22656

22324
3 Hours / 70 Marks Seat No

Instructions – (1) All Questions are Compulsory.

(2) Answer each next main Question on a new page.
(3) Illustrate your answers with neat sketches wherever necessary.
(4) Figures to the right indicate full marks.
(5) Mobile Phone, Pager and any other Electronic Communication devices
are not permissible in Examination Hall.
1. Attempt any FIVE of the following. 10
c) Define :-i) Caster ii) Camber
Castor: It is forward or backward tilt of the wheel from true vertical
when viewed from the side of wheel.

Range (Amount): About 3 degree of castor gives good results.

(ii) Camber: It is the tilt of car wheels from the vertical when viewed from the front of vehicle.

Range (Amount): Camber should not exceed 2 degree.

e) State any two functions of Battery.

1. Battery supplies the current for cranking motor and ignition system when the engine is being
cranked for starting
2. When the vehicle is stationary battery supplies electricity for operating the various electrical
devices.
3. It is the secondary source of electrical energy when vehicle is not operating and generator speed
is insufficient to meet the full load requirement.

f) Define :- i) Public Service Vehicle. ii) Transport vehicle.

Public service vehicle: Vehicle used to travel public from one place to another place
Transport vehicle: Vehicle used to transport goods from one place to another place

g) Name any four major components of transmission system used in automobile

1. Clutch
2. Gear box
3. Propeller shaft
4. Universal joint
5. Differential

k) Define sprung weight and unsprung weight.

sprung weight :-It is the weight supported by the spring. (Anything carried by the weight of
springs.), which includes; the weight of the frame, body, engine, and entire transmission system.
unsprung weight:- It is the weight of other parts of the vehicle which is not supported by springs,
including; the weight of the rear axle assembly, steering knuckle, front axle, wheels, tires, and
brakes

l) State the function of sensor in automobile.

[1] Mass airflow Sensor: Use to calculate the air density in the engine.
[2] Engine Speed Sensor: Use to monitor the crankshaft rotation speed.
[3] Oxygen Sensor: Use to monitor the content of exhaust gases.
[4] Coolant Sensor: Use to check temp. of coolant.
[5] Voltage Sensor: Use to manage the car idling speed.

m) State the duties and responsibilities of RTO.

Role of RTO
1. To maintain a database of registered vehicles.
2. Mechanical inspection of accidental vehicles.
3. To grant a certificate of fitness to transport vehicles.
4. To issue International driving permits.
5. To routinely inspect vehicles.
6. Checking emissions and issuing pollution certificates for vehicles.
7. To conduct the driving test, issue Learner’s, Permanent driver’s licenses and

n) State working principle of clutch.

Working Principle of Centrifugal Clutch:
The centrifugal clutch operates on a principle of centrifugal force, instead of spring force for keeping
it in the engaged position. The force acting away from the center; is known as a Centrifugal force.
Centrifugal clutch does not require a clutch pedal for operation. The clutch is operated automatically
depending on the engine speed. The vehicle can be stopped in gear without stalling the engine.
Similarly, the vehicle can be started in any gear by pressing the accelerator pedal. This makes the
driving operation very easy.
 a) Define vehicle layout.
Vehicle layout refers to the arrangement of a vehicle's main components, including the engine, clutch,
gearbox, final drive, and suspension. It also encompasses the location of the engine (front, mid, rear)
and the drive wheels (front, rear, all-wheel drive). The specific layout influences factors like weight
distribution, handling, and space efficiency.
b) State brake fade.
Brake fade is a temporary reduction in braking power, often caused by excessive heat generated
during repeated or sustained braking, especially in high-speed or high-load conditions. It's
characterized by a spongy brake pedal and increased stopping distance.

c) Enlist any four requirements of suspension system in automobile.

1) To absorb and damps various vibrations, oscillations and shocks.
2) To transmit braking and driving torque to body frame.
3) To support the body on axles.
4) To provide appropriate road grip.
5) To avoid excessive rolling, pitching and bouncing.
6) To provide stability on slopes and turns.
7) To provide maximum comfort to the driver and passenger.

d) Enlist any four electrical components of Automobile.

Alternator Battery Starter motor

Car body electrical system Fuse Starter
Infotainment systems Charging system Electrical wiring
Electronic fuel injection Ignition system Lighting
Wiring harness Auxiliary battery Electric motor
Inverter Regenerative braking system Air Conditioner Blower

Charger Converters Fuel pump

Relays Safety and security systems Thermal management
system

e) State necessity of vehicle registration.

Vehicle registration is necessary to establish legal ownership, allow the vehicle to be driven on
public roads, and enable tracking in case of accidents or theft. It also ensures compliance with
road and environmental regulations, facilitating verification of insurance, pollution control
certificates, and fitness certifications.
f) Define HGV and MGV.
Heavy Goods Vehicle (HGV):
HGV means any goods carriage with the gross vehicle weight of which or a tractor or a road roller
the unladen weight of either of which, exceeds 12,000 kg.
Medium Goods Vehicle (MGV):
MGV means any goods carriage other than a light motor vehicle or a heavy goods vehicle.
g) State need of universal joint and slip joint used in propeller shaft.
Function of Universal Joint-
Universal joint allows transmission of power and rotary motion at an angle which varies as a
vehicle encounters a bump.
Function of Slip Joint-
This joint allows variation in length of the propeller shaft when vehicle came across road
irregularities.
2. Attempt any THREE of the following.
b) List various parts of synchromesh gear box with role of each component.

c) Describe working of Disk Brake. Draw a neat sketch.

Motor vehicles are now fitted with disc brakes instead of conventional drum brakes. Disc brakes
use friction to create braking power. Disc brakes create braking power by forcing flat friction pads
against the sides of the rotating disc. Disc brake mainly consists of, (i) Rotor (ii) Caliper, and (iii)
Brake pads. In between each piston & disc, a friction pad is held in position by springs. When the
brakes are applied, hydraulically actuated pistons move the friction pads into contact with the
discs, applying equal and opposite forces on the latter. On releasing the brakes, the rubber sealing
rings act as return springs and retract the pistons and the friction pads away from the disc

d) Explain working of gas filled shock absorbers in brief. Draw a simple sketch for
the same.

