Abstract :
ELECTRIC motors and other types of prime movers rotate at much higher speeds than do the majority of driven machines and therefore some means of speed reduction is necessary. One of the most important and most efficient of methods is gearing, which satisfies the fundamental requirements of compactness and high mechanical efficiency. With helical gears mounted on anti-friction bearings and running in oil, efficiencies of 98 per cent for single-reduction gear drives and 96 per cent for double-reduction drives may be attained. Initial cost is always important in the purchase of power-transmission equipment, and surveys indicate that in the majority of applications the gear transmissions can be purchased for a lower initial cost than can other types of drives. This is also true for slow-speed motors which would form an alternate for the high-speed motor and some form of speed reduction.