Knowledge Bank

Planetary gear sets experience two forms of power losses: load-dependent (mechanical) and load-independent (spin) losses. As pitch-line velocities increase, spin losses often become the dominant source of loss in high-speed gear systems, leading to lower efficiency and fuel economy. This also causes higher operating temperatures, which can affect the durability of the gear set adversely. This research focuses on experimentally measuring various components of a planetary gear set spin loss at high pitch-line velocities. A test setup to measure spin power losses from lubrication sprayed to the side of a gear at the interface between a planet gear and the supporting journal bearing is designed. A methodology to extract component losses of planetary gear set spin power loss including loss due to the journal lubrication is adapted and applied to the experimental set-up such that these losses can be quantified across a range of speeds. The measured component losses are combined to estimate the total spin power loss of an entire planetary gear set with an arbitrary number of planet gears.