A mechanical speed changer comprising in combination :
- (a) frame;
- (b) a power output member of generally axisymmetric construction rotatably supported by the frame;
- (c) a shaft disposed in line with the power output member and rotatably supported by the frame;
- said shaft including a first and second eccentric section disposed in two generally opposing eccentric arrangements;
- (d) a first rotary member with a first set of meshing elements rotatably mounted on said first eccentric section of the shaft, wherein said first set of meshing elements is disposed in a concentric arrangement about the central axis of said first eccentric section of the shaft, and a plurality of circular holes with central axis parallel to the shaft disposed on a circle concentric to the central axis of said first eccentric section of the shaft;
- (e) a second rotary member with a second set of meshing elements rotatably mounted on said second eccentric section of the shaft, wherein said second set of meshing elements is disposed in a concentric arrangement about the central axis of said second eccentric section of the shaft, and a plurality of circular holes with central axis parallel to the shaft disposed on a circle concentric to the central axis of said second eccentric section of the shaft;
- wherein, said first and second sets of meshing elements engage each other over a portion of said concentric arrangement;
- (f) a plurality of circular cylindrical posts disposed on a circle concentric to the central axis of the shaft and rigidly affixed to a member nonrotatably secured to the power output member and respectively engaging the plurality of circular holes included in one of the first and second rotary members in a clearance relationship allowing orbiting motion of said one of the first and second rotary members about the central axis of the shaft, wherein the combination of the circular holes and the circular cylindrical posts provides a coupling that transmits rotating motion of said one of the first and second rotary members created by the orbiting motion thereof to the power output member;
- and
- (g) a plurality of circular cylindrical posts disposed on a circle concentric to the central axis of the shaft and rigidly affixed to a holder member supported by the frame and respectively engaging the plurality of circular holes included in the other of the first and second rotary members in a clearance relationship allowing orbiting motion of said the other of the first and second rotary member about the central axis of the shaft, wherein the combination of the circular holes and the circular cylindrical posts provides a coupling that disallows rotating motion of said the other of the first and second rotary member relative to said holder member;