The effect of running-in on the efficiency of superfinished gears

•Surface roughness of superfinished gears did not change by a running-in procedure.•Superfinished gears where more robust than ground gears.•Superfinished gears yielded a lower efficiency in at low speeds.

Reduced gear contact losses are necessary to keep operating temperatures, as well as fuel consumption low. In this work, an FZG gear test rig was used to investigate the effect of running-in on superfinished gears with respect to efficiency. This was compared to ground gears where a higher contact pressure yielded higher efficiency. No difference was found between the two running-in procedures when analysing superfinished gears. The effect of running-in on gears decreased when the initial surface roughness was reduced, which initially had an Ra, Rz and Rpk value of 0.08, 0.75 and 0.08 μm, respectively. Superfinished gears showed an overall higher efficiency; however, a distinctly lower efficiency was present below 2 m/s when compared to ground gears.