Aide Memoire. Rule

Multiply the value of C from the following table by the stress in pounds.

Proportion of Are embraced to the Circumference of the

Driving Pulley.

Value of Coefficient C.

Leather Belts.

Cords on Wooden Sheaves.

On Wood Drums.

On Iron Pulleys.

Rough.

Polished.

•2

1.8

1.4

1.9

1.5

•3

2.4

1.7

2.6

1.9

•4

3.3

2.

8.5

2.3

•5

4.4

2.4

4.8

2.8

•6

5.9

2.9

6.6

3.5

•7

7.9

8.4

9.

4.2

C = the ratio of the resistance of a drum or pulley to flipping a belt or cord when the resistance of the belt or cord upon the under or slack side is known.

Example

What is the stress a belt is capable of transmitting when the arc embraced upon the surface of the driving and wooden drums is .4 of its circumference, and the power or tension of the belt is 200 lbs.?

3.3 X 200 = 660 lbs.