Journal-Bearing Friction in the Region of Thin-Film Lubrication
AUTOMOTIVE engineers, who have to deal with high-speed high-load journal bearings and are confronted with fear of the consequences of “ragged-edge” thin-film lubrication, will find much of interest and value in this report. It covers the information obtained and conclusions reached as a result of the extension of research into the region of thin-film lubrication, in which little investigation has heretofore been made.
Tests made in a four-bearing machine, using both high-tin babbitt and high-lead bronze bearings and operated on lubricants of various viscosities over a wide range of speed and load, showed conclusively that the coefficient of friction depends directly upon the viscosity even in the thin-film region. They indicated defnitely that the friction coefficient is more likely a function of ZN/√P than of ZN/P. It was found also to depend upon the metal of which the bearing is constructed, whereas, in the region of thick-film lubrication, the coefficient of friction is independent of the composition of the bearing metal.