PART – A

1. What strength of the material is to be considered while designing the spur gear parameter of minimum center

distance? Why?

2. Define the following with respect to the gear (a) Force along the line of action (b) Normal Module

3. Specify the reasons for backlash in gears.

4. Define the following with respect to the gear box (a) Preliminary ray diagram (b) Kinematic arrangement.

5. What is the difference between self-energizing and self-locking in case of block brakes?

6. What is the advantage of pivoted block brake over the rigid block brake?

7. How gears are classified based on shaft position?

8. Define the term back-lash in gears.

9. What are the various type of brakes?

10. Explain the self-locking phenomen in a single shoe brake.

11. How the function of a brake differs from that of the clutch?

12. Name the various facing materials for brakes.

13. Define virtual number of teeth for bevel gears.

14. Give the characteristics of corrected gears

15. What is meant by hypoid gear?

16. What is the usual magnitude of spiral angle in spiral bevel gears?

17. What is backstop in brake terminology?

18. What is an equivalent coefficient of friction used while designing long shoe brake drums?

19. What is wear strength of a gear tooth?

20. Define the following with respect to the gears

Normal module ; force along the line of action

21. What is the reason for choosing specifically 14.50 or 200 pressure angle involute gear?

22. What is the importance of ray/speed diagram?

23. Differentiate between leading shoe and trailing shoe in case of internal expanding shoe brake.

24. With simple sketch define transverse circular pitch and normal circular pitch

25. Distinguish between corrected and uncorrected gears.

26. What types of stresses are produced in a belt used for power transmission? Show the distribution of these stresses

by a suitable sketch.

27. What are the effects of clearance on the performance of a bearing?

28. Specify the reasons for backlash in gears

29. What is the advantage of pivoted block brake over the rigid block brake?

30. What is the difference between self-energizing and self-locking in case of block brakes?

PART – B

1. Design a gearbox of the headstock of a turret lathe having arrangement for 9 spindle speeds ranging from 315 rpm

to 1050 rpm. The drive is from an electric motor of 5 hp at 1500 rpm. Design should include the following :

(i) Preliminary ray diagram 2. Spur gear design 3. Kinematic arranagement.

2. A 360mm radius brake drum contacts a single shoe as shown in the figure and resists a torque of 225 Nm at 500 rpm. The coefficient of friction is 0.3. Determine (i) the normal reaction on the shoe,(ii) the force to be applied at the lever end for counter clock wise rotation of the drum if e=0(iii the force to be applied at the lever end for clock wise rotation of the drum if e= 40 mm,(iv) the force to be applied at the lever end for anti clock wise rotation of the drum if e= 40 mm

3. Design a 9 speed gear box for a minimum speed of 35 rpm and maximum speed of 1000 rpm. Draw the speed

diagram and indicate the number of teeth on each gear in a kinematic diagram.

4. Design a gear box with following specifications. Power 14.72 kW, Number of speeds =18, Minimum speed = 16

rpm, step ratio = 1.25, Motor speed = 1400 rpm. Sketch the layout of gear box and speed diagram. And also

calculate the diameter of the shafts and number of teeth on the gears.

5. Design a 12 speed gear box. The speeds can be laid from 10 to 450 rpm with ɸ = 1.4, the motor power is 7.4 kW at

1240 rpm.

(i) Construct the best ray diagram

(ii) Calculate the gear sizes of all stages

(iii) Calculate the shaft diameter

(iv) Estimate the maximum force acting at the gear at any stage and hence calculate the module of the

gears.

6. The internal expanding shoe brake in Fig.1 has drum diameter 250 mm, R = 100 mm and face width of the shoe =

28 rpm. Calculate the actuating force, torque capacity and the hinge pin reactions if Pmax = 1000 kPa and

coefficient of friction is 0.32.

7. In a band and block brake, the band is lined with 14 blocks, each of which subtends an angle of 20degrees at the

drum centre. One end of band is attached to the function of the brake lever and the other to a pin 150mm from the

fulcrum. Find the force required at the end of the lever 1 m long from the fulcrum to give a torque of 4kN-m. The

diameter of the brake drum is 1m and the co-efficient of friction between the blocks and the drum is 0.25.

8. In an automotive type internal – expanding double – shoe brake he face width of the friction lining is 40 mm and

the intensity of normal pressure is limited to 1 N/mm2 . The coefficient of friction is 0.32. The angle φ1 can be

assumed to be zero. Calculate (i) the actuating force P, and (ii) the torque – absorbing capacity of the brake.

9. In a milling machine, 18 different speeds in the range of 35 rpm and 650 rpm are required. Design a three stage

gear box with a standard step ratio. Sketch the layout of the gear box, indicating the number of teeth n each gear.

The gear box receives 3.6 kW from an electric motor running at 1,440 rpm. Sketch also the speed diagram.

10. A machine tool gear box is to have 9 speeds. The gear box is driven by an electric motor whose shaft rotational

speed is 1400 r.p.m. The gear box is connected to the motor by a belt drive. The maximum and minimum speeds

required at the gear box output are 1000 r.p.m. and 200 r.p.m. respectively. Suitable speed reduction can also be

provided in the belt drive. What is the step ratio and what are the values of 9 speeds? Sketch the arrangement.

Obtain the number of teeth on each gear and also the actual output speeds.