# Machine Design Questions and Answers – Internal Expanding Brake

This set of Machine Design Questions for entrance exams focuses on “Internal Expanding Brake”.

1. The intensity of normal pressure between the friction lining and the brake drum at any point is proportional to square of the vertical distance from the pivot.
a) It is independent
b) Proportional to vertical distance linearly
c) Inversely proportion to vertical distance
d) None of the listed

Explanation: It is proportional to the vertical distance linearly.

2. The coefficient of friction in internally expanding brakes is constant.
a) True
b) No, it varies with increase in speed linearly
c) It decreases with increase in speed linearly
d) None of the listed

Explanation: Coefficient of friction is constant in these types of brakes.

3. The centrifugal force acting on the shoe can never be omitted.
a) True
b) Always omitted
c) Depends on the magnitude
d) There is no centrifugal force acting

Explanation: Centrifugal force on the internal expanding brakes is generally neglected as it is very small.

4. These kinds of brakes require little maintenance.
a) Yes
b) No
c) Very much maintenance is required
d) Depends on the working environment

Explanation: Very little maintenance is required as there is less wear.

5. In internally expanding brake, a large actuating force produces a small braking torque and hence this brake isn’t used generally.
a) True
b) No, small actuating braking torque is produces
c) Zero actuating force is required
d) None of the listed

Explanation: Small actuating force produce large braking torque.
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6. Heat dissipating capacity of internally expanding brakes is a problem.
a) True
b) No
c) There is no heat generated
d) Heat is convected away on its own

Explanation: It has relatively poor dissipation of heat.

7. Internally expanding brakes never suffer the problem of self-locking.
a) True
b) Wear might lead to self-locking
c) Brakes are never self-locked
d) None of the listed

Explanation: Due to improper design, wear may be caused which might lead to self-locking of brakes.

8. Moment of normal force and frictional forces about the pivot axis are 640000N-mm and 250000N-mm respectively. If force acts at a distance of 190mm from the pivoted point, calculate the actuating force.
a) 1078.6N
b) 2052.6N
c) 3223.5N
d) 4454.5N

Explanation: P=M(n)-M(f)/C.

a) True
b) False

10. Needles bearings have not much load capacity as they are quite small.
a) True
b) False

Explanation: Needle bearings have quite large loading capacity as compared to their size.

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