Clutch and Brake Design | Interview Question and Answers

Clutch and Brake Design | Interview, Viva , Oral Question and Answers

1. What factors should be considered when designing friction clutches? Or what are the desirable properties of friction material to be used for clutches.

(a)The friction materials for the clutch should have high coefficient of friction
(b) They should not be affected by moisture and oil.
(c) May be light in weight.
(d) Dissipate heat quickly.

2. Name four materials used for lining of friction surfaces in clutches.

1. Wood 2. Leather 3. Asbestos based friction materials 4. Powdered metal friction materials.

3. What is the function of clutch in a transmission system?

Clutch is machine component used as temporary coupling and is used mainly in automobiles for engaging and disengaging the driving shaft where periodical engagement is required.

4. What is meant by positive clutch?

Which transmits power from driving shaft to the driven shaft by jaws or teeth is called positive clutch.No slipping is there.

5. By what means, power is transmitted by clutches?

In clutches, power transmission is achieved through (a) Interlocking (b) Friction (c) Wedging

6. Why are cone clutches better than disc clutches?

Since the cone discs are having large frictional areas and they can transmit a larger torque than disc clutches with, the same diameter and actuating force and hence cone clutches are preferred over disk clutches. But usually cone clutches are mainly used in low peripheral applications.

7. Why should the generated heat be dissipated in clutch operation?

In order to save the friction plates and materials from melting by the heat produced during operation, the generated heat should be dissipated.

8. Name the two theories applied for the design of friction clutches.

1. Uniform Pressure theory
2. Uniform wear theory

9. In what ways, the clutches are different from brakes?

The clutch used to engage the driving and driven members and keep them moving (i.e., rotating) together, whereas brakes are employed to stop a moving member or reduce its speed.

10. What is the function of brake?

Brake is mechanical device by means of which motion of a body is retarded for slowing down or to bring it to rest, by applying artificial frictional resistance.

11. Give examples of radial and axial brakes.

Radial brakes: band brakes, block brakes, and internal expanding rim
Axial brakes: cone brakes and disc brakes.

12. What are the types of brake lining?

1. Organic lining
2. Semi-metallic lining
3. Metallic lining

13. What is a self locking brake?

When the frictional force is sufficient enough to apply the brake with no external forces, then the brake is said to be self locking brake.

14. What you meant by self energizing brake?

When the moment of applied force and moment of frictional force are in the same direction, then the frictional force helps in applying the brake. This type of brake is known as self energizing brake.

15. Two blocks diametrically opposite to each other are used in a block brake. Why?

If only one block is used for braking, then there will be side thrust on the bearings of wheel shaft. This drawback can be removed by providing two blocks on the two sides of the drum diametrically opposite.

16. If a multidisc clutch has 6 discs in driving shaft and 7 discs in driven shaft, then how many number of contact surfaces it will have?

Number of discs in driving shaft (n1) = 6
Number of discs in driven shaft (n2) = 7
Number of contact surfaces (n) = n1+n2-1= 6+7-1=12

17. Why in automobiles, braking action when traveling in reverse is not as effective as when moving forward?

When an automobiles moves forward, the braking force acts in the opposite direction to the direction of motion of the vehicle. whereas in reverse travelling the braking force acts in the same direction to the direction of motion of the vehicle.so it requires more braking force to apply brake.

18. Classify clutches based on the coupling methods.

(i) Mechanical clutch (ii) Pneumatic clutch (iii) Hydraulic clutch (iv) Electrical clutch