Gearing for high speed motors

In industry, machinery operates at greatly different speeds. A large cement mill or steel converter runs at fractions of a revolution per minute, while centrifugal compressors operate at 5000 to 20,000 RPM. In between these extremes comes the large majority of machines running at 10 to 1000 RPM. The absorbed powers vary as widely, from fractions of a kilowatt to many megawatts in large conveyors and process plant. Gearboxes are used to match the operating speed of the prime mover-engine or motor-to the requirements of the driven machine. They are used for both speed increasing drives-for example centrifugal compressors, and for speed decreasing drives for medium and slow speed machinery. Gearboxes come in all sizes and ratios, transmitting a few watts in power tools to 50 or 60 MW in ship propulsion and gas turbine driven generators. This paper outlines the performance limits of high power gearing, for use with high-speed motors for driving low-speed machinery