Solution of the failure of the bearings in a planetary gear train

The fracture of the retainer leads to the failure of the needle rolling bearings in a planetary gear train of a planetary gearbox. In order to solve this engineering problem, the kinematics and kinetics of the failed needle rolling bearings is analyzed with the analytical model and the numerical model. A simple mathematical model is pointed out to analyze the dynamic load of a needle rolling element in the failed bearings. The assembling position of the small sun gear is also found to influence the performance of the needle rolling bearings significantly and therefore a best scheme for modifying the structure of the planetary gearbox is pointed out based on the multi-object optimization theory to reduce the bearing load heavily. Based on the calculated work, a systematic method of choosing the proper bearings for planetary gearbox can be concluded.