The velocity of the belt is
| circumference in feet | × | revolutions | = | feet per minute | ||
| 16 | ||||||
| × | .1416 | × | 1,000 | = | 4,188. | |
| 12 | ||||||
Horse power transmitted per inch width of double belt at 4,188 feet speed
| 4,188 | ||||
| 2 | × | = | 8.38. | |
| 1,000 |
Fig. 1,384.—Fort Wayne revolving field belt driven alternator. It is designed for belted exciter, having a shaft extension at the collector ring end for exciter driving pulley.
Width of double belt for 50 horse power
50 ÷ 8.38 = 5.97, say 6 inch.
Ques. What are the advantages of chain drive?