Friction models for grease lubricated ball-race contacts

Abstract

In this paper the authors theoretically investigated the influence of the hydrodynamic rolling friction forces in greased ball-race contacts at low loads. Two IVR-EHL transitions equations for hydrodynamic rolling friction forces have been applied to the ball-race contacts in a modified thrust ball bearing by using three types of greases having base oil viscosities between 40 mm2/s and 1000 mm2/s. Based on the total friction torque analytically estimated and experimentally determined has been evidenced the influence of the hydrodynamic rolling friction force on the total friction torque as the most important parameter for both proposed transition equations. The theoretical values of the total friction torque have been experimentally validated. The experiments was realized with a modified tree ball thrust bearing, without cage in a range of speed between 60 rpm and 400 rpm and for a normal load of 1.422 N for each ball.