Ease-Off and Application in Tooth Contact Analysis for Face-Milled and Face-Hobbed Spiral Bevel and Hypoid Gears

The ease-off concept was introduced to describe the mismatch, a deviation between conjugation and non-conjugation, between two tooth surfaces from a pair of mating bevel gears in contact. However, a complete mathematical description of ease-off and the algorithm of computation were not found. The application of ease-off concept in tooth contact analysis (TCA) allows for a numerical determination of contact patterns and transmission errors of highly conformable contact or almost conjugate contact of tooth surfaces. The paper analytically describes a generalized theory of ease-off and its application in tooth contact analysis of both face-milled and face-hobbed spiral bevel and hypoid gears with complex tooth surface modifications. The implementation of the ease-off algorithm applied to the tooth contact analysis is illustrated with two examples of, respectively, a face-milled gear drive and a face-hobbed hypoid gear drive.