Abstract: Each of several types of speed changers comprise a pair of generally dish-shaped housing sections releasably secured in confronting relation around their peripheries with a high speed shaft journaled in an axial bore of one section, and a low speed shaft or hub journaled in the other section coaxially of the high speed shaft. At least one two-step cluster gear is secured to the inner end of the high speed shaft and has a pinion section drivingly engaged with a set (three) of two-step planetary cluster gears that are rotatably mounted on three shafts that are fixed at opposite ends in a pair of circular carrier plates which also are journaled coaxially in the housing sections to be rotatable therein in unison. The pinion sections of the planetary cluster gears are drivingly engaged with the teeth of an internal sun gear secured in the housing coaxially thereof.

Abstract: This gear unit connects coaxial drive and driven shafts. It comprises two integral coaxial externally-toothed cluster gears which mesh, respectively, with two coaxial internal gears, one of which is secured in the fixed housing of the unit and the other of which is fixed to one of the shafts. The other shaft has a crank secured to it which drives a pin that is coaxial with the cluster gears but eccentric of the internal gears. The pin has a cylindrical bearing portion engaging a cylindrical thrust member carried by the internal gear which is fixed to one of the shafts. This thrust member is coaxial with the shafts.