AUTOMOTIVE CHASSIS AND SUSPENSION (NAU601)
Time: 3 Hours Max Marks: 100
SECTION – A (Short Answer Questions)
(10 × 2 = 20 Marks)
(a) Over steering and under steering
Over steering: When the vehicle turns more sharply than intended, causing the rear wheels to skid outward.
Under steering: When the vehicle turns less than intended, causing the front wheels to skid.
(b) Hotchkiss drive
Hotchkiss drive is a rear-wheel drive system in which the propeller shaft transmits torque to the
differential, and the leaf springs take driving and braking thrust.
(c) King pin inclination
King pin inclination is the angle between the king pin axis and the vertical line when viewed from the front of the vehicle. It helps in self-centering of wheels and reduces steering effort.
(d) Torque capacity
Torque capacity is the maximum torque that a clutch or transmission component can transmit without slipping.
(e) Functions of gearbox
Main functions of gearbox are: Provide variable speed and torque
Allow reverse motion Enable neutral position
(f) Wheel track
Wheel track is the distance between the centers of the left and right wheels on the same axle.
(g) Function of differential
A differential allows rear wheels to rotate at different speeds while taking turns and transmits torque to both wheels.
(h) Slip joint
Slip joint allows axial movement of the propeller shaft to accommodate changes in distance due to suspension movement.
(i) Function of vibration dampers
Vibration dampers (shock absorbers) control oscillations of springs, providing ride comfort and vehicle stability.
(j) Purpose of stub axles
Stub axles support the front wheels, allow steering movement, and transmit load from the wheels to the front axle.
SECTION – B (Long Answer Questions)
(Attempt any FIVE – 5 × 10 = 50 Marks)
2(a) Chassis frame – functions, types, and loads
Functions of chassis frame: Support vehicle components
Carry loads Maintain alignment
Withstand shocks and vibrations
Types of frames: Ladder frame
Box frame Tubular frame
Backbone frame
Loads acting on frame: Static load
Dynamic load
Torsional load Bending load
2(b) Torque converter and its application
A torque converter is a hydrodynamic device that transmits and multiplies torque using fluid.
Components: Impeller
Turbine Stator
Applications:
Automatic transmission vehicles Heavy-duty vehicles
Buses and luxury cars
2(c) Air bleeding and master cylinder
Air bleeding:
It is the process of removing air bubbles from hydraulic brake lines to ensure effective braking.
Master cylinder construction: Reservoir
Piston Return spring
Seals It converts pedal force into hydraulic pressure.
2(d) Steering gear boxes & rack and pinion
Types of steering gear boxes: Worm and wheel
Worm and sector Rack and pinion
Recirculating ball
Rack and pinion working:
Rotational motion of steering wheel is converted into linear motion, providing precise steering and less effort.
2(e) Epicyclic gearbox
An epicyclic gearbox consists of: Sun gear
Planet gears Ring gear
Working:
By holding different elements stationary, different speed ratios are obtained. Used in automatic
transmissions.
2(f) Power brake and servo system
Power brake:
Uses external power to reduce driver effort.
Servo system:
Uses vacuum or hydraulic pressure to multiply braking force, improving braking efficiency.
2(g) Wheel balancing and tubeless tyre
Wheel balancing:
Process of equalizing weight distribution to avoid vibration.
Tubeless tyre vs normal tyre: No inner tube
Reduced air leakage Better heat dissipation
Improved safety
2(h) Short notes
(i) Independent suspension system
Each wheel moves independently, improving ride comfort and handling.
(ii) Fluid coupling
Hydrodynamic device that transmits power smoothly without mechanical contact.
SECTION – C (Very Long Answer Questions)
(Attempt any TWO – 2 × 15 = 30 Marks)
3. Clutch – need, requirements, and types
Need of clutch: Engage/disengage engine from transmission
Smooth starting Gear shifting
Requirements of good clutch: High torque capacity
Smooth engagement Good heat dissipation
Minimum wear
Types of clutches: Single plate clutch
Multi-plate clutch Centrifugal clutch
Cone clutch
4. Transfer gearbox and propeller shaft
Purpose of transfer gearbox: Distribute power to all wheels
Provide high and low gear ratios Used in four-wheel-drive vehicles.
Propeller shaft functions:
Transmit power from gearbox to differential Accommodate angular and length variations
5. Suspension system elements and vehicle motions
Elements of suspension system: Springs
Shock absorbers Control arms
Stabilizer bars
Suspension movements: Bouncing: Vertical movement
Rolling: Sideways tilting during turns Pitching: Forward/backward tilting during braking or acceleration
Suspension improves comfort, safety, and road handling.