Gas-Filled Shock Absorber:

The gas-filled shock absorber is a hydraulic shock absorber that is charged with gas. The principal
gas used in nitrogen is kept under either; Low pressure (10-15 Kg/cm2) or High pressure (20-30
Kg/cm2).
Working of Gas-Filled Shock Absorber during Bounding (Compression):
The piston rod moves downward, causing the pressure of the fluid to be higher in the lower
chamber than in the upper chamber. Therefore, the fluid in the lower chamber is forced into the
upper chamber through the piston valve. At this time, the damping force is generated by the flow
resistance of the valve. The high-pressure gas exerts great pressure on the fluid in the lower
chamber, forcing it to flow quickly & smoothly into the upper chamber. This ensures a stable
damping force.
Working of Gas Filled Shock Absorber during Rebounding (Expansion):
The piston rod moves upward causing the fluid pressure in the upper chamber to be higher than
that in the lower chamber. Therefore, the fluid in the upper chamber is forced into the lower
chamber through the piston valve and the resistance exerted by the valve acts as a damping force.
Since the rod moves upward, a portion of it moves out of the cylinder, so the volume of fluid
displaced by it decreases. To compensate for this, the free piston is pushed upward by a distance
equivalent to this volume.

Figure: Monotube Type Gas Filled Shock Absorber

a) Classify automobiles.
i. On the basis of fuel used:

1. Diesel Vehicle
2. Petrol Vehicle
3. Gasoline Vehicle
4. Electric Vehicle
5. Duel Fuel Vehicles
ii. On the basis of capacity:
1. Light Commercial Vehicles (LCV)
2. Heavy Commercial Vehicles (HCV)
iii. On the basis of transmission:
1. Conventional Transmission using Gearbox
2. Semi –Automatic Transmission
3. Fully Automatic Transmission
iv. On the basis of drive:
1. Left Hand Drive
2. Right Hand Drive
3. Rear Wheel Drive
4. Front Wheel Drive
5. All Wheel Drive

b) Explain working of ABS.

The Anti-lock Braking System, commonly known as ABS, is an essential automobile safety feature
designed to prevent wheel locking and uncontrolled skidding during braking. The purpose of anti-lock
braking system is to allow greater manoeuvrability in emergency braking situations by enabling
steering control while braking. The key advantages of ABS lie in providing enhanced vehicle control
and reducing stopping distances on both dry and slippery surfaces. With ABS installed, the risk of
skidding diminishes significantly, ensuring better steering control during braking, a feat that even
skilled drivers may struggle to achieve without this technology. By employing ABS, ordinary drivers
can now effectively prevent skidding on dry and slippery roads, granting them superior steering
control during braking manoeuvres.

c) Describe the working of Mac. Phersonsturt type suspensionwith neat sketch.

In this type of Suspension system only lower wishbone is used. A Strut containing shock absorber
and the spring carries also the stub axle on which wheel is mounted. The Wishbone is hinged to
the cross member. The wishbone positions the wheel as well as resists accelerating, braking and
side forces. This type of suspension system is firstly used in Maruti 800. This type of Suspension
with anti-roll bar as employed in Volkswagen jetta and passat car.
Advantages :
1)It is a simple in construction.
2)Wheel camber does not very much.
3)It's maintenance is very easy.
4)It's Light moving parts help the wheel of follow the road irregularities.
Disadvantages:
1) Increases tyre weak
2)Quality of ride depends upon shock absorber.
3) Special equipment is required to check steering angle accurately.
4) cannot withstand heavy load.

b) Explain working of semi floating rear axle with neat sketch.

Semi floating Rear Axle

The figure shows a schematic diagram of the semi floating rear axle. A single ball bearing
is inside the axle casing. The axle of the wheel is at the centre of the axle casing and the wheels
are fitted at the end of the axle. This is done by means of key, bolt and nut. The whole weight of
the vehicle is first transmitted to the suspension spring. From there it is transmitted to the axle
casing from there to the axle and wheel. Finally it is transmitted to the ground. The axle can be
removed by first placing a support below the axle casing.

d) Describe working of wishbone type suspension system with neat sketch.

The wishbone type is the most popular independent suspension system.
It consists of two (occasionally parallel) wishbone-shaped arms to locate the wheel. Each wishbone
or arm has two mounting points to the chassis and one joint at the knuckle.
The shock absorber and coil spring mount to the wishbones to control vertical movement.
The vehicle weight is transmitted from the body and the cross member to the coil spring through
which it goes to the lower wishbone member.
The wishbones not only position the wheels and transmit the vehicle load but also rest acceleration,
braking and cornering forces.
The upper arms are shorter in length then the lower ones. This helps to keep the wheel track
constant thereby avoiding the tyre scrub thus minimizing wear.

e) Describe various types of alternative fuels for auto engines.

