Measuring Friction Coefficient of the High Speed Pivot Bearing in Oil-bath Lubrication by a Varying Load Method

A varying load method was presented to measure the friction coefficient of the high speed pivot bearing in oil-bath lubrication. The friction coefficient of the pivot bearing running at different speeds was measured on the test apparatus. The experimental results showed that the friction coefficients of the pivot bearing samples diverged greatly at the same test speed, which was due to the randomness and complexity of the boundary lubrication of the pivot-jewel bearing in oil-bath. However, all of the friction coefficients became smaller when the running speed increased for every pivot bearing sample,and average measured values were between 0.09 and 0.05. The decrease of the friction coefficient with the increasing speed indicated that the hydro-dynamic effect in the boundary lubrication became strong and the thin-film lubrication cut down the probability of surface contact between the pivot and the jewel. The reliability of the measurement method was analyzed by calculating the energy loss from bearing friction. The friction coefficients of a spiral groove oil film bearing used in the flywheel support system were between 0.017 ~ 0.014 by the same test method