Torque loss in thrust ball bearings lubricated with wind turbine gear oils at constant temperature

Author-Highlights•Six wind turbine gear oils were selected. Density and viscosities were measured.•Frictional behaviour of a thrust ball bearing (51107).•Tests were performed in a modified Four-Ball Machine between 75 and 1200 rpm.•Friction torque is presented for different loads at constant temperature (80 °C).•Rolling and sliding friction torques were determined.

Six fully formulated wind turbine gear oils with the same viscosity grade and different formulations were selected and their physical properties were determined.Thrust ball bearing friction torque tests were performed on a modified Four-Ball Machine at a constant temperature of 80 °C under the following operating conditions: speed between 75 and 1200 rpm and two loads (700 N and 7000 N).The experimental results showed that wind turbine gear oil formulation has a significant influence on rolling bearing friction torque.