1. Gaseous Fuels:
Natural Gas: Compressed Natural Gas (CNG) and Liquified Natural Gas (LNG) are common
choices, offering lower emissions and potentially lower costs compared to gasoline.
Liquified Petroleum Gas (LPG): Propane is a readily available alternative, similar to CNG in its
benefits. Hydrogen: A clean-burning fuel, but requires specialized storage and infrastructure.
2. Alcohols:
Ethanol: Produced from crops and can be blended with gasoline in flexible fuel vehicles.
Methanol: A fuel with lower viscosity than gasoline, making it easy to blend and atomize.
Butanol: Another potential alternative fuel for internal combustion engines.
3. Vegetable and Waste-Derived Oils:
Biodiesel: A renewable fuel made from vegetable oils, animal fats, or recycled cooking grease,
suitable for diesel engines.
4. Electricity:
Electric Vehicles (EVs):All-electric and plug-in hybrid electric vehicles offer zero tailpipe
emissions.
Fuel Cells:Convert chemical energy into electrical energy, producing only water as a byproduct.
Other Considerations:
Hybrid Vehicles: Combine internal combustion engines with electric motors and batteries,
offering improved fuel efficiency.
Dual-Fuel Systems: Allow vehicles to switch between different fuels, providing flexibility.
Fuels derived from natural gas: Include liquid fuels and synthetic fuels.

f) Explain the working of constant mesh type gear box with neat sketch.
Working of constant mesh gear box: In this type of gear box, all the gears are in constant
mesh with the corresponding gears on the lay shaft. The gears on the main shaft which is splined
are free. The dog clutches are provided which are free to slide on the main shaft. The gears on the
lay shaft are fixed.
When the left dog clutch is slide to left by means of the selector mechanism,its teeth are engaged
with those on the clutch gear & we get the direct gear. The same dog clutch when slide to right
makes contact with the second gear & second gear is obtained. Similarly movement of the right
dog clutch to the left results in low gear & towards right in reverse gear.

g) Discuss the classification of brakes from different consideration.

Classification by Purpose:
Service or Primary Brakes:
These are the main brakes used to slow down or stop a moving vehicle. They are typically foot-
operated.
Parking or Secondary Brakes:
These brakes are used to hold the vehicle stationary, especially on inclines. They are often hand-
operated and referred to as hand brakes.
Classification by Construction:
Drum Brakes:
These brakes use a drum-shaped component that rotates with the wheel and brake shoes that press
against the drum to create friction.
Disc Brakes:
These brakes use a rotating disc (rotor) that is gripped by brake pads, which are pressed together
by calipers to create friction.
Classification by Actuation Method:
Mechanical Brakes: These brakes use a system of rods, levers, and linkages to apply pressure.
Hydraulic Brakes: These brakes use brake fluid to transmit pressure from the brake pedal to the
wheel brakes.
Electric or Brake-by-Wire Brakes: These brakes use electrical signals to control the braking
force.
Pneumatic Brakes: These brakes use compressed air to apply the brakes, commonly found in
heavy vehicles.
Vacuum Brakes: These brakes use vacuum pressure to reduce the effort required to apply the
brakes.
Classification by Force Type:
Frictional Brakes: These brakes rely on friction between moving parts to slow down or stop the
vehicle.
Electromagnetic Brakes: These brakes use electromagnetic fields to create braking force.
Hydraulic Brakes: These brakes use hydraulic pressure to transfer force from the brake pedal to
the wheel brakes.

(a) State the necessity of transmission system in automobile.

 The necessity of a transmission system in an automobile lies in its ability to efficiently transfer the
engine's power to the wheels, enabling smooth and controlled movement, and adapting to varying
driving conditions. The transmission system is crucial for changing speed and direction, allowing
for variable gear ratios, and facilitating smooth acceleration and deceleration
 Power Transfer:
The transmission system acts as the bridge between the engine and the wheels, transmitting the
rotational power produced by the engine to the axles and ultimately to the wheels, enabling the
vehicle to move.
 Speed Control:
The transmission allows the driver to select different gear ratios, which change the speed and
torque delivered to the wheels. Lower gears provide more torque for acceleration, while higher
gears allow for higher speeds.
 Direction Control:
The transmission facilitates changing direction by enabling reverse gear, which is essential for
backing up and maneuvering.
 Smooth Operation:
The transmission ensures smooth acceleration and deceleration by gradually engaging and
disengaging gears, preventing jerky movements.
 Driving Condition Adaptation:
The variable gear ratios allow the transmission to adapt to different driving conditions, such as
hills or uneven terrain, by adjusting the torque and speed delivered to the wheels.
 Efficiency:
A well-functioning transmission system contributes to fuel economy by ensuring that the engine
operates at an optimal speed and load.
(d) Draw neat labelled layout of air brake system.

WORKING:
As shown in the figure, in the air brakes the compressed air (around 700 kPa) is used to actuate the
brake mechanism. The figure shows the complete layout of the Air Brake System. It consists of Air
filter, unloading valve, Air compressor, Air reservoir, Brake valve, and 4 numbers brake chamber. The
compressor takes atmospheric air through the air filter and compresses the air. This air is stored under
pressure in the air reservoir. From this reservoir air goes to various accessories of the vehicle which
operates on compressed air. Part of the air goes to the brake valve. The control of the brake valve is
done by a driver who controls the intensity of braking according to an emergency.
Pedal Depressed: When the brake pedal is depressed, compressed air from the reservoir is transmitted
through pipes equally in all directions to the brake chambers through brake valve which further applies
the brake.
Pedal Released: When the driver releases the brake pedal, the master cylinder piston returns to its
original position due to return spring, and the pressure is dropped. It releases brake shoes from brake
drum to their: original position and brakes are released

3. Attempt any THREE of the following. 12

a) Explain following terms related with car Aerodynamics.

i) Drag ii) Lift

(i) Drag: It is the largest and most important aerodynamic force encountered by a vehicle
at normal highway speeds. The major factors included in aerodynamic drag are-Induced
drag, profile drag, and Friction drag. It depends on the shape of the body. Air drag is given
by the equation,
DA = ½ ρ V2 CD A
Where, ρ= Density of air
V= Speed of Vehicle
CD = Coefficient of Drag
A= Frontal Area of the vehicle

ii) Lift: The pressure difference from the top to bottom of the vehicle causes the lift force.
The lift force is measured at the centerline of the vehicle at the center of the wheelbase.
The aerodynamic lift and pitching moment are undesirable effects. The lift force is given
by the equation,
LA = ½ ρ V2 CL A
Where, ρ= Density of air
V= Total wind velocity
CL = Lift Coefficient
A= Frontal Area of the vehicle
b) Explain Rack and Pinion type steeri ng gear box with neat sketch.

