Abstract: Anti-backlash gear can improve the transmission precision via eliminating or controlling the backlash. It is very important to make a study of the dynamic characteristics of anti-backlash mechanism. The law of periodic variation of meshing points is analyzed emphatically in anti-backlash mechanism with the contact ratio . Single or double tooth meshing states of two gear pairs and the transform arithmetic in positive and reversal rotation based on symmetry at anytime are determined, insuring continuity of calculator in reversal rotation and making the further studies on swept resonance characteristic easier. Based on this, the synthesis meshing stiffness model of anti-backlash mechanism is built, including the calculation formula of meshing stiffness based on Hertz contact theory and FE calculation results. The influence of torsional spring stiffness and variations of all gear parameters on synthesis meshing stiffness is analyzed using numerical calculation, and the results show that under the condition of no gear teeth disengaging, anti-backlash mechanism not only can eliminate the backlash, but also can increase the synthesis meshing stiffness comparing with the meshing stiffness of the ordinary gear pair, and by optimizing gear parameters, the synthesis meshing stiffness can be increased much more.

Key words: Anti-backlash, Double-gear, Dynamic characteristics, Meshing point, Symmetry, Time-varying meshing stiffness