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Involute Teeth.—For tabular values look opposite “Pinion,” under proper number of teeth, for each wheel.

The principles involved in the construction of a rack to work correctly with a wheel or pinion, having involute teeth, are as in Fig.

From this it becomes apparent that involute teeth being always thicker at the root than at the pitch line, and the spaces being, therefore, narrower at the root, may be cut with these cutters, no matter what the diameter of the base circle of the involute.

Involute teeth.—These are teeth having their whole operative surfaces formed of one continuous involute curve.

A method commonly employed in practice to strike the curves of involute teeth, is as follows:— Fig.