions, a front-wheel drive system
is all you need. Most modern front-wheel drive systems contain anti-lock
braking (ABS) and traction control, making them perfectly suitable for light
snow conditions as well.
43. Front-Wheel Drive
Cons (Disadvantages):
Since all the weight is located in the front of the vehicle, front-
wheel drive cars tend to understeer.
During sudden acceleration, front-wheel drive vehicles tend to
veer to the right or left because of something called “torque
steer.”
Front-wheel drive tends to have a lower towing capacity than
rear-wheel or 4WD/AWD drivetrains.
Front-wheel drive has worse acceleration than rear-wheel drive,
which is why most sporty and race cars use rear-wheel drive.
With all the weight up front, front-wheel drive can make
handling more difficult.
CV joints/boots in FWD vehicles tend to wear out sooner than
rear-wheel drive vehicles.
