Machine Kinematics Question Bank on “Types of Belts – 2”.
1. In a multiple V- belt drive, when a single belt is damaged, it is preferable to change the complete set to
a) reduce vibration
b) reduce slip
c) ensure uniform loading
d) ensure proper alignment
Answer: c
Clarification: For uniform loading it is better to change the complete set of V-belt drive.
2. In a multiple V- belt drive, all the belts should stretch at the same rate.
a) True
b) False
Answer: a
Clarification: It may be noted that in multiple V-belt drive, all the belts should stretch at the same rate so that the load is equally divided between them.
3. The ratio of the driving tensions for V-belts is _____________ times that of flat belts.
a) sin β
b) cos β
c) cosec β
d) sec β
Answer: c
Clarification: None.
4. The ratio of driving tensions for rope drive is same as that of V-belt drive.
a) True
b) False
Answer: a
Clarification: None.
5. Creep in belt drive is due to
a) weak material of the belt
b) weak material of the pulley
c) uneven extensions and contractions of the belt when it passes from tight side to slack side
d) expansion of the belt
Answer: c
Clarification: None.
6. The centrifugal tension in belts
a) increases power transmitted
b) decreases power transmitted
c) have no effect on power transmitted
d) increases power transmitted upto a certain speed and then decreases
Answer: c
Clarification: In a high speed flat belt transmission, it would probably help. It is unlikely to add any significant power transmission in V- belts, as they rely on the wedging action of the belts in the pulley grooves. As the need for greater power transmission increases in a V- belt drive, the belts wedge harder into the pulleys, to respond.
7. When the belt is stationary, it is subjected to some tension known as initial tension. The value of this tension is equal to the
a) tension in the tight side of the belt
b) tension in the slack side of the belt
c) sum of the tensions on the tight side and slack side of the belt
d) average tension of the tight side and slack side of the belt
Answer: d
Clarification: None.
8. A pulley is connected to a power transmission shaft of diameter d by means of a rectangular sunk key of width w and length l. The width of the key is taken as d/4. For full power transmission, the shearing strength of the key is equal to the torsional shearing strength of the shaft. The ratio of the length of the key to the diameter of the shaft (l/d) is
a) п/4
b) п/6
c) п/2
d) п
Answer: a
Clarification: п/16 x ss x d3 = l x d/4 x ss x d/2
or, l/d = п/2.
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