A contact trajectory model of four-point contact ball bearings under dynamic operating condition is presented by means of multi-body dynamics and multi-freedom kinematic analysis. The model is employed to investigate the matching relationship between the operating condition and the number of contact points on a ball in a typical four-point contact ball bearing. The number of contact points on the ball is described by the contact trajectories along the raceways due to the ball interacting with the inner and outer raceways during operation. It is found that the number of contact points on the ball surface in a four-point contact ball bearing changes as the external load and the inner race velocities change. The study also shows that two-point contact condition will take place on the ball surface and the raceways when a large axial load and a small rotational speed are applied to the bearing. The results can provide useful guidance for the selection of working conditions to improve the contact behaviour and service life of four-point ball bearings.

Four-point contact ball bearings,Contact trajectory,Contact behavior,Rotational speed,Load