An experimental investigation of spin power losses of a planetary gear set

•This experimental study investigates spin power losses of planetary gear sets.•Tests were performed to isolate and rank-order spin loss components.•Viscous the planet bearing power loss is the most dominant loss component.•Gear mesh pumping losses contribute to the spin power losses significantly.

This experimental study investigates the contributions of the key components of load-independent (spin) power losses of planetary (epicyclic) gear sets. A dedicated test set-up is developed to operate a planetary gear set under unloaded conditions in various hardware configurations within a wide range of speed. Torque provided to the gear set is measured as the spin torque loss. A test matrix is executed specifically to measure total spin loss of the gear set as well as the contributions of its main components, namely drag loss of the sun gear, drag loss of the carrier assembly, pocketing losses at the sun–planet and ring–planet meshes, viscous planet bearing losses, and planet bearing losses due to centrifugal forces caused by the rotation of the carrier. Variations of the same gear set are tested and results from these tests are compared to estimate and rank order the contributions of these components of power loss. Impact of the rotational speed and oil temperature levels on each component is also quantified.