**DEPARTMENT OF AUTOMOBILE ENGINEERING**

**SUBJECT CODE / NAME: AU2352 / AUTOMOTIVE CHASSIS DESIGN**

**Question Bank**

**Semester: VI**

**PART – A**

1. Why a clutch is needed in the driveline of an automobile?

2. List out the factors governing the torque transmission capacity of a dry friction clutch.

3. Name different types of gears used in automobile transmission and give their relative

merits.

4. What are the differences between a constant mesh and sliding mesh gear train?

5. How are intermediate gears decided?

6. List out the various components of a clutch.

7. What are the materials for clutch lining?

8. Define the terms ‘traction and tractive effort’.

9.What is the condition for maximum traction?

10. Why is cone clutch more effective than single plate clutch?

11. Explain the difference between constant mesh gearbox and sliding mash gear box

**PART – B**

1.. Expalin the difference between centrifugal clutch and cone clutch. (8)

2. A single plate clutch is to have a maximum capacity of 56 KW at 1800r.p.m.The clutch

facing has a coefficient of friction of 0.4 and permissible of 207 KPa. The clutch is

engaged through 12 springs. Determine. The diameters of the clutch facing, if the inner

diameter is 0.7 times the outer. Find also the spring force of each spring when the

clutch is engaged.

3. A torque of 350 Nm is transmitted through a cone clutch having a mean diameter of

300 mm and semi- cone angle of 15

^{0}.the maximum normal pressure at the mean radius is 150 KN/m

^{2}.the coefficient of friction is 0.3 calculate the width of the contact surface. Also find the axial force to engage the clutch.

4. A gear box with three speeds forward and one reverse is to provide the speed reduction

as follows. top 5.1 :1, intermediate 8.8:1, low 16.5:1, reverse 19.8:1 with a

reduction5.1:1. at the rear axle. Assuming that the smallest pinion has not less than 15

than and speed of the lay shaft half that of main driving shaft , find the suitable

number of teeth of different wheels.

5. A centrifugal clutch is to transmit 15 KW at 900 r.p.m the shoes four in number.

The speed at which the engagement begins is ¾ th of the running speed. The inside

radius of the pulley rim is 150 mm and the centre of gravity of the shoe lies at 120mm

from the centre of the spider. The shoes are lined with ferrodo for which the co-

efficient of friction may be taken as 0.25 determine: 1. mass of the shoes, and 2. size

of the shoes, if angle subtended by the shoes at the centre of the spider is 60

^{0}and the pressure exerted on the shoes is 0.1 N/mm

^{2}.6 Explain the difference between constant mesh gearbox and sliding mash gear box

7 A single plate clutch is to have a maximum capacity of 60 KW at 1900 r.p.m. The

clutch facing has a coefficient of friction of 0.4 and permissible stress of 209 KPa .

The clutch is engaged through 12 springs. Determine. The diameters of the clutch

facing, if the inner diameter is 0.8 times the outer. Find also the spring force of each

spring when the clutch is engaged.

8 . A torque of 400 Nm is transmitted through a cone clutch having a mean diameter of

350 mm and semi- cone angle of 15

^{0}.the maximum normal pressure at the meanradius is 160 KN/M

^{2 }the coefficient of friction is 0.3 calculate the width of the contact surface. Also find the axial force to engage the clutch.

9. A gear box with three speeds forward and one reverse is to provide the speed

Reduction as follows. Top 5.1:1, intermediate 8.8:1, low 16.5:1, reverse 19.8:1 with

a reduction 5.5:1 at the rear axle. Assuming that the smallest pinion has not less

than 15 than and speed of the lay shaft half that of main driving shaft, find the

suitable number of teeth of different wheels.

10. A centrifugal clutch is to transmit 18 KW at 950 r.p.m the shoes four in number. The

Speed at which the engagement begins is ¾ th of the running speed. The inside radius

of the pulley rim is 160 mm and the centre of gravity of the shoe lies at 130 mm from

The centre of the spider. The shoes are lined with ferrodo for which the coefficient of

friction may be taken as 0.25 determine: 1. mass of the shoes, and 2. size of the

shoes, if angle subtended by the shoes at the centre of the spider is 60

^{0}and the pressure exerted on the shoes is 0.2 N/mm

^{2}.11. Calculate them maximum bending moment and maximum section modulus for the

side member of vehicle frame having channel section and the following particulars

Wheel base =180 cm

Overall length =360 cm

Equal over hang on either side

270 Kgf acting 45 cm in front of front axle

180 Kgf acting at 45 cm behind front axle

180 Kgf acting at 45 cm in front of rear axle

67.5 Kgf acting at 45 cm behind the rear axle

In addition there is a uniformly distributed load of 1.75 Kgf/cm run over the entire

length of the frame. Assume dynamic stress in twice as that of static stress.

12. A semi elliptical leaf spring of a vehicle as leaves of 75 mm width an 10 mm

thickness with an effective length of 900 mm. If the stress is not to exceed 220 725

Kpa when a spring is loaded to 4905 N, estimate the required number and spring

deflection under load. If the spring is just flat under the load find its initial radius of

curvature. Take E = 196.2 X 10

^{6}Kpa.13. The load distribution between the front and rear axle of a motor vehicle weighing

1350 Kgf is 48% load to the front axle and the remaining to the rear. The front wheel

track is 140 cm and the distance between the spring pads is 66 cm. Design a suitable

for I- section for a axle beam assuming the width of flange and its thickness are 0.6

and 0.2 of the overall depth of the section. The thickness of the web is 0.25 of the

width of the flange. Assume a working stress of 915 Kgf/cm

^{2}14. The wheel base and wheel track of a motor car are 284 cm and 142cm respectively.

The kingpins are 127 cm apart and the angle between the track arm and the

longitudinal axis of the car in the straight ahead position is 20°. Find the turning

circle radius of car.

15. A car pivot pins 1.14 m apart, the length of each track arms is 0.1525 m and the track

rod behind the axle is 1.04 m long. Determine the wheelbase for true rolling of all

wheels when the inner wheel stub axle is at 55° to the centre time of the car.

16. An automobile engine develops 30 kw at 1500 r.p.m and its bottom gear ratio is 3.06.

It a propeller shaft of 40 mm outside diameter is to be used, assuming a safe shear

stress of 55 X 10

^{3}kPa for the mild steel^{ }