Tooth contact analysis of spur and helical gears with end relief profiles

The meshing process of two gears is altered by elastic deformations of the machine parts involved in the power transmission chain. The edge effect appears and some additional manufacturing procedures are necessary to be done. The paper presents a computerized program used to establish the suitable value for the profile correction according to the particular running parameters as torques and misalignments. Semi-analytical methods were used to obtain the elastic state, developed during the meshing process, around the concentrated contact of pinion and gear. For spur gears the separation is possible to be obtained analytically, while for helical gears a numerical algorithm has been developed to obtain the matrix of separations. The two approaches were validated and some numerical results regarding the 2D and 3D pressures distributions as well as the contact areas, are presented. For operating condition without misalignment, the lead modification by end relief could led to a very favourable, quasi-Hertzian, pressures distribution. The presence even of a quite small value of misalignment changes the quasi-Hertzian distribution to a skewed one with detrimental effect on gear's life.