Page 248 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

230 Major Process Equipment Maintenance and Repair

Spur gear
4

I I
Goth thickness A L fircufar pitch
A
L fircufar pitch
Goth
thickness
Spur rack
Figure 6-6. Spur gear and rack terminology.

Gear Terminology

Figures 6-6, 6-7, 6-8, and 6-9 illustrate the standard terminology often
referred to in the world of gearing. Every gear user should be familiar with
at least some of the terms represented in these figures. The following is a
brief listing of the definitions of some of the more commonly used gearing
terns:
1. Addendum--The radial distance between the pitch circle and the
addendum circle.
2. Addendum Circle-The circle which bounds the outer ends of the
teeth. Usually referred to as outside diameter.
3. Angle of Action-The angle through which the gear turns from
the tim a particular pair of teeth come into contact until they go
out of contact.