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

•Six wind turbine gear oils were selected. Density and viscosities were measured.•Frictional behaviour of a cylindrical roller thrust bearing (81107).•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.Cylindrical roller thrust 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.