Epicyclic Gear Trains
In its simplest form, three pairs of external non-circular gears rotate in mesh with two identical non-circular internal gears, in a way that resembles that of two epicyclic gear trains. That’s why the internal gears are called ring gears (RG) and the external gears are called planet gears (PG), although there is no sun gear in the present arrangement.
Each pair of planet gears rotates in unison and keeps a fixed relative position with respect to the other pairs by means of a planet carrier (PC). One ring gear is fixed to the stator and the other one is fixed to the rotor. As the planet carrier rotates, it forces in turn the planet gears to rotate in mesh with the ring gears and produces their relative motion.
Although the gear oscillator substitutes for the crankshaft, it works in quite a different way. In fact, the operation of this mechanism resembles much more that of a set of pulleys.