pitch circle

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pitch circle

[′pich ‚sər·kəl]
(design engineering)
In toothed gears, an imaginary circle concentric with the gear axis which is defined at the thickest point on the teeth and along which the tooth pitch is measured.
References in periodicals archive ?
D3, D4, etc = diameters of pitch circles of planetary gears;
Draw a line ab tangent to the pitch circle of the driver, if it is a gear, and at the point a where the center line of the train arm intersects this pitch circle.
If the driver is a gear (as in the illustration) it will usually be found that point a on the pitch circle of the driver coincides with a point on the pitch circle of a planet gear which either itself engages the fixed gear in the train or is keyed to the same shaft as another planet gear which engages the fixed gear.