Abstract
The tooth surfaces of conjugate gears are slightly modified in some cases in order to provide the insensitiveness to manufacturing errors and misalignments. When the tooth surfaces of the conjugate gears are modified, the line contact in meshing of gear teeth turns into a point contact. In this case, the progressive direction of contact point on the gear tooth surface concerning with the meshing progress has an influence on the performance of the gears. The progressive direction of tooth meshing has not been almost considered in gear kinematics so far, so that gear manufacturers could not get the standard tooth contact pattern on the tooth surface, and gear engineers could not know the real meaning of the tooth meshing. In this paper, the meshing of gear teeth is discussed and the progressive direction of tooth meshing is made clear based on gear kinematics. As examples of hypoid and worm gears, slide lines and contact lines are calculated numerically. The results show that the progressive direction of tooth meshing is the direction of the relative velocity between meshing gears. We understand loosely the tooth meshing which is the most fundamental phenomenon in the gears. The tooth meshing means the sliding contact of a pair of slide lines.
