Efficiency of a gearbox lubricated with wind turbine gear oils

•Four wind turbine gear oils were selected. Density and viscosities were measured.•Efficiency tests were conducted on a gearbox at low speeds and high torques.•A power loss model simulating all the relevant power loss components was implemented.

In this study a two stage multiplying gearbox with helical gears and four fully formulated wind turbine gear oils were tested, on a back-to-back gearbox test rig with recirculating power, at low input speeds (100–500 rpm) and high input torques (500–1000 Nm). The gearbox oil sump temperature was set free.A numeric power loss model simulating all the relevant power loss mechanisms was implemented, aiming to evaluate the relative influence of each power loss component.The experimental results have shown that each wind turbine gear oil formulation generated different power loss resulting in distinct stabilized operating temperatures.