The spacing between adjacent teeth measured around the pitch circle, equal to pi times module, or pi divided by diametral pitch. Tooth thickness plus space width add up to one circular pitch, so nominal tooth thickness is half of it before backlash allowance is removed. Racks and large cast gears are sometimes specified directly by circular pitch.
Circular pitch on that cast wheel is an inch and a half even, so it's a CP pattern, don't go hunting for a DP cutter.
Also heard as
- CP
- transverse circular pitch
Related terms
Module
The metric measure of gear tooth size: pitch diameter in millimeters divided by the number of teeth.
Diametral pitch
The inch measure of gear tooth size: number of teeth per inch of pitch diameter, larger number for finer teeth.
Tooth thickness
How thick a gear tooth is along the pitch circle, the dimension that is thinned to create backlash.
Pitch deviation
Errors in tooth spacing, either from one tooth to the next or accumulated around the gear.