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REGULATION : 2003
B.E. DEGREE EXAMINATION, APRIL / MAY 2007
Mechanical Engineering
03M603 Design of Transmission Systems
Use of Approved Data book is permitted
Time : Three hours Max: 5 x 20 = 100
marks
Answer ALL questions
UNIT I
1.a. Enumerate the relative merits of V belts when compared with
flat belt drives.
2 marks
1.b. Design a V belt drive for the following dimensions. 18
marksDriving pulley diameter : 500 mm
Driven pulley diameter : 150 mm
Speed of driving pulley : 300 rpm
Center distance : 925 mm
Power to be transmitted : 7.5 kW.
OR
2.a. List out the factors influencing the selection of belt
drive. 2 marks
2.b. Design a chain drive to run a compressor from a 11 kW
electric motor running at 970
rpm. The speed of compressor is 330 rpm. The compressor operates
16 hours / day.
The center distance is about 500 mm. The tension in the chain
may be adjusted by
shifting the motor on rails. 18 marks
UNIT II
3.a. Define Diametral pitch of a spur gear 2 marks
3.b. Design a straight spur gear drive for transmitting a power
of 8 kW with a pinion speed
of 764 rpm. Speed ratio is 2. The gears are to be made of C45
steel. Life is to be 10,000
hours. 18 marks
OR
4.a. Define backlash of a spur gear drive. 2 marks
4.b. A pair of straight teeth spur gears is to transmit 20 kW
when the pinion rotates at 300
rpm. The velocity ratio is 1:3. The allowable static stresses
for the pinion and gear
materials are 120 MPa and 100MPa respectively. The pinion has 15
teeth and its face
width is 14 times the module. Determine the design variables of
both pinion and gear
from the standpoint of view of strength only, with out taking
into consideration of the
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effect of the dynamic loading. 18 marks
UNIT III
5.a. How a helical gear differs from spur gear? 2 marks
5.b. Design a bevel gear drive to transmit 3.5 kW. Speed ratio =
4. Driving shaft speed is
200 rpm. The drive is non reversible. The pinion is made of
Steel whereas wheel is of
CI. Assume a life of 25,000 hrs. 18 marks
OR
6.a. What is Miter Gear? 2 marks
6.b. Design a worm gear drive to transmit 22.5 kW at a worm
speed of 1440 rpm. Velocity
ratio is 24:1. An efficiency of at least 85% is desired. The
temperature rise should be
restricted to 400C. 18 marks
UNIT IV
7.a. What do you understand by preferred numbers? 2 marks
7.b. The spindle of a pillar drill is to run at 12 different
speeds in the range of 100 rpm and
355 rpm. Design a three stage gear box with a standard step
ratio. Sketch the layout of
the gear box, indicating the number of teeth on each gear. The
gear box receives 5 kW
from an electric motor running at 360 rpm. Sketch also the speed
diagram.
18 marks
OR
8.a. What does the ray diagram of the gear box indicates? 2
marks
8.b. Draw the kinematic diagram and speed diagram of the gear
box in a head stock of a
lathe having 9 spindle speeds ranging from 31.5 rpm to 1050 rpm.
Calculate the
number of teeth on all gears if the minimum number of teeth is
25. Also calculate the
% of deviation in speeds. 18 marks
UNIT V
9.a. List the desirable characteristics of brake lining
material. - 6 marks
9.b. A leather faced conical clutch has cone angle of 300. The
pressure between the contact
surface is limited to 0.35 N/mm2 and the breadth of the conical
surface is not to exceed
1/3rd of the mean radius. Determine the dimensions of the
contact surface to transmit 22
kW at 2000 rpm. Also calculate the force required to engage the
clutch. Take the
coefficient of friction as 0.15. 14 marksOR
10.a. What are the desirable characteristics of friction
surfaces? 6 marks
10.b. A differential band brake is to be used for a winch
lifting a load of 45 kN through a
rope wound around a barrel of 500 mm in diameter. The brake drum
to be keyed to the
same shaft is to be 600 mm in diameter and the angle of lap of
the brake band over the
drum is 2500 approximately. Determine the width and thickness of
the band. Operating
arms of the brake are 40 mm and 200 mm and the operating lever
is 1.5 m long.
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