Standard Handbook of Plant Engineering, Third Edition
Packed with tables, formulas, charts, graphs, and checklists, this guide offers you the cutting-edge information you need to keep your plant operating at peak efficiency and profitability.
TABLE OF CONTENTS Standard Handbook of Plant Engineering, Third Edition
Chapter 5.4: Mechanical Equipment: Gearing and Enclosed Gear Drives
William A. Bradley III
American Gear Manufacturers Association (AGMA)
Alexandria, Virginia
GEARS AND GEAR DRIVES
The major uses of gears and gear drives are to transmit power, with reduction or increase of speed and multiplication of torque. In addition, gears are used to transmit rotary motion from one shaft to another in a uniform manner, and for positioning. Gear drives are usually classified as reducers, increasers, high-speed drives, or drives for the accurate positioning of loads.
Gear Drive Types
Speed Reducer. Economically, it is normally better to use a small, high-speed prime mover and gear-reducer combination than a larger, low-speed power source.
Speed Increaser. In some instances, it is impractical to operate a prime mover at a speed high enough to suit requirements of the driven equipment. For such applications, gears may be used as a speed increaser.
Positioning. It may be necessary to index or position objects with a shaft that does not normally make a complete revolution. The relative load to drive size may make it practical to use gearing or gear drives.
Shaft Orientation. Gear drives are furnished with various shaft orientations and speed ratios. Some common arrangements that are available include: in-line, parallel shaft, and right angle. Miter gears (1:1-ratio bevel gears), for example, serve the specific purpose of providing a 90 shaft orientation. Other angles can be supplied by specially designed gears of several types.
Gear Types
The most common types of gears are illustrated in Figs.
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