# Machine Dynamics Questions and Answers – Differential Band Brake

This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Differential Band Brake”.

1. When the fulcrum is between the two ends of a lever, the type of brake is _____
a) Simple band brake
b) Differential band brake
c) Shoe brake
d) Double block shoe brake

Explanation: When the fulcrum is at one end of the lever, the brake is called a simple band brake, whereas when the fulcrum is between the two ends it is known as differential band brake.

2. For a simple band brake, the fulcrum is at the end of the lever.
a) True
b) False

Explanation: For a simple band brake, the fulcrum is at the end of the lever and for a differential band brake, the fulcrum is between the ends of the lever.

3. For the given figure, the brake can sustain a torque of 350 N-m and coefficient of friction between the band and drum is 0.3, find necessary force required for clockwise rotation of the drum in N.

a) 32
b) 64
c) 96
d) 128

Explanation: 2.3 log(T1/T2) = μ.θ = 0.3×3.93 = 1.179
log(T1/T2) = 1.129/2.3
= 0.51
T1/T2 = 3.255
Braking torque = (T1-T2)r
T1-T2 = 2000
therefore T1 = 2887N T2 = 887N
Px500 = T2x150 – T1x35
P = 64N.

4. For the given figure, the brake can sustain a torque of 350 N-m and coefficient of friction between the band and drum is 0.3, If the drum rotates in anticlockwise direction, find force in N.

a) 804
b) 756
c) 850
d) 900

Explanation: 2.3 log(T1/T2) = μ.θ = 0.3×3.93 = 1.179
log(T1/T2) = 1.129/2.3
= 0.51
T1/T2 = 3.255
Braking torque = (T1-T2)r
T1-T2 = 2000
therefore T1 = 2887N T2 = 887N
Px500 = T1x150 – T2x35
P = 804N.

5. For the given figure, the brake can sustain a torque of 350 N-m and coefficient of friction between the band and drum is 0.3, find OA for self locking condition during clockwise rotation.

a) 114mm
b) 130mm
c) 57mm
d) 88mm

Explanation: For self locking condition, P=0
therefore T1x35 = T2xOA
OA = 114mm.
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6. Which of the following brake does not has self locking?
a) Disk
b) Differential band
c) Simple band
d) Depends on the acting force

Explanation: Disk brakes do not have self locking However, it is possible to achieve self locking in differential band brakes.

7. Braking torque is independent of the radius of drum.
a) True
b) False

Explanation: Braking torque is given by the equation
T = (T1-T2)r
hence it is directly proportional to the radius of the drum.

8. With the help of following data, calculate the braking torque in N-m.
T1 = 2500 N
T2 = 200 N
diameter of drum = 350mm
a) 402.5
b) 805
c) 201.5
d) 560

Explanation: T = T = (T1-T2)r
r = 350/2000
T = (2500-200)350/2000
= 2300×350/2000 N-m
= 402.5 N-m.

Sanfoundry Global Education & Learning Series – Machine Dynamics.