Influence of the Oil Churning, the Bearing and the Tooth Friction Losses on the Efficiency of Planetary Gears

The efficiency of a planetary gear depends on many factors: mainly on the tooth- and bearing friction losses, but beside them, in certain circumstances, also the oil churning losses have to be taken into consideration. This theoretical investigation was made to determine the oil churning, the bearing and the tooth friction losses of planetary gears and evaluate the influence of these types of friction losses on their efficiency. Optimization of the design of the planetary gear drives can result the best parameters leading to their highest efficiency even in the case of compound planetary gears.