Figure: Rack and Pinion steering gear

Construction: In this type of steering gear box, a pinion is mounted at the end of the steering
shaft. The pinion engages with rack which is provided with ball joint at its each end in order to
allow for the rise and fall of wheel. The rotary motion of the steering wheel is transmitted to the
pinion. The circular motion of pinion is convert into the linear rack movement, which further
transmitted to tie rods to the stub axle through ball joint. This type of steering gear box provides
sufficiently low gear reduction for car and it is quiet suitable even for heavier motor vehicle if
assisted with power. It occupies very less space and less number of linkages.
Working: The rack-and-pinion steering box has a pinion, connected to the steering column.
This pinion runs in mesh with a rack that is connected to the steering tie rods. Both the pinion and
the rack teeth are helical gears. Helical gearing gives smoother and quieter operation for the
driver. Turning the steering wheel rotates the pinion, and moves the rack from side to side.Ball
joints at the end of the rack locate the tie-rods and allow movement in the steering and suspension.
Mechanical advantage is gained by the reduction ratio. The value of this ratio depends on the size
of the pinion. A small pinion gives light steering, but it requires many turns of the steering wheel
to travel from lock, to lock. A large pinion means the number of turns of the steering column is
reduced, but the steering is heavier to turn.
Uses: All most all small cars like maruti 800, Alto, Wagon R, SweftDezire, i10 etc houses this
type of steering gearbox.
c) State function and need of independent suspension system.

Function of Independent Suspension System:

1. It has light moving parts that help the wheel to follow the road irregularities.
2. The Unsprung weight is low.
3. It absorbs road shocks or impacts due to bumping in the road by oscillation.
4. Tires also provide a spring effect, but to a smaller extent.
5. It set the parameters like camber, caster, and kingpin inclination for better steering
Quality.
6. Axle should not tilt and the wheel remains vertical.
 7. It reduces the shocks to passengers and gives a comfortable ride, also reducing additional
stresses in the automobile frame body.
8. It requires a more rigid subframe or chassis frame.
Need for Independent Suspension System:
1. In order to provide a comfortable ride to the passenger and avoid additional stresses in the
vehicle frame.
2. The vehicle should neither bounce nor roll or sway the passengers when cornering nor pitch
when accelerating, braking or suddenly lifting or dropping of the front wheel with respect to the
rear wheel.
3. Although some of the road irregularities and inequalities are absorbed by large tires.
4. It may provide a softer suspension because the low spring rate (stiffness) enables large wheel
movement.
5. In this the engine and chassis frame can be placed relatively lower which means the engine
position can be moved forward so more space for the passenger.
6. The unsprung weight is low.

a) Draw and explain vehicle layout of front engine rear wheel drive.

b) Sketch telescopic shock absorber and label main parts.

c) Draw a labled sketch of indicator light circuit and explain its working.
d) Explain working of battery ignition system with neat sketch.

The current creates a magnetic field around the soft iron core of the coil. As the breaker points
open, the current flows through the condenser; when they close, the current flows through the
contact breaker.
1 Ignition Switch: -- It is used for ON or OFF the engine. One end of the switch is connected
with the Primary Winding of Ignition Coil via Ballast Resistor, and every other stop is attached
with the Battery.
2 Battery:--The battery is provided for supply the initial current to the ignition device greater
especially ignition coil. Generally, the voltage of the battery is 6V or 12V or 24 V. In a vehicle
lead-acid Battery use widely
3 Ignition coil: -- The main purpose of it is to step up battery voltage so that it is sufficient for
generates the spark.
It is working as a step-up transformer, and has two winds, one is primary which have a lesser turn,
and the other one is secondary which have a higher number of turn.
4 Ballast resistors: -- This is used to limit the current in the ignition circuit and generally made of
Iron. It is placed in series between the Ignition Switch and Ignition Coil. However, it is used in old
automobile vehicles.
 5 Contact Breakers: -- The contact breaker is an electrical switch which is regulated by the cam
and when the breaker is open, current flows through and the condenser charges it.
6 Distributors: -- It is used in the multi-cylinder engine, and its purpose is to regulate spark in
each spark plug at the correct sequence.
7 Capacitor: -- A capacitor is a storing device where electrical energy is stored. It is fitted parallel
to the contact breaker, while the current drops then it supplied the extra current so that the spark is
produced. It is product of metallic plates separated with the aid of using air or every other
insulating material.
8 Spark Plug: -- the actual Spark is generated for the combustion of Fuel or Charge. If there may
be greater than one spark plug exists then everyone is connected one at a time with the distributor
and offers the spark in the sequence .

e) Explain with neat sketch working of power steering.

o 1. Steering Wheel and Column:

The driver rotates the steering wheel, which is connected to the steering column. This rotation is
then transferred to a steering gearbox.
o 2. Hydraulic Pump:
When the steering wheel is turned, a hydraulic pump, driven by the engine, starts to pump
pressurized fluid through the system.
o 3. Rack and Pinion (Steering Gearbox):
A key component that converts the hydraulic force into mechanical movement is the steering
gearbox, often known as a rack and pinion. The pinion gear, which is connected to the steering
column, meshes with the rack gear. As the pinion rotates, it causes the rack to move back and
forth.
o 4. Hydraulic Cylinder and Piston:
The high-pressure fluid from the pump enters a hydraulic cylinder, which contains a piston. The
fluid pushes the piston, moving it and applying force to the rack.
o 5. Directional Control:
The amount of force applied to the piston is determined by the driver's input on the steering
wheel. The steering wheel controls a valve that regulates the flow of fluid to the cylinder,
allowing the driver to steer in the desired direction.
o 6. Steering Knuckle and Tie Rods:
The movement of the rack, caused by the piston and hydraulic pressure, is then transferred to the
front wheels via steering knuckles and tie rods, allowing the driver to steer the vehicle.
 o 7. Return Flow and Cooling:
After steering the wheels, the hydraulic fluid flows back through return hoses to the reservoir,
where it is cooled and ready for the next steering maneuver.

g) Discuss in details various factors affecting tyre life.

