Friction Torque of Four-Point Contact Ball Bearings Based on Dynamic Model

A friction torque model is proposed utilizing a three-dimensional transient dynamic approach for four-point contact ball bearings. A typical mix-lubrication traction model is applied to calculate the traction force on the contact surface between ball and raceways by means of the comprehensive surface friction shear stress model. Then the friction torque model is validated by the experiment results. After that, the model is used to investigate the friction torque under various operating conditions. It is found that the multi-point contact state of the four-point contact ball bearing leads to increased frictional losses within the bearing. The friction torque reaches its lowest value as the increasing of inner ring rotational speed and then increases sharply along with the transition of contact state.