This standard applies to gearmotors, shaft mounted and screw conveyor drives defined as enclosed gear drives having spur or helical gearing, alone or in combination with straight bevel, spiral bevel or worm gearing. The purpose of this standard is to define a rating and selection practice for these gear drives. Users of this standard are expected to have had experience in the field of gearing and mechanical drive systems.

Gearmotors

A gearmotor is defined as an enclosed gear drive in combination with an electric motor of 1/8 HP or larger, the frame of one supporting the other, with the motor shaft common or directly coupled to the input shaft and parallel, concentric, or at a right angle to the output shaft. The output shaft may be either solid or hollow.

Shaft mounted drives

A shaft mounted drive is defined as a gear drive with a specific nominal output shaft bore size in accordance with this standard to a maximum of 6.5 inches.

Screw conveyor drives

A screw conveyor drive is defined as a gear drive with specific mounting and drive shaft dimensions in accordance with this standard.

Limitations

This standard is applicable to gear drives having single or multiple stage gearing with pitch line velocities not exceeding 7000 ft/min for spur and helical gearing and 6000 ft/min for straight bevel, spiral bevel and wormgearing, and component speeds not exceeding 4500 rpm for helical, spur, straight bevel and spiral bevel gearing and 3600 rpm for wormgearing. Wormgearing operating at sliding velocities greater than 2000 ft/min may require special lubricants, pressurized systems or both.

Exceptions

This standard does not cover epicyclic gear drives. This standard does not cover the rating of spur, helical or bevel gears due to wear or scuffing. The design and rating of the electric motor is beyond the scope of this standard.