Factors affecting Tire Life:

[1] Inflation Pressure:
The tyre must be run on specified air pressure given by the manufacturer. If tyre inflated with less
pressure i.e. Under Inflated Pressure it will result in :
(i) More flexing
(ii)Uneven tread wear
(iii)More tyre wear on sides
(iv) Cracking of the side wall
(v) Lack of directional stability
(vi) Increased rolling resistance.
(vii) If tyre is inflated with more tyre pressure i.e. Over Inflated Pressure it will result in;
(viii)Reduces the road grip
(ix) Less cushioning effect
(x) Reduce the tread contact area
(xi) More wear in the center of the tread
[2] Wheel Alignment:
Due to improper wheel alignment rapid wear of tyre thread takes place. Unequal camber results in
excessive wear of tyre by pulling the wheels to one side. Too little or too much castor causes the
wheel to wander resulting in spotty wear. If wheel balancing is not proper uneven load will occur
on tyres, again radial and lateral run-out will also cause wear of the tyres. Badly adjusted brakes
result in faster tyre wear in spots. The brake heat may also cause the failure of the tube and valve.
[3] Overloading
In case of overloading the tyre has an insufficient amount of air to support the dead weight arried.
This results in a decrease in tyre mileage.
[4] Driving manners:
This includes sudden acceleration, high speeds, sudden braking, driving on bad roads, etc. all
cause faster tread wear

(c) Differentiate between disc brake and drum brake.

 (d) Explain with neat sketch working of differential.

1. When vehicle moves in a straight line:

The power comes from propeller shaft to the bevel pinion which drives the crown wheel. Then it
is carried to the differential cage in which a set of planet pinions and sun gears are located. From
the sun gear it is transmitted to the road wheels through axle half shafts. In this case, the crown
wheel, differential cage, planet pinions and sun gears all turn as a single unit and there is no any
relative motion between the sun gear and planet pinion. The planet pinions do not rotate about
their own axis. The road wheels, half shafts and sun wheels offer the same resistance to being
turned and the differential gearing does not therefore operate. Both the road wheels turn at the
same speed.
2. When Vehicle takes a turn:
The inner wheel experiences a resistance and tends to rotate in opposite direction. Due to this the
planet pinions starts rotating about their own axis and around the sun gear and transmit more
rotary motion to the outer side sun gear. So that outer sun gear rotates faster than the inner sun
gear. Therefore the outer road wheel runs faster than the inner road wheel and covers a more
distance to negotiate a turn safely.
(a) Describe with neat sketch working of alternator.
 Working Principle: An alternator, also known as a synchronous generator, is a machine that
converts mechanical energy into electrical energy in the form of alternating current (AC)
1. Mechanical Energy Input:
The alternator is driven by a prime mover (like a turbine or engine) that provides mechanical
energy to the rotor.
2. Rotor's Magnetic Field:
The rotor's field windings are energized by a DC source (like an exciter) to create a rotating
magnetic field.
3. Stator's Winding:
The stator windings are stationary coils of wire that are strategically positioned within the rotating
magnetic field.
4. Induced EMF:
As the rotor rotates, the magnetic field cuts across the stator windings, inducing an alternating
electromotive force (EMF) in them.
5. Three-Phase AC Output:
Due to the arrangement of the stator windings, a three-phase AC voltage is produced. This voltage
is then connected to a power grid or other electrical loads.

(b) Differentiate between radial ply and cross ply tyres.

(e) Draw the general layout of an automobile Chasis and label the components.

A 4-wheel drive system works by transferring power to all 4 wheels through a gearing
arrangement known as differentials. The engine connects to these differentials by a drive shaft,
which feeds the power to the wheels using the drive axles. To increase the effective use of the
vehicle required to travel on rough unconstructed roads and trucks, a special arrangement known
as four-wheel drive is provided. Due to all four wheels getting driven, the whole weight of the
vehicle is available for traction. The system is provided in jeeps which are known all-wheel drive
vehicles. These vehicles are also called off-road vehicles as it is constructed mainly for the
purpose of unformed or off-road driving conditions. Example: Mahindra Scorpio, Gypsy,
Mahindra Bolero etc.
4. Attempt any TWO of the following. 12
a) Explain working principle of electric vehicles.
Electric vehicles (EVs) work by converting stored electrical energy into mechanical energy to
power the wheels. This is achieved through a battery that stores electricity, an electric motor that
uses that electricity to spin, and a controller that manages the power flow to the motor. When the
driver presses the accelerator, the controller sends a signal to the motor, which then spins the
wheels and propels the vehicle forward.
b) Explain construction and working of bendix drive.
It is a starting device.
- Bendix drives are the inertia drives in which the starter motor pinion is made to engage or
disengage with the toothed rings on the periphery of the engine flywheel.- Drive head is keyed to
the end of armature shaft. When current is passed to the starting motor (commutator and armature
assembly), the armature shaft starts revolving at full speed.
- When pinion travels to the end of thread, it strikes the collar at left & forced to turn with the
thread sleeve. This causes the flywheel & crankshaft to turn & crank the engine.
- Immediately after starting the engine the unbalanced weight pinion returns to its initial position
because speed of flywheel is more than speed of unbalanced weight pin

c) Describe organization structure of motor vehicle department (RTO).

 e) Write salient features of motor vehicles Act 1988

Objectives of the Motor Vehicle Act, 1988 :-- (any four)

The Indian Motor Vehicle Act of 1988 was established to solve the following issues/objectives.
1) Sticking to strict procedures for granting licences and calculating the validity period of such
licences.
2) To maintain road safety requirements.
3) Dangerous and explosive material transportation rules,
4) Pollution control measures, Third party liability, and Vehicle registration.
5) To maintain the country’s rapidly growing quantity of personal and commercial cars.
6) To raise the amount of compensation available to hit-and-run cases.
7) To eliminate the time limit for traffic accident victims to file compensation claim.

a) Explain necessity and importance of Cable Color Codes in automobile.

a) Compare CNG vehicle with LPG vehicle on the basis of following parameters:-
i) Energy content of fuel ii) Density iii) Chemical formula of fueliv)Application
 g) State any four advantages and disadvantages of electric vehicles.

h) Draw a neat sketch of traffic sign STOP and NO PARKING.

