ae chassis and automobile classification-converted.pptx

UNIT 1
VEHICLE STRUCTURE AND
ENGINES

AUTOMOBILE INTRODUCTION
• The word automobile comes, via the
French automobile from the Ancient Greek
word α τός
ὐ (autós, "self") and
the Latin mobilis ("movable"); meaning a vehicle
that moves itself.

Requirements of an
Automobile
The following requirements must be fullfilled for an
automobiles.
1. It should develop power by itself.
2. The rate of power development must be easily
controlled.
3. There should be an arrangement to transmit the
power developed to the wheels.
4.It should be possible to control or vary the torque.
5.It must have directional control.
6. An arrangement was needed to stop the vehicle while it
is running.

ENGINE AUXILIARY SYSTEMS
 Injection system
 Ignition system
 Turbocharger
 Catalytic convertor
Electronically controlled gasoline injection system for SI engines,
Electronically controlled diesel injection system (Unit injector
system Rotary distributor type and common rail direct injection
system).
Electronic ignition system (Transistorized coil ignition system,
capacitive
discharge ignition system).
Turbo chargers (WGT, VGT).
Engine emission control by three way catalytic converter system,
Emission norms (Euro and BS).

TRANSMISSION SYSTEMS
 Clutch-types and construction.
 Gear boxes- manual and automatic, gear shift mechanisms, Over
drive, transfer box, fluid flywheel, torque converter, propeller
shaft, slip joints, universal joints.
 Differential and rear axle.
 Hotchkiss Drive and Torque Tube Drive

STEERING, BRAKES AND SUSPENSION SYSTEMS
 Steering geometry and types of steering gear box-Power
Steering.
 Types of Front Axle, Types of Suspension Systems,
 Pneumatic and Hydraulic Braking Systems, Antilock Braking
System (ABS).
 Electronic brake force distribution (EBD) and Traction Control.

ALTERNATIVE ENERGY SOURCES
Use of Natural Gas, Liquefied Petroleum Gas.
Bio-diesel, Bio-ethanol, Gasohol
Hydrogen in Automobiles- Engine modifications required –
Performance, Combustion and Emission Characteristics of SI and
CI engines with these alternate fuels.
Electric and Hybrid Vehicles.
Fuel Cell Note: Practical Training in dismantling and assembling
of Engine parts and Transmission Systems should be given to
the students.

Types of
Automobiles
• Automobiles can be classified with respect to different
purposes which are as follows:
• (i) With respect to the purpose:
(a) passenger vehicles, Examples: Car, Bus, Jeep, Scooter,
Mopeds, Motor cycle.
(b) Goods carriers. Examples: Trucks, Lorries.
(ii) With respect to the fuel used
(a) Petrol vehicle (b) Diesel vehicles (c) Gas vehicles (d)
electric vehicle (e) Solar vehicle.

• (iii) With respect to capacity:
(a)Heavy transport vehicle., Example: Bus, Lorries,
Trucks, Tractors.
(b) Light transport vehicle or light motor vehicles.
Example: Car, Scooter, Mopeds, Motor Cycles,
Jeeps.
(iv) With respect to the number of wheels:
(a) Two wheelers. Examples: Scooters, Motor
cycles,
Mopeds.
(b) Four wheelers. Examples: Car, Jeep, Buses,
Trucks.
(c) Three wheelers .Examples: Auto, Tempos.
(d) Six wheelers. Examples: Heavy trucks.

• (v) With respect to the drive of the
vehicle:
(a) Single wheel drive vehicles.
(b) Two wheel drive vehicles.
(c) Four wheel drive vehicles.
(d) Six wheel drive vehicles.

CHASSIS
• Chassis is a French term and was initially used to denote
the frame or main structure of a vehicle.
• Chassis is nothing but, a vehicle without body

Main components of
chassis
• Frame
• Steering mechanism
• Front suspension
• Radiator
• Engine
• Transmission system
• Wheels
• Propeller shaft
• Differential unit
• Universal joint
• Brakes and braking system
• Fuel tank
• Silencer
• Electrical system
• Rear and front springs
and shock absorber

16 MARKS
1. Explain Front engine front wheel drive and Front engine rear wheel drive
with a sketch.
2. Explain Rear engine Rear wheel drive and All wheel drive layout with a neat
sketch.
3. What are the various types of frame , explain the conventional frame with
a diagram.
4. What are the various types of frame , explain the semi integral and
frameless structure with a diagram.
5. What is the importance of aerodynamics and explain various aerodynamic
forces and moments.
6. Explain the various components of i.c engine with neat sketch.
7. Explain the various components of i.c engines with their functions
and materials used for manufacturing.

