Page 243 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Chapter 6
Power Transmission Gears*

Gear drives have always been a necessary part of industry. Conse-
quently, since industrial personnel need to have a good working knowl-
edge of gearing, some of the basic principles of operation, installation,
lubrication, maintenance, troubleshooting, and repair of power transmis-
sion gears are outlined in this chapter.
Four basic types of gears comprise most of the heavy duty industrial
gearing in use today. Therefore, due to time and space limitations, the
main gear types covered here are the most common ones used to transmit
high torques: single and double helical, spiral bevel, and spur gearing.
However, most of the information presented here can be applied to other
gear types with slight modification.

Introduction

Gears are among man’s oldest and best recognized mechanical devices.
They create the impression of positive action-coordinated, interlocked,
precise effort to secure a desired result. Gears were once primarily used
for navigation, timekeeping, grinding, etc. Now, the automobile trans-
mission is probably the most common use of gearing that the everyday
citizen sees.
Gears are machine elements that transmit motion by means of success-
fully engaging teeth. Of two gears that run together, the one with the
larger number of teeth is called the “gear.” The “pinion” is the gear with

* By James R. Partridge, Chief Engineer, Gear Division, Lufkin Industries, Inc.,
Lufkin, Texas. Reprinted by permission.

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