Engineering Mechanics

Chapter 33 : Transmission of Power by Belts and Ropes „„„„„ 695

5. Deduce the relation between the tensions on the tight side and slack side of a belt connect-
   ing two pulleys and transmitting power. Neglect the centrifugal effect of the belt mass.


6. When a flat belt is about to slip over a pulley, show that the ratio of tension in the tight and
   slack side depends upon friction coefficient and angle of contact.


7. Define the term ‘initial tension’ in a belt. How would you find out the initial tensions in a
   belt?


8. What are the advantages of a rope drive?

OBJECTIVE TYPE QUESTIONS

1. The length of belt used in a cross belt drive is ..... than that used in open belt drive,
   provided distance between the two pulleys and their diameters remains the same.
   (a) less than (b) equal to (c) more than


2. The power transmitted by a belt depends upon
   (a) sum of the tensions in the tight side and slack side
   (b) difference of tension in the tight side and slack side
   (c) none of them


3. The relation between the tension in tight side (T 1 ) and slack side (T 2 ) of a belt drive is

(a)

2

1

T

e

T

= μθ

(b)

2

1

2·3 log

T

T

⎛⎞=μθ

⎜⎟

⎝⎠

(c) both of them (d) none of them

where μ= Coefficient of friction, and

θ= Angle of lap.

4. Which of the following statement is correct?

(a) The effect of centrifugal tension developed in a belt drive has no effect on the power

transmitted by it.

(b) The power developed is maximum when 1/3 of the maximum tension is absorbed as

centrifugal tension.

(c) The maximum tension in a belt drive is equal to the sum of tension in the tight side

and centrifugal tension.

(d) Both (b) and (c)

(e) All (a), (b) and (c)

5. In a rope drive, the relation between the tension in the tight side and slack side is

1

2

2·3 log sec

T

T

⎛⎞

⎜⎟=μθα

⎝⎠

where 2 α= Angle of groove.

(a) True (b) False

ANSWERS

1. (c) 2. (b) 3. (d) 4. (e) 5. (b)

Top