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# pitch circle

noun, Machinery.
1.
an imaginary circle within the profiles of the teeth of a gear, such that it rotates against a similar circle rotating at the same rate on a meshing gear.
Also called pitch line.
Origin of pitch circle
1810-1820
First recorded in 1810-20
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
Cite This Source
Examples from the Web for pitch circle
Historical Examples
• AddendaTips of the teeth of a wheel beyond the pitch circle.

Harry Chase Brearley
• We may also say that the pitch circle is the edge of the pitch surface.

David Allan Low
• By the diameter of a wheel is meant the diameter of its pitch circle.

David Allan Low
• And to pencil in the teeth these circles must be fully drawn, as in Figure 234, in which P P is the pitch circle.

Joshua Rose
• Where these divisions intersect the pitch circle are the centres from which all the teeth curves may be drawn.

Joshua Rose
• The circumference of the pitch circle divided by the arc pitch gives the number of teeth in the wheel.

• The arc pitch multiplied by the number of teeth in the wheel gives the circumference of the pitch circle.

• The depth below pitch line or the length of flank is, therefore, the distance between the pitch circle and the base circle.

• The amount of error thus induced diminishes as the diameter of the pitch circle of the cutter is increased.

• The flank of each wheel is struck with a tracing point, thus attached to the pitch circle of the other wheel.

British Dictionary definitions for pitch circle

## pitch circle

noun
1.
an imaginary circle passing through the teeth of a gearwheel, concentric with the gearwheel, and having a radius that would enable it to be in contact with a similar circle around a mating gearwheel
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition