Losses in Thrust Ball Bearings Lubricated with Axle Gear Oils

This work provide more new knowledge about rolling bearings lubricated with axle gear oils. Extensive tests were performed and a considerable amount of experimental results of power loss in rolling bearings, difficult to find in literature, were obtained. Five fully formulated axle gear oils with different base oil, viscosity and different formulations and additive packages were selected. Their chemical and physical properties were measured. Thrust ball bearings lubricated with axle gear oils were tested using a modified Four-Ball Machine where the four-ball arrangement was replaced by a rolling bearing assembly. These tests were performed under a constant temperature of 70 \(^{\circ }\)C and under the following operating conditions: speed between 75 and 1200 rpm and two axial loads (4000 N and 7000 N). The rolling bearing friction torque was measured and the effect of speed, temperature and axial load have been evaluated. Based on experimental results, a rolling bearing torque loss model was calibrated using SKF model for ball contacts. The model allows a better understanding of the behaviour of the rolling bearing geometries and of the influence of oil formulation on rolling bearing friction torque. The rolling bearing power loss model will be relevant for the global axle differential power loss model predictions.