Effect of preload on ball-raceway contact state and fatigue life of angular contact ball bearing

•The criterion of ball-raceway separation is given.•A dynamic model for ball bearing under an arbitrary preload is presented.•The effects of loads, preload and speed on bearing contact state are discussed.•The relation between the preload and fatigue life is discussed.•An optimum preload determined by bearing life can be obtained for given loads.

The performance of angular contact ball bearing is greatly affected by the preload. In the present research, by analyzing the state of ball-raceway contact, a quasi-dynamic model is proposed to study the load distribution of ball bearing under arbitrary preloads. The new model is then used to study the influences of external loads, rotating speed and preload on ball-raceway contact state. Based on this, the fatigue life of ball bearing under running condition is calculated. The results show that a proper preload improves the load distribution and extends the fatigue life of ball bearings. For any given load and rotating speed, an optimum preload, estimated through the bearing life, can be obtained.