Front engine front wheel drive
• The engine was transversely fixed in front of the frame
• Two drive shafts are connected with the differential and
front wheels.
• So the front wheels receive the power from the engine.
• This construction is suitable for the vehicle which has
less wheel base.
• It is widely used in Tata indica , maruthi-800
• Space utilization is less and power loss is less due to
the absence of propeller shaft.
1.Explain Front engine front wheel drive and Front engine rear wheel drive
with a sketch.

ae chassis and automobile classification-converted.pptx

• The center of gravity of the vehicle is typically farther
forward
than a comparable rear-wheel drive layout.
• In front wheel drive cars, the front axle typically supports
around 2/3rd of the weight of the car (quite far off the
"ideal" 50/50 weight distribution). This is a contributing
factor in the tendency of front wheel drive cars to
understeer.
• Rear tire traction is decreased and the car may swap ends
on icy roads easier.

Front Engine Rear Wheel
Drive
• The engine is fixed in front of the frame.
• Better handling in dry conditions.
• Engine power is trasmitted to the rear wheels through the
propeller shaft. So it starts to rotate at first.
• This type of construction provides sufficient pushing force
to the vehicle in order to move it easily.
• Generally it is used in, bus, lorry and ambassador car.

• Disadvantages of RWD are higher assembly and production
costs, more parts.
• Increased weight - The drive shaft, which connects the
engine at the front to the drive axle in the back, adds weight.
• A rear wheel drive car will weight slightly more than a
comparable front wheel drive car, but less than four
wheel drive.
• Higher purchase price - Due to the added cost of
materials,
rear wheel drive is typically slightly more expensive.

Rear Engine Rear Wheel Drive.
• The engine is fixed at the rear end of the frame.
• Initially, the engine drive is given to the wheels.
• As the engine is at the rear, engine heat is not transferred to
the
driver compartment.
• But to operate clutch and gear box, long links are necessary.
This is the major disadvantage.
• It is used in valvo buses and auto.
• Low steering control
• This type of layout needs very lengthy linkages
2. Explain Rear engine Rear wheel drive and All wheel drive layout
with a neat sketch.

Four Wheel
Drive
• The engine is fixed in front of the frame.
• In this, additionally, a transfer case is fixed behind the
gear box.
• Two propeller shafts (P1 and P2) arre connected with two
differentials (D1 and D2) and with the transfer case.
• Due to this, the power is simulataneously transferred to all
the four wheels.
• A shifting lever is fixed on the transfer case to connect
or disconnect the power to the front wheels.

Advantages
• The additional weight of AWD systems encourages more grip.
• While the weight of AWD vehicles improves their handling.
Disadvantages
• The primary disadvantage of an AWD vehicle is its cost.
• AWD systems require more fuel to power the additional
wheels and are less fuel efficient than comparable two-
wheel- drive vehicles.

• The primary disadvantage of an AWD vehicle is its cost.
• AWD systems require more fuel to power the additional
wheels and are less fuel efficient than comparable two-
wheel- drive vehicles.

Types ofFrames
Conventional frame
construction Semi-integral
frame construction Frameless
frame construction
3. What are the various types of frame , explain the conventional
frame with a diagram.

Conventional frame
construction
It is a non-load carrying frame.
Because it transfer the load of the vehicle to the
suspension system.
The total frame is mounted on the wheel axle by
means of spring.
The body of the material is made up of rubber
mountings, (so the body is completely isolated from
frame deflection)
It is mostly used in heavy vehicles like trucks
CHANNEL, TUBULAR, or BOXcross section are
used in this type of frame.

Channel Frame
Tubular Frame
Channel Frame

4.What are the various types of frame , explain the semi integral and
frameless structure with a diagram.
TypesofFrames
Conventional frame
construction Semi-integral
frame construction Frameless
frame construction

Semi
Integral
In this the rubber mountings are replaced by relatively
stiff mountings (thereby transferring a part of the frame
load to body structure also).
Heavy in nature compared to conventional type.
This type is popular in small european and american
cars.

Integral or Frameless
construction
It is a monocoque
construction There is no
separate frame.
In this the longitudinal
member are elimanted.
Cross members are combined with the floor of the body
and welded.
Body gives the mounting for
Engine
Transmission
Suspension
and
Other mechanical units

Integral or Frameless
construction
Due to this, the weight get reduced which is an important
factor in design consideration.
Suitable for mass produced
vehicles. Increased strength
rigidity.
In this stresses are evenly
distributed.

