Gear tooth geometry is determined primarily by pitch, depth, and pressure angle. Pitch: Standard pitches are usually whole numbers when measured as diametral pitch P, the ratio of the number of ...

Gear hobs (GH) used to produce spur and helical gears have trapezoidal profiles with different angles — 14.5 degrees, 20 degrees, 25 degrees — the same as profiles of standard basic racks. According ...

Parameters such as diametral pitch or module, profile angle, addendum, whole depth, and fillet-radius proportions define the cutting edge of the hob, called the generating gear rack.

This article was originally published with the title “Diametral and Circular Pitch” in SA Supplements Vol. 61 No. 1588supp (June 1906), p. 25437 doi:10.1038 ...