5. Attempt any TWO of the following. 12
b) State need of ABS. Draw typical layout of ABS. Write in brief role different
components.
Need of ABS
It is also known as anti-skid braking system. Wheels skid when they slow down faster than
the vehicle.To prevent skidding of the vehicle the wheels must not be lock up. This is the
purpose of antilock braking system.

Role of Different Components:-

1. Electronic Control Unit (ECU)
It is heart of ABS. It monitors and controls antilock brake function when required. Its
function based on input from wheel speed sensors and hydraulic unit to decide whether
antilock operation is necessary or not.
2. Accumulator
 It is used to maintain high pressure in braking system by storing hydraulic fluid.It also
provides residual pressure for power assisted braking.
3. Wheel Speed Sensor
It is mounted on each wheel.
It is used to measure speed of wheel.
It sends signal to ECU.
4. Hydraulic Unit
The brake lines from the master cylinder are connected to it.
It modulates the brake pressure as per the signals provided by the ECU.

b) State wheel Balancing and wheel Alignment Describe it’s procedure.

Wheel balancing, A tyre balance corrects the weight imbalance on your tyre and wheel
assemblies, Wheel balancing is the process of attaching small weight's to a wheel's rim to
distribute the weight of the wheels evenly on each axle. This means that as a wheel rotates
the full circumference of the tyre is in contact with the road ensuring a consistent wearing
of the tyres across the width.
Procedure for balancing is as follows
1. Turn on , the balancer.
2. Clean the tire, rim flange and wheel.
3. Mount the tire/wheel assembly on a balancer.
4. Enter the A & D wheel dimensions.
5. Enter width wheel dimensions.
6. Lower the hood to spin the wheel and check dimensions.
7. Raise the hood after the tire stops rotating.
8. Add/remove required weight on wheel rim.

Wheel alignment:-alignment corrects the angles of the tires so they always come in contact
with the road in the right way.
Three primary types of wheel Alignment exist:
Toe Alignment: This focuses on the angle of the tires when viewed from above the vehicle
or car.
Camber Alignment: Camber refers to the vertical angle of the tire.
Caster Alignment: The caster measures the steering axis's forward or backward tilt when
viewed from the side.
These alignments are carried out by Dunlop alignment Equipment or now a days by
computerized setup is used. Initial misalignments are verified and angles are maintained as
per specifications.
Procedure for wheel alignment is as follows
1.front wheels are true running and wheel bearings are properly adjusted
2.tyres are inflated as specified.
3.front suspension springs are properly seated and ball joints are not excessively loose.
4.vehicle is laden or un laden condition as recommended by manufacturer.
5.surface level must be perfect leveled.
Following gauge should be used
a)wheel alignment gauge
b)camber gauge
c)castor and king pin gauge

c) Explain the working of diaphragm type clutch with neat sketch.

 A diaphragm clutch uses a diaphragm spring (a special crown-shaped spring) instead of
multiple coil springs to engage and disengage the clutch. When engaged, the diaphragm
spring holds the pressure plate against the clutch disc, transmitting power between the
engine and transmission. Disengaging the clutch, typically by pressing the clutch pedal,
causes the diaphragm spring to deform, releasing the pressure and allowing the clutch disc
to separate from the flywheel.

Working Principle:

1. Engagement:
When the clutch pedal is not pressed, the diaphragm spring exerts a force on the pressure
plate, holding it against the clutch disc and flywheel. This creates friction, transmitting
power from the engine to the wheels.
2. Disengagement:
Pressing the clutch pedal applies a force to the release bearing, which in turn pushes on the
center of the diaphragm spring. The diaphragm spring deforms, causing the outer edges to
move away from the pressure plate. This reduces the pressure between the pressure plate
and the clutch disc, allowing them to separate.
3. Release:
When the clutch pedal is released, the diaphragm spring returns to its original shape,
applying pressure on the pressure plate and engaging the clutch again

(b) Explain with neat sketch hydraulic braking system. Also, state any two
advantages and two disadvantages of hydraulic brake system.
1) Brake pedal.
2) Master cylinder.
3) Oil reservoir.
4) Steel pipe lines, unions and flexible hoses
5) Wheel cylinder.
6) Brake shoe.
7) Disk or Drum brake.
Construction: There are two main chambers viz. the fluid reservoir and compression
chamber in which the piston operates. There are rubber seals on both ends of the piston in
the compression chamber. The reduced diameter region of the piston is always surrounded
by the fluid. A rubber boot covers the push rod end of the master cylinder to prevent the
dust from entering inside. Towards the brake line side of the compression chamber, there
is a fluid check valve with a rubber cup inside.
Working:
The push rod is operated with the foot brake pedal through linkage. As the pedal is
pressed, push rod moves the piston to the left against the force of the spring till it covers
the bypass port. Further movement f the push rod causes building up of pressure in the
compression chamber. Finally, when sufficient pressure has built up, the inner rubber cup
of the fluid check valve is deflected, forcing the fluid under pressure in the lines. This fluid
enters the wheel cylinder or the caliper and moves the piston thereby applying the brakes.

Advantages
Increased braking force.
Simple in construction.
Low wear rate of brake linings.
Flexibility of brake linings.
Increased mechanical advantage.

