| F = | 10 × 100 | HP = | 25,000 × 500 | = | 378 horse-power. |
| 2 | 33,000 |
Nystrom gives this rule:—HP = V × F⁄₅₅₀. V = velocity of belt in feet per second. F = force in pounds transmitted by belt.
The first rule gives good practical results where there is no great inequality in the diameter of the pulleys.
Double Belts transmit 1½ times as much as single belts.
Splicing Belts.
| Width of Belts | 1 | 2 | 3 | 3 to 6 | 6 to 8 | above 8 in. |
| Lap in inches | 2 | 4½ | 5½ | 6 | 8 | 10 |
Rules for Double Leather Belting.
A = covered area of driven pulley in square inches.
V = speed of belt in feet per minute.
H = indicated horse-power.