Various Engine Components
 Cylinder
 Cylinder block
 Cylinder head
 Cylinder liners
 Crank shaft
 Piston
 Manifold
 Cam shaft
 Connecting rod
 Valves(inlet and
exhaust)
 Flywheel
5.Explain the various components of i.c engine with neat sketch.

Cylinder
 A cylinder in an I.C engine is the main part in which
combustion takes place.
 The cylinder has to withstand high temperature of 2200°C
and high pressure of 70 bar.
 Cylinder in which the pistons reciprocate back and
forth to develop power.

Cylinder block
 This is the main body of the engine which contains cylinders.
 Piston reciprocates inside the cylinder to develop power
and provides housing for the crank shaft and other engine
parts. This is the basic frame for the engine.
 During combustion, high pressure and temperature will be
developed inside the cylinder.
 Therefore it should be made of material which can resist
high temperature and pressure.

Cylinder Head
 It is attached to the top surface of the cylinder block,
called block deck, by means of studs fixed to the block.
 The gaskets are used to provide a tight leak proof joint
at the
interface of the head and the block.
 The cylinder head forms a combustion chamber above each
cylinder.
 Part that covers and encloses the Cylinder.
 It contains cooling fins or water jackets and the valves.
 Some engines contains the cam shaft in the cylinder head.

Cylinder Liners
 Inside the cylinder, the piston constantly reciprocates which will
cause wear of cylinder.
 When the cylinder diameter increased beyond the limit, we may
discard the entire cylinder block which is costly.
 So a separate liner which is in the form of sleeve is inserted
into the cylinder bore.
 When the wear takes place, the liner alone replaced.

Wet liner:
The liners are
surrounded by cooling water. It
provides wear resisting
surface for the piston to
reciprocate. It also acts as a
seal for the water jackets.
Dry liner:
Dry liners have metal-
to-metal contact with the
cylinder block. They are not
directly in touch with cooling
water.

Functions of Piston
To transmit the force of explosion to the crankshaft.
It provides a sealing effect.(seals high pressure gases)
It should withstand high temperature at high compression
ratios.

Piston
 The top of the piston is called head or crown.
 It has to hold piston rings and oil rings.
 It is opened at the bottom end and closed at the top.
 In Low Performance Engines
 Generally low cost, low performance engines have flat head.
 In such pistons which come close to the valves, the head
is provided with valve relief.

In High Performance Engines
 Pistons used in high power engines may have a raised dome,
which is used to increase the compression ratio.
 In some other engines, the pistons may be specially dished
to form a desired shape of combustion chamber, jointly with
cylinder head.
 In case of a piston containing part of the combustion
chamber in its crown, compression ratio can be controlled
accurately, but the disadvantage is that in this case much larger
amount of heat has to be dissipated through the piston and the
rings.

Piston Rings
Four stroke: Three rings
Top two are compression
rings (sealing the compression
pressure in the cylinder)and
the third is an oil ring (scrapes
excessive oil from the cylinder
walls)
Two Stroke: Two Rings
Both the rings are
Compression rings.

Connecting Rod
It is usually a steel forging of circular, rectangular, I, T, or
H
section.
Its bigger end is connected to the crank by a crank pin
and smaller end is connected to the piston by a gudgeon
pin.
It has a passage for the transfer of lubricating oil.

Crank and Crankshaft
 It converts the reciprocating motion of a piston into
rotary motion.
 Both crank and crankshaft are steel forgings machined to a
smooth finish.
 The crankshaft is the backbone of the engine.
 The power required for any useful purpose is taken from
crankshaft only.

Camshaft
 Turns at 1/2 the speed of the crankshaft
 Must be mechanically coupled to the crankshaft for timing
purposes (gears, belts, chains)
 The camshaft consists of bearing journals and lobes spaced
along the shaft
 Each lobe is positioned to open and close a valve at a
specific time.

6. Explain the Valves and the Valve System with a neat sketch

Valves and the Valve System
Valves control the flow of gases inside the engine
Poppet valves are the most common for opening and closing
during operation.
•Exhaust Valve lets the exhaust gases escape the
combustion
Chamber. (Diameter is smaller than Intake valve).
•Intake Valve lets the air or air fuel mixture to enter the
combustion chamber. (Diameter is larger than the exhaust valve)
Minimum Two Valves per Cylinder.
Valve faces are ground to 30 degrees for intake (airflow) and 45
degrees (cooling) for exhaust.

