Torque loss of type C40 FZG gears lubricated with wind turbine gear oils

Five fully formulated wind turbine gear oils were characterised. The gear oils have 320 ISO VG grade and different formulations: ester, mineral, PAO, PAG and mineral+PAMA. A back-to-back FZG test machine, with re-circulating power, was used and a torque-cell was included on the test rig in order to measure the torque loss. Eight thermocouples were included to monitor the temperatures in different locations of the test rig. Tests at 1.13, 2.26 and 6.79m/s were performed for different FZG load stages: K1, K5, K7 and K9. Both gearboxes were jet-lubricated with an oil flow of 3l/min. The input flow temperature was kept almost constant (80 ±1°C). Friction generated between the meshing teeth, shaft seals and rolling bearing losses was predicted. •Five wind turbine gear oils were selected. Density and viscosities were measured.•A back-to-back FZG machine was used and a torque cell included to measure the torque loss.•Torque loss was measured for a type C40 FZG gears.•Tests at 1.13, 2.26 and 6.79 m/s were performed at K1, K5, K7 and K9 load stages.•A torque loss model was developed and validated.