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PART A 10 X 2 = 20 marksAnswer ALL questions

1 What is Zero film bearing?

2 Enumerate the relative merits of V belts when compared with flat belt drives.

3 What do you understand by overhauling of screw?

4How the pressure angle of cams can be reduced?

5 Define Diametral pitch of a spur gear

6 How a helical gear differs from spur gear?

7 What is Miter Gear?

8 What is a ratchet and pawl mechanism?

9 What do you understand by preferred numbers?

10 What does the ray diagram of the gear box indicates?

Part B 5 *12 = 60 marks

Answer any FIVE questions, choosing ONE question from each unit

UNIT - I

11 Design a journal bearing for a centrifugal pump to the following specifications.

Journal diameter = 75 mm.

Speed of the journal = 1440 rpm.

Load on each journal = 11.5 KN

OR

12 Design a V belt drive for the following dimensions.

Driving 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.

UNIT II

13 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.

OR

14 A radial cam with a prime circle diameter of 150 mm rotates at 200 rpm. The follower

rises 50 mm with parabolic motion in 1200 of cam rotation. When the cam angle is 300,

find the value of pressure angle for

i. Radial follower

ii. Follower offset opposite the cam rotation equal to 10 mm.

UNIT III

15 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.

OR

16 Determine the geometric dimensions of a 6 station Geneva wheel for the driving

crank radius of 100 mm.

UNIT IV

17 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.

OR

18 Design a worm gear drive to transmit 20 KW at 1440 rpm. The speed of worm wheelis 60 rpm. The worm and wheel are made up of steel, bronze respectively. Select the

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number of starts as 3.

UNIT V

19 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.OR

20 Design a ratchet wheel for a winch using the following specifications.

Braking torque 150 Nm

Brake drum diameter 35 cm

Allowable bending stress for wheel 30 N/mm2

Number of teeth in the wheel 16

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