# Machine Design Questions and Answers – Belt Constructions

This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Belt Constructions”.

1. The layer of a belt is generally called as
a) Ply
b) Layer
c) Segment
d) Sediment

Explanation: Terminology.

2. Velocity ratio for chain drive is lesser than that for belts.
a) Yes
b) No
c) In some cases
d) Can’t be determined

Explanation: Velocity ratio for chain drives is about 15:1 while for belts it is around 7:1.

3. Fabric rubber belts are not widely used as they can’t be operated at high speeds.
a) They can’t be used at velocities 50m/s
b) They can be used at high velocities
c) Limiting velocity is 20m/s
d) None of the listed

Explanation: These belts can be operated at 300m/s.

4. Power transmitting capacity of V belts is more than that of flat belt.
a) Yes
b) No
c) Only for V angle > 15
d) None of the listed

Explanation: Coefficient of friction is 2.92times of flat belts in V belts for identical materials.

5. The optimum velocity of the belt for maximum transmission is given by √P/6m.
a) Yes
b) No, by replacing 6 by 3
c) Replacing 6 by 9
d) None of the listed

Explanation: It is given by √P/3m.

6. Creep is the slight absolute motion of the belt as it passes over the pulley.
a) Yes
b) No, it is a relative motion
c) None of the listed
d) It is absolute motion

Explanation: It is a relative and not absolute motion.

7. In horizontal belt, the loose side is generally kept on the bottom.
a) True
b) False

Explanation: Loose side is kept on the top so that arc of contact increases and hence efficiency of the drive increases.

8. Vertical drives are preferred over horizontal.
a) True
b) False

Explanation: In vertical drive, gravitational force on the belt causes slip which reduces the efficiency.

9. The law of belting states that the centreline of the belt when it approaches a pulley must not lie in the midplane of the pulley.
a) True
b) False

Explanation: The centreline must lie in the midplane.

10. It is possible to use the belting reverse direction without violating the law of belting.
a) True
b) False

Explanation: Law of belting is violated if belt is used in reverse direction.

11. A shorter centre distance is always preferred in belt drives.
a) Yes due to stability
b) No due to stability
c) Yes due to instability
d) No due to instability

Explanation: It is more stable and compact.

12. If velocity ratio is less than 3, then centre distance is given by D+.5d.
a) True
b) False

Explanation: It is given by D+1.5d.

13. If velocity ratio is more than 3, then centre distance is given by 2D.
a) By 3D
b) By D
c) By 4D
d) By 5D

Explanation: It is given by D.

14. Is it possible to reduce the centre distance as much as we want?
a) Yes power transmission increases
b) No
c) Can’t be cited
d) None of the listed

Explanation: It depends on physical dimension and the minimum angle of wrap required to transfer the required power.

15. The diameter of the shorter pulley in leather belt drive is 265mm. It is rotating at 1440 rpm. Calculate the velocity of the belt.
a) 25m/s
b) 20m/s
c) 30m/s
d) None of the mentioned

Explanation: v=πdn/60×1000.

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