Patent ID: 8206259

Claim:
A rotary actuator comprising: a rotatable output ring with a generally denticulate inner surface region and an output ring axis of rotation; a pair of stationary rings, each with a generally denticulate inner surface region and a stationary ring axis, each located on a different end of the output ring with the stationary ring axes in general alignment with the output ring axis; a generally cylindrical planet comprising distal outer regions that each have outer surfaces for supporting the planet, a generally denticulate central outer surface region that engages the denticulate inner surface region of the output ring, and generally denticulate intermediate outer surface regions that each engage the denticulate inner surface region of a respective one of the stationary rings, and a planet axis of rotation that is generally parallel to the output ring axis; and a pair of generally cylindrical planet carriers, each having a carrier axis of rotation in general alignment with the output ring axis, each carrier supporting the outer surface of a respective one of the distal outer regions of the planet to allow rotation of the planet about the planet axis and movement of the planet axis about the output ring axis in a generally circular path as the planet carriers rotate about their carrier axes of rotation; wherein rotation of the planet carriers about their carrier axes cause the cylindrical planet to rotate about its planet axis as it moves through its circular path about the output ring axis, thereby causing the output ring to rotate.