Apparatus for inspecting a gear

Abstract

A master gear for measuring, in a parallel axis gear measuring apparatus, tooth profile, tooth pitch, and tooth thickness of a work gear. The master gear has a plurality of adjacent teeth separated by a tooth spacing that varies as a repeatable sequence of spacings, wherein the master gear contacts only a single tooth of the work gear during measurement of work gear tooth profile and tooth thickness. The master gear contacts only two teeth of the work gear during a transition between measurement of tooth profile of individual teeth of the work gear, wherein tooth pitch is measured during the transition. The master gear also has transverse operating pressure angle dependent on a transverse pressure angle at an outer diameter of the work gear, a transverse pressure angle at a form diameter of the work gear, a transverse pressure angle at a pitch diameter of the work gear, a transverse tooth thickness at a pitch diameter of the work gear, and a pitch diameter of the work gear. In one embodiment, the master gear has helical teeth having a tooth spacing and a gear width dependant on a contact ratio of the work gear. In another embodiment, the master gear has spur teeth for measuring a work gear having spur teeth. The master gear having spur teeth is defined by parameters relating to a pressure angle of an imaginary outer diameter of the work gear and a pressure angle of an imaginary form diameter of the work gear.