Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MD2 > FLAT BELT DRIVE PPT > Flashcards

FLAT BELT DRIVE PPT Flashcards

1
Q

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

A

Belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The amount of power transmitted depends upon the following factors:

A
  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.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

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

A

Light drives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

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

A

Medium drives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

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

A

Heavy drives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The ________ 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.

A

Flat belt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The ________ 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

A

V-belt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The ____________ 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.

A

Circular belt or rope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

must be strong, flexible, and durable; and must have a high coefficient of friction.

A

Materials Used for Belts:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

it is the most important material for flat belt. The hair side of the leather is smoother and harder, but the flesh side is stronger. The fibres on the hair side are perpendicular to the surface, while those on the flesh side are interwoven and parallel to the surface. Therefore, the hair side of a belt should be in contact with the pulley surface which places the greatest tensile strength of the belt section on the outside, where the tension is maximum as the belt passes over the pulley.

A

Leather belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The leather may be either

A
  1. oak-tanned or
  2. mineral salt-tanned e.g. chrome-tanned.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The ________ are made by folding canvass or cotton duck to three or more layers (depending upon the thickness desired) and stitching together. They are impregnated with some filler like linseed oil in order to make the belt water-proof and to prevent injury to the fibres. The ________ require little attention, therefore these belts are mostly used in farm machinery, belt conveyor etc.

A

Cotton or fabric belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

It is made of layers of fabric impregnated with rubber composition and have a thin layer of rubber on the faces. These belts are very flexible but are quickly destroyed if allowed to come into contact with heat, oil or grease. One of the principle advantage of these belts is that they may be easily made endless. These belts are found suitable for saw mills, paper mills where they are exposed to moisture.

A

Rubber belt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

These belts are similar to rubber belts except that balata gum is used in place of rubber. They are acid proof and water proof. They should not be at temperatures above 40°C because they begin to soften and become sticky. The strength of ____________ is 25 per cent higher than rubber belts

A

Balata belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The ultimate strength of leather belt varies from 21 to 35 MPa
and a factor of safety may be taken as 8 to 10. However, the
wear life of a belt is more important than actual strength. It has been shown by experience that under average conditions an allowable stress of 2.8 MPa or less will give a reasonable belt life. An allowable stress of 1.75 MPa may be expected to give a belt life of about 15 years.

A

Working Stresses in Belts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

As the speed of belt increases, the centrifugal force also
increases which tries to pull the belt away from the pulley.
* This will result in the decrease of power transmitted by the
belt.
* It has been found that for the efficient transmission of power, the ________ 20 m/s to 22.5 m/s may be used.As the speed of belt increases, the centrifugal force also increases which tries to pull the belt away from the pulley.
* This will result in the decrease of power transmitted by the belt.
* It has been found that for the efficient transmission of power, the ________ 20 m/s to 22.5 m/s may be used.

A

Belt Speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The ________________________ depends upon the following factors:
1. The material of belt;
2. The material of pulley;
3. The slip of belt; and
4. The speed of belt.

A

Coefficient of Friction Between Belt and Pulley

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Standard Belt Thicknesses and Widths

for nominal belt widths of 35 to 63 mm

A

5 mm

19
Q

Standard Belt Thicknesses and Widths

for nominal belt widths of 50 to 140 mm

A

6.5 mm

20
Q

Standard Belt Thicknesses and Widths

for nominal belt widths of 90 to 224 mm,

A

8 mm

21
Q

Standard Belt Thicknesses and Widths

for nominal belt widths of 125 to 400 mm

A

10 mm

22
Q

Standard Belt Thicknesses and Widths

for nominal belt widths of 250 to 600 mm

A

12 mm

23
Q

For English Units:
* The width varies by :

increments from ½ to1 in.

A

1/8 in

24
Q

For English Units:
* The width varies by :

increments from 1 to 4 in.

A

¼ in

25
Q

For English Units:
* The width varies by :

increments from 4 to 7 in.

A

½ in.

26
Q

For English Units:
* The width varies by :

increments from 7 to 12 in.

A

1 in.

27
Q

When the endless belts are not available, then the belts are
cut from big rolls and the ends are joined together by fasteners.

A

Belt Joints

28
Q

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

A

Cemented joint

29
Q

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

A

Laced joint

30
Q

is used for lacing the two ends together to form a straight-stitch raw hide laced joint.

A

raw hide strip

31
Q

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

A

Metal laced joint

32
Q

metal hinges may be fastened to the belt ends and connected by a steel or fibre pin.

A

Metal joint

33
Q

is used with shafts arranged parallel and rotating in the same direction.

A

Open belt drive

34
Q

is used with shafts arranged parallel and rotating in the opposite directions.

A

Crossed or twist belt drive

35
Q

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

A

Quarter turn belt drive

36
Q

(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

A

Belt drive with idler pulleys

37
Q

is used when power is transmitted from one shaft to another through a number of pulleys.

A

Compound belt drive

38
Q

is used for changing the speed of the driven shaft while the main or driving shaft runs at constant speed. This is accomplished by shifting the belt from one part of the steps to the other.

A

Stepped or cone pulley drive

39
Q

Sometimes, the frictional grip between the belts and the pulleys becomes insufficient.
* This may cause some forward motion of the driver without carrying the belt with it. It is generally expressed as a percentage.
* As the slipping of the belt is a common phenomenon, thus the belt should never be used where a definite velocity ratio is of importance (as in the case of hour, minute and second arms in a watch).

A

Slip of the Belt

40
Q

When the belt passes from the slack side to the tight side, 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.
* This relative motion is termed as creep.
* The total effect of creep is to reduce slightly the speed of the driven pulley or follower.

A

Creep of Belt

41
Q

Since the belt continuously runs over the pulleys, therefore, some centrifugal force is caused, whose effect is to increase the tension on both the tight as well as the slack sides.
* The tension caused by centrifugal force
* At lower belt speeds (less than 10 m/s), the ____________ is very small, but at higher belt speeds (more than 10 m/s), its effect is considerable and thus should be taken into account.

A

Centrifugal Tension

42
Q

The max. stressinduced on the belt is caused by the max. tension in the belt FT1 , w/c is the total tension at tight side when centrifugal tension is considered

A

Maximum Stress on the Belt

43
Q

Even when the pulleys are stationary, the belt is subjected to some tension, called initial tension.
* When the driver starts rotating, it pulls the belt from one side (increasing tension in the belt on this side) and delivers to the other side (decreasing tension in the belt on that side).

A

Initial Tension in the Belt

MD2 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions