LAUSR

Abstract Frictional torque jump is present at ball-bearing-like specimens in grease lubrications, it is formed to be bearing instabilities at a time dependent on bearingʹs groove factor, raceway's roughness. Intrinsic mode functions for vibrations are identified as the results of ball-spacer tribo contacts through FFT analyses. By the facts of having the highest wear and seizures, spacer instability is assumed to be related to these jumps. The instability model is developed for ball-spacer interactions considering the partition of frictional heat and thermal effects on linear expansion of dominant side. The inception time and its friction coefficient predicted by the present model are close to those shown in experiments. This model provides an efficient formula to evaluate the effects on inception time.