Manifolds
There are separate sets of pipes attached to the cylinder head
which carry the air-fuel mixture and the exhaust gases. These are
called manifolds.
 Inlet manifold
 Exhaust manifold

Inlet manifold
The inlet manifold carries the air-fuel mixture from the carburetor
to the cylinder.
The shape and size of the inlet manifold must be such as to
prohibit the formation of fuel droplets without restricting the
air flow.
The manifold must be large enough to allow sufficient flow
for maximum power.

Exhaust manifold
It is the passage which carries the exhaust gases from the
exhaust
valve to atmosphere.

Flywheel
The flywheel is heavy and perfectly balanced wheel usually
connected to the rear end of the
crankshaft. Flywheel serves as a energy
reservoir
It stores energy during the power stroke and releases during
other strokes.
It is made up of cast iron or cast steel.

8. Explain the various components of i.c engines with their functions
and materials used for manufacturing

AERODYNAMICS FORCES AND MOMENTS
A simple definition of aerodynamics is the study of the flow of air around and
through a vehicle, primarily if it is in motion.
Importance of Aerodynamics:
 To reduce drag force, achieve maximum speed & acceleration for the same power output.
 If drag force is reduced. Then, fuel consumption of the vehicle can be reduced , to
the max about 35% of fuel cost could be reduced by proper stream lining.
 Good aerodynamic design gives better appearance & styling.
 By reducing the various forces & moments, good stability & safety can be achieved.
 This study helps to provide proper ventilation system.
 Helps to understand the dirt flow & exhaust gas flow patterns.
 With proper aerodynamic design, aerodynamic noise could be reduced, which results
in quite running of the vehicle.
9.What is the importance of aerodynamics and explain various
aerodynamic forces and moments.

Various Forces are
Fx – Forces of Air
drag Fy – Cross wind
force Fz –
Aerodynamic Lift
Mx – Rolling moment caused by the force
Fx about x axis
My – Pitching moment caused by the force Fz about y axis
Mz – Yawing moment caused by the force Fy about z axis
AERODYNAMIC DRAG
Form drag (57%) : Mainly depends upon longitudinal section of the vehicles.
Body shapes that minimize +ve aerodynamic force on the front & minimize –ve
aerodynamic force on the rear
Lift drag (8%) : vortices (created by the aerodynamic lift of the body) formed at

Surface drag (10%) : Friction between the boundary layer and body
surface. The drag of small surface imperfections with the boundary
layer is considered as surface drag. Body smoothness should be of
the order of 0.5 to 1.0 microns. A well polished surface is more
attractive and as well as more economical.
Interference drag (15%) : The flow over many exterior components
interact with the flow over basic body shape leads to interference
drag. Ex : hood ornaments, wind shield wipers, radio aerial, rear
view mirror, no. plates, door handles, rain gutters, roof racks etc and
below
the vehicles such as axles, tow – bar etc.
Cooling & ventilation system drag (10%) : Energy absorbed by the
radiator to have negative drag.

VALVE TIMING (VT) is one of the most important aspects of
consideration in the design of an automobile engine. Simply defined, it
is the timing, or regulation of the opening and closing of the valves. In
simpler terms, it is the way an engine 'breathes'.
VALVE TIMING (VT)
10. Explain the Variable Valve timing with a neat sketch

In an I.C.engine, usually the inlet valves open a few degrees (of crank angle) prior
to TDC, and close after BDC. Similarly, the exhaust valves open a few degrees
before BDC and close a few degrees after TDC. This is done to maximise:
" Intake of air/air-fuel mixture; and
" Scavenging, i.e. the exhaust of burnt gases.
Until recently, most engines around the world utilised ordinary or static
VT, where the parameters of valve opening, lift, and closing (VO, VL and VC) were
fixed. This was satisfactory at normal engine speeds, but posed problems at high
and low speeds. Since the VT did not vary with speed, the additional requirements
that arose at the extreme speeds could not be met with static VT. For example, at
high speeds, the engine requires greater amounts of air. This implies that the IV
should remain open for a longer period of time. This, though beneficial at high
speeds, would be a menace at low speeds as it may lead to exhaust of unburnt fuel,
which results in fuel wastage, increased emissions and lower performance.
This is where variable valve timing (VVT) comes into play. As the name
suggests, the timing of the valves is not fixed, but varies, as per the demands of the
situations. Therefore, the extra demands of the engine can be met, which in turn,
results in improved engine performance.

