Planetary Transmission

An assembly of meshed gears consisting of a central or sun gear, a coaxial internal or ring gear, and one or more intermediate pinions supported on a revolving carrier. Sometimes the term planetary gear train is used broadly as a synonym for epicyclic gear train, or narrowly to indicate that the ring gear is the fixed member. In a simple planetary gear train the pinions mesh simultaneously with the two coaxial gears (see illustration). With the central gear fixed, a pinion rotates about it as a planet rotates about its sun, and the gears are named accordingly: the central gear is the sun, and the pinions are the planets.

This is a compact, 'single' stage planetary gearset where the output is derived from a second ring gear varying a few teeth from the primary.

With the initial model of 18 sun teeth, 60 ring teeth, and 3 planets, this resulted in a 'single' stage gear reduction of -82.33:1.

A regular planetary gearset of this size would have a reduction ratio of 4.33:1.

That is a whole lot of torque in a small package.

At Nominal Voltage