Transient EHL Effects in Starved Ball Bearings

The independent variables used in most calculations for EHL film thickness in ball bearings involve lubricant properties, contact elasticity, load, and bearing kinematics. The calculations are for steady state, and they give a time-constant film thickness. Experiments have shown four distinct processes in starved ball bearings which are explainable assuming a time-varying film thickness. This contribution describes these four processes as well as another transient EHL effect which does not involve the thickness of the film. A simple model, based on experimental considerations, allows direct calculation of several of the thickness transients.