Dis- Advantage
Whole braking system fails due to leakage of fluid from brake linings.
Presence of air inside the tubings ruins the whole system.

c)Enlist various types of vehicle layout and explain with neat sketch front engine rear
wheel drive layout.
the four types of vehicle layout.
1. Front engine front wheel drive (FEFWD)
2. Rear engine rear Wheel Drive (RERWD)
3. Front engine rear wheel drive (FERWD)
4. All wheel drive or Four wheel drive(4WD)
(c) Explain with neat sketch construction and working of overdrive .

An overdrive unit is an epicyclic gear set, typically installed between the gearbox and the
propeller shaft in a vehicle, that increases the output speed of the propeller shaft when
engaged, allowing for lower engine RPM at higher speeds, improving fuel economy and
reducing engine wear. It uses sun, planet, and annulus gears to achieve this, with a
freewheel assembly (overrunning clutch) enabling the unit to operate independently of the
engine's RPM.
Construction:
An overdrive unit generally consists of the following components:
 Sun Gear: Connected to the input shaft, it meshes with the planet gears.
 Planet Gears: Meshed with both the sun gear and the annulus gear, they rotate around the
annulus gear.
 Annulus Gear: Internal gear that is usually fixed to the output shaft.
 Planet Carrier: Holds the planet gears and rotates with them.
 Freewheel Assembly (Overrunning Clutch): Allows the overdrive unit to operate
independently of the engine's RPM.
 Control Mechanism (Hydraulic or Electric): Enables engagement and disengagement of
the overdrive.
Working Principle:
1. Disengaged (Direct Drive):When disengaged, the freewheel is locked, and the input shaft
directly drives the output shaft through the gearbox, providing a 1:1 gear ratio.
2. Engaged (Overdrive):When engaged, the freewheel unlocks, allowing the annulus gear
(connected to the output shaft) to rotate faster than the input shaft (connected to the sun gear)
due to the planetary gear train. This results in a higher output speed from the overdrive unit
than the input speed from the gearbox, effectively reducing engine RPM at higher speeds.

6. Attempt any THREE of the following. 12

b) Draw electronic ignition system. Compare it with conventional ignition systems.

(Any four Points).
Electronic ignition system
● Electronic ignition systems use some solid state devices like transistors and capacitors,
etc. to generate the right sparking voltage at right time.
● These systems have overcome the limitations of conventional (battery ignition and
magneto-ignition) ignition systems. Modern automobiles make use of these systems. Two
systems, common in use, are:
a. Capacitive discharge ignition and
b. Transistorized coil ignition.
● These systems are more reliable and require less maintenance. Wear and tear of
components are reduced the and life of spark plugs is increased with the use of electronic
ignition.

Compare it with a Conventional ignition system (Any four points)

a. Because of arcing, pitting of contact breaker point and which will lead to regular
maintenance problems.
b. Poor starting: After a few thousand kilometers of running, the timing becomes
inaccurate, which results in poor starting (Starting trouble).
c. At very high engine speeds, performance is poor because of the inertia effects of the
moving parts in the system.
d. Sometimes it is not possible to produce spark properly in fouled spark plugs.

c) Describe in brief different passenger safety systems adapted in modern vehicles

Passenger Comfort and Safety Systems:

[1] Air Bags:
Airbags are passive safety features designed. Airbags are strong fabric bags that are folded
and concealed behind various parts inside the vehicle. Many vehicles have a driver airbag
in the steering column and a front-passenger airbag in the dashboard. Newer vehicles may
also have side airbags located in the interior side panels, the roof, or the doors.
Features of Air Bags:
It provides added protection to seatbelts. It reduces injury by either cushioning the
occupant’s contact with the interior of the vehicle or preventing contact completely in the
event of a crash. It inflates and deflates very rapidly in the event of a severe crash.
[2] Seat Belts:
Seatbelts are a passive vehicle safety feature designed to minimize the severity of injuries
sustained by drivers and passengers in the event of a crash. When a vehicle stops or
 accelerates suddenly, a great deal of force is placed on everything inside the vehicle,
including the people in the vehicle. Seatbelts help to reduce the effects of this force by
distributing it across the strongest parts of the body – the chest and pelvis
Features of Seat Belts:
It helps to prevent injuries resulting from colliding with other objects or people in the
vehicle. It prevents the ejection of the occupant from the vehicle, which can often result in
fatal injury. It prevents or minimizes the second impact in a crash, which causes injuries.
The working of seat belts in case of immediate braking.
[3] Collapsible Steering Column:
The collapsible steering column is a type of advanced steering column. It is a part of the
passive safety system in cars. Most passenger vehicles commonly employ the collapsible
version instead of the regular steering column. It is also known as an ‘Energy absorbing
steering column’.
Features of Collapsible Steering Column:
It reduces the risk of injuries occurring to the driver in case of frontal impacts by
collapsing. Energy dissipation management in the event of a frontal collision. Provide
mounting for the multi-function switch, column lock, column wiring, column shroud,
transmission gear selector, gauges, etc. Offer (height and/or length) adjustment to suit
driver preference.
[4] Anti-lock Braking System (ABS) with EBD:
When a brake is applied suddenly with huge force the wheels get locked and go out of
control resulting in an accident. ABS with electronic brake-force distribution prevents the
wheels from locking and skidding. Ensuring better control even during sudden braking.
[5] Electronic Stability Control (ESC):
Many car accidents happen because the car loses control due to oversteer or understeer in
corners, low traction in wet roads, etc. ESC monitors the steering wheel angle along with
the car’s individual wheel rotation. During an emergency, ESC applies the brake and
balances the engine power to regain control.
6.Adjustable Steering:
When you are behind the wheel, you need to be comfortable. Having adjustable steering
commonly known as tilt and telescopic steering will help the driver to adjust the height of
the steering wheel and the distance from the driver. This reduces any sort of discomfort to
the driver.
7.Tyre Pressure Monitoring System (TPMS):
A sensor is placed in each wheel to monitor the tyre pressure. TPMS sends an alert to the
instrument cluster when the tyre pressure is low. It increases your car’s safety on the road
with better handling, reduced braking distance and better fuel economy.

a) Explain construction and working of differential with neat sketch.

