# 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 150.the maximum normal pressure at the mean radius
is 150  KN/m2.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/mm2.

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 150.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/mm2.

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 106 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/cm2

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

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 103 kPa for the mild steel

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