TYPES OF VVT MECHANISMS
1 Cam-Phasing VVT
Cam-phasing VVT is at present, the simplest, cheapest and most commonly used
mechanism. However, its performance gain is also the least. Basically, shifting the phase
angle of camshafts varies the valve timing. For example, at high speeds, the inlet camshaft
will be rotated in advance by 30° so as to enable earlier intake. This movement is controlled
by an engine management system according to need, and actuated by hydraulic valve gears.
Cam-phasing VVT cannot vary the duration of valve opening. It only allows earlier
or later valve opening. Earlier opening results in earlier close. It cannot vary the valve lift.
However, cam-phasing VVT is the simplest and cheapest form of VVT because each camshaft
needs only one hydraulic phasing actuator, unlike other systems that employ individual
mechanism for every cylinder.
Better systems have continuous variable shifting, say, any arbitrary value between
0° and 30°, depending on r.p.m. This provides the most suitable valve timing at any speed,
thus greatly enhancing engine flexibility. Moreover, the transition is so smooth that it is
hardly noticeable.

Two sets of cams having different shapes to enable different timing and
lift. One set operates during normal speed, say, below 4,500 r.p.m.. The
other set substitutes at higher speeds. Such layout does not allow
continuous change of timing, therefore the engine performs modestly
below 4,500 r.p.m.
2 Cam-Changing VVT
VVT-i (Variable Valve Timing - intelligent) as a revolutionary design
that increases engine torque and output while addressing environmental
issues. By adjusting the intake valve opening timing according to the
engine speed, more oxygen is supplied through the air intake valve as
more fuel is injected into the combustion chamber. Power and torque is
maximized due to larger scale combustion. This optimised fuel to air
ratio ensures the air-fuel mixture is combusted more thoroughly.
3 VVT-i (Variable Valve Timing–intelligent)

1. What are the functions of a frame?
• To support the chassis components and the body.
• To withstand static and dynamic loads without undue
deflection or distortion.
• To carry the load of the passengers or goods
carried in the body.
2. List out the various materials used in the
construction
of chassis frames.
Low Carbon Steel - 0.18 or 0.20 % carbon
content High Carbon Steel - 0.25 % carbon
content
Alloy Steel – With alloying elements like Ni & Cr
3.Write down any two main sections of vehicle
construction.
• Chassis construction
• Body construction
TWO MARKS

3. What are two types of vehicle suspensions?
3
4
• Rigid axle suspension
• Independent suspension
5. What loads are coming to axle?
• Vertical bending load due to vehicle weight
• Driving torque
• Braking torque
• Side thrust
6. What are the function of a gear box?
• It has to provide torque multiplication
• It has to provide neutral position
• It has to provide the means to reverse a
vehicle

7. Name the different kind of resistances to vehicle motion.
• Air resistance
• Rolling resistance
• Gradient resistance
8. Why is the frame narrow at front?
The frame is narrowed at the front to provide a better
steering lock.
This also permits smaller turning circle radius
9. List out the various materials used in the construction of vehicle
body
• Wood
• Metals
• Plastics
• Mixed construction of all these materials

10.What are the stresses to which the frame members
are subjected
to?
• Frame longitudinal members – bending stress
• Frame side members – twisting stress.
11. Name few components of engine.
• Cylinder block
• Cylinder head
• Crankcase
• Cylinder
• Piston
• Connecting rod
• Crankshaft
• Camshaft
• Valves
• Spark plug (in the case of petrol engine)
• Fuel injector (in the case of diesel engine)

12. Classify automobiles with respect to the drive of the
vehicle.
• Front wheel drive
• Rear wheel drive
• All four wheel drive
• Left hand drive
• Right hand drive
13. What is meant by the term Chassis?
A complete vehicle without a body structure is known as Chassis. It
comprises of basic structure, power unit, transmission system,
controls and auxiliaries.
14. How automobiles are classified into different types?
• Based on Make & Model
• Based on Fuel
• Based on Body Style
• Based on No. of Wheels
• Based on Drive

15. What are the two types of cylinder liners?
• Dry liners
• Wet liners
16. What are the functions of piston rings?
To provide a gas tight seal between the piston and cylinder
liner to prevent the escape of gases from top side of the piston to the
underside.
17. What are the two types of piston rings?
• Compression rings
• Oil rings

18. What is the function of piston and connecting rod?
• Piston – The piston assembly transfers the force from the
power stroke to the crankshaft
• Connecting rod – converts reciprocating motion of piston
into rotary motion of crankshaft
19. What is the function of Cylinder head?
• Cylinder head – it acts as a top cover to the cylinder
block. The valves are placed in the cylinder head in an
overhead valve engine.
20. What is VVT?
It is defined as the timing, or regulation of the
opening and closing of the valves. In simpler terms,
it is the way an engine 'breathes'.

ae chassis and automobile classification-converted.pptx

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