A new kind of gear measurement technique

This method of gear error measurement is based on the traditional gear single-flank measurement, but uses a special master gear with three kinds of measuring tooth and a transmission tooth. The first kind of measurement tooth has a projective involute used as a reference. When engaged in mesh with the tooth of the workpiece, the deviation of transmission reflects the involute profile error of the workpiece. When a projective helix on the second measurement tooth is meshed with the workpiece the lead error can be obtained. Because the third kind of measurement tooth is the same as that used by a single-flank tester, the tangential composite error can be obtained. The transmission tooth is used to make the contact ratio less than one. When the new master gear is meshed with the workpiece for several turns the pitch error of the latter can be measured. (Abstract quotes from original text)