belt drives,ropes and chain drives

Question 1

are used to transmit power from one shaft to another
by means of pulleys which rotate at the same speed or at different
speeds.

Answer 1

belts or ropes

Question 2

The amount of power transmitted using a belt or ropes depends upon the following factors :

Answer 2

1. The velocity of the belt.
2. The tension under which the belt is placed on the pulleys.
3. The arc of contact between the belt and the smaller pulley.
4. The conditions under which the belt is used.

Question 3

the Following are the various important factors upon which the selection of a belt drive depends:

Answer 3

1. Speed of the driving and driven shafts,
2. Speed reduction ratio,
3. Power to be transmitted,
4. Centre distance between the shafts,
5. Positive drive requirements,
6. Shafts layout,
7. Space available, and
8. Service conditions.

Question 4

These are used to transmit small powers at belt speeds upto about 10 m/s as in
agricultural machines and small machine tools.

Answer 4

Light drives.

Question 5

These are used to transmit medium powers at belt speeds over 10 m/s but up to
22 m/s, as in machine tools.

Answer 5

Medium drives.

Question 6

These are used to transmit large powers at belt speeds above 22 m/s as in
compressors and generators.

Answer 6

Heavy drives.

Question 7

is mostly used in the factories and workshops, where
a moderate amount of power is to be transmitted, from one pulley to another when the two pulleys
are not more than 8 metres apart.

Answer 7

Flat belt.

Question 8

is mostly used in the factories and workshops, where a
great amount of power is to be transmitted, from one pulley to another, when the two pulleys are
very near to each other.

Answer 8

V- belt.

Question 9

is mostly used in the
factories and workshops, where a great amount of power is to be transmitted, from one pulley to
another, when the two pulleys are more than 8 metres apart.

Answer 9

Circular belt or rope.

Question 10

The most important material for flat belt is

Answer 10

leather.

Question 11

are cheaper and suitable in warm climates, in damp atmospheres and in exposed positions.
Since the cotton belts require little attention, therefore these belts are mostly used in farm
machinery, belt conveyor etc.

Answer 11

Cotton or fabric belts.

Question 12

are made of layers of fabric impregnated

with rubber composition and have a thin layer of rubber on the faces.

Answer 12

Rubber belt.

Question 13

These belts are similar to rubber belts except that balata

gum is used in place of rubber.

Answer 13

Balata belts.

Question 14

The coefficient of friction between the belt and the pulley depends upon the following factors:

Answer 14

1. The material of belt;
2. The material of pulley;
3. The slip of belt; and
4. The speed of belt.

Question 15

made by the manufacturer to form an endless belt, is preferred than other joints.

Answer 15

Cemented joint,

Question 16

is formed by punching holes in line across the belt, leaving a margin
between the edge and the holes.

Answer 16

laced joint

Question 17

is used for lacing

the two ends together to form a joint.

Answer 17

raw hide strip

Question 18

is made like a staple
connection. The points are driven through the flesh side of the belt
and clinched on the inside.

Answer 18

Metal laced joint

Question 19

is used with shafts arranged

parallel and rotating in the same direction.

Answer 19

Open belt drive.

Question 20

The lower side belt (because of more

tension) is known as

Answer 20

tight side

Question 21

the upper side belt (because of less tension) is known as

Answer 21

slack side.

Question 22

is used with shafts arranged parallel and

rotating in the opposite directions.

Answer 22

Crossed or twist belt drive.

Question 23

(also known as right angle belt drive), is used with shafts arranged at right angles and rotating in one definite direction.

Answer 23

Quarter turn belt drive

Question 24

(also known as jockey pulley drive), is used with
shafts arranged parallel and when an open belt drive can not
be used due to small angle of contact on the smaller pulley.

Answer 24

Belt drive with idler pulleys.

Question 25

is used when power is transmitted from one shaft

to another through a number of pulleys.

Answer 25

Compound belt drive.

Question 26

is used for changing the speed of

the driven shaft while the main or driving shaft runs at constant speed.

Answer 26

Stepped or cone pulley drive.

Question 27

is used when the driven or machine shaft is to be started or
stopped whenever desired without interfering with the driving
shaft.

Answer 27

Fast and loose pulley drive.

Question 28

a certain portion of the belt extends and it contracts
again when the belt passes from the tight side to the slack side. Due to these changes of length, there is a
relative motion between the belt and the pulley surfaces.

Answer 28

creep.