Abstract
This paper describes a study on the effect of lubricants on the rolling friction produced when a hard steel ball rolls between two parallel flat plates. The main results obtained are as follows. (1) When the rolling contact surfaces are lubricated with a small amount of the oil, the lubricants surely decrease the adhesion acting on the contact surfaces, so that according to the oil film strength, the lubricants reduce the magnitude of the rolling friction which is due to the separating resistance on the contact surfaces. (2) But when the contact surfaces are lubricated with excessive quantities of oil, because of the viscosity and the surface tension, the lubricants does not reduce the magnitude of the rolling resistance. (3) After all when the two effects are compensatory, the rolling frictions remain nearly constant for both lubricated and unlubricated surfaces.