 Construction of standard differential –
As shown in the above figure, there are various parts in this differential unit. This is an
open differential. A pinion gear is mounted on the pinion shaft. Actually, this pinion shaft
is a propeller shaft. This pinion gear rotates the big ring gear. A Carrier unit is mounted on
the ring gear. It consists of two bevel pinions (planet pinions) and two bevels (sun) gears.
The sun bevel gears are connected with the half shaft of the rear axle. A differential
housing covers this whole assembly. And axle housing covers the half shaft.

Working of Differential :-
The power is transferred from engine’s drive shaft to pinion gear, since the pinion gear &
ring gear are meshed, power flows to ring gear.As the spider gear is connected with the
ring gear, power flows to it. Finally from the spider gear, power gets transferred to both
the side gears.
When a vehicle moves on a straight path, the differential gear assembly (whole assembly)
turns as a unit. The ring gear, both differential side gears and both axles are in this unit.
The two planet pinions do not rotate with the pinion shaft. Because they apply the same
force on the sun pinions. Therefore, both sun pinions rotate at the same rpm with the ring
gear.
During the right turn, the vehicle’s right (inside) wheel rotates slower than the left
(outside) wheel. Inside of the differential case, the planet pinion rotates on its self-axis
along with the ring gear. This allows the independent rotation of both side wheels. As the
carrier rotates with the ring gear, the planet pinion rotates at the same rpm. But, due to the
pinion’s spinning on the self-axis, it reduces the rpm of the right sun gear and increases the
rpm of the left sun gear. The vice-versa action happens while the vehicle turns left. the
plane pinion reduces the rpm of the left side sun gear and increases the right side sun ears
rpm.

b) List the main component of lead acid battery. Explain its construction with neat sketch.

1.Separator
2. Electrolyte
3. Container
4. Cover of cell
5. Vent plug
6. Connecting bar
7 terminal posts
 Construction: it consist following components
1.Separator: It is most important part of lead acid battery. Which separate the positive and
negative plates from each other and prevents the short circuit? The separators must be porous so
that the electrolyte may circulate between the plates . The separators must have higher insulating
resistance and mechanical strength. The material used for separators are wood, rubber, glass wood
mate, pvc.
2. Electrolyte: in lead acid battery dilute sulphuric acid (H2SO4)is used as an electrolyte. For this
purpose one part concentrated sulphuric acid is mixed with three parts of distilled water.
3. Container: Container is a box of vulcanized rubber, molded rubber, molded plastic, glass or
ceramic , on the base of this box there are supports block on which the positive and negative
plates are established. Thus between this supports there are grooves which works like a mud box.
The active material separated from the plates get collected in this mud box and it cannot make the
contact with the plates thus the internal faults due to the mud are avoided.
4. Cover of cell: In lead acid battery it is also made of the same material which is used is used for
making container. It is used to cover the complete cell after the installation of the plates in it . it
protects the cell from the dust as well as other external impurities.
5. Vent plug: The vent plug are provide in the cover plate of the cell which are used to fill up the
electrolyte in the cell or the inspection of internal condition of the cell the vent plugs are also use
for to exhaust the gases generated in the cell to the atmosphere.

c) Explain different types of vehicle maintenance

o
are four types of vehicle maintenance namely :
1. Preventive maintenance
2. Break maintenance
3. Periodic maintenance or schedule maintenance
4. Operation Maintenance
1. Preventive maintenance :
Prevention without breakdown or without giving trouble on road some attention or maintenance
taken to the vehicle is called as preventive maintenance. It intends to reduce or totally eliminate
breakdown and accidents due to mechanical failure and reduces repair cost. This type of
maintenance is done to prevent problems from occurring in the future. It involves routine checks,
adjustments, and replacements of various components and fluids, such as oil changes, tire
rotations, and brake inspections.
A good preventive maintenance program lead to following advantages:
A) Reduce the breakdown of vehicle.
B) Increase safety due to reduced breakdown.
C) Less expenses on repairs.
D) Good control on inventory of spare parts.
E) Lesser number of equipment are require.
2. Breakdown maintenance :
Break down maintenance is a attention which is to be provided when the motor vehicle
becomes immobilized due to fault created during running. These fault are started
difficulties, puncture, Electrical fault, carburetor and fuel supply fault, overheating, fan
belting, breakage and accident etc.
3. Periodic maintenance :
Periodic maintenance or operatives maintenance is attentions provided attention provide to
motor vehicles after in operation for a specified time or covered distance.
4 Operations and maintenance
Operations and maintenance usually includes tasks to maintain equipment before
significant issues arise, such as inspections, cleaning, minor part replacement, lubrication,
and fluid monitoring.

f) Explain the role and responsibilities of service supervisor.

1) Managing all team members to ensure that the station performs at its best, every day.
2) Leading the team in providing a great guest experience through excellent service.
3) Managing every aspect of the station operation safely and efficiently.
4) Ability to work effectively and communicate with superiors, subordinates & customers.
5) Observe the day-to-day workflow and assignments of service staff.
6) Conducts performance evaluations that are timely and constructive.
7) Handles discipline and termination of employees as needed and in accordance with company
policy.
8) Maintain preventive maintenance records and part inventory.
9) Estimate repair cost and services completed in a timely manner

(a) Explain with neat sketch construction and working of starting motor.

Working of Vehicle Starting System:

The starting or cranking system consists of starting motor, battery, control switch,
and interconnecting wiring. The starting system is the heart of the electrical system
in automobiles. The key is inserted into the ignition switch and turned to the start
position a small number of current passes through the neutral safety switch to the
starter relay or starter solenoid. The Starter solenoid allows high current to flow
through the battery cable to the starter motor. The starter motor cranks the engine so
that the piston moving downward, can create suction that draws the air-fuel mixture
into the cylinder.