Effects of planet spanwise engagement on the instantaneous efficiency of compound geared rotary actuators

The instantaneous efficiency characteristics of actuators with normal compound planet gears were investigated in a previous paper (Wang et al., 2011). The actuator's reacting forces on the planets are either symmetric or asymmetric and spanwise distances between meshes on the compound planet gears will not affect the efficiency. The cantilevered actuator, on the other hand, with asymmetric planet gears is studied in another paper (Wang et al., 2015) and spanwise distances between meshes on the compound planet gears are key factors in the efficiency calculation. In this paper, the derivations of the instantaneous efficiency for both types are discussed and the effect of spanwise distances between meshes on efficiency is explored.