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The paper covers the solutions to the following problems: (1) Setting up a mathematical model for the involute helical gears; (2) Computer simulation of the conditions of meshing and bearing contact; (3) Investigation of the sensitivity of gears to the errors of manufacturing and assembly; and (4) Stress analysis of the gears. In this paper, the theory of gearing and the concept of differential geometry have been applied to deal with the relations of two mating helical gears and their bearing contact. Computer program for tooth contact analysis (T.C.A.) has been developed for the gears. The T.C.A. computer program makes it possible to simulate gear meshing and bearing contact, and to investigate the influence of gear misalignment on kinematic errors. A method of compensation for the dislocation of bearing contact and for kinematic errors induced by errors of manufacturing and assembly has been proposed. Four numerical examples have also been presented to illustrate the influence of the above-mentioned errors and the method of compensation for the dislocation of bearing contact. Based on the derived mathematical model, an automatic mesh generating computer program—AMG has been developed to define the geometry of the gears and to divide the gear tooth into elements as well as to generate nodal points automatically. The results of T.C.A. provide the locations and directions of the applied loadings for the finite element method (F.E.M.) stress analysis.

Pitch curves of a conjugate noncircular gear pair are derived based on kinematic considerations. A method for considering the inverse mechanism relationship and the equation of meshing, is proposed here to derive a complete mathematical model of noncircular gears manufactured with involute-shaped shaper-cutters. The proposed method is similar to the contact line method and the envelope method, but is easier to apply to the determination of tooth profiles. A computer program is developed for generation the tooth profile with backlashes. Undercutting analysis is also investigated by considering the relative velocity and equation of meshing. Finally, modified elliptical gears are presented to illustrate the tooth profile generation when the proposed mathematical model is applied, and to investigate the phenomenon of tooth undercutting.

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