Abstract: A motion change transmission includes a rotor rotationally supported by and/or within a framing assemblage or housing. The face of the rotor is provided with alternating, axially and circumferentially extending hills and valleys. At least one rod is disposed transversely relative to the rotor and is pivotal in a given plane relative to the assemblage or housing and is operatively engageable with the face of the rotor such that when one end of the rod traverses a rotor hill, the other end of the rod simultaneously traverses a rotor valley. Either or both ends of the rod are connected to reciprocating members. When means are provided for driving the reciprocating members, the transmission provides for the conversion of reciprocating motion to rotary motion. And when means are provided for driving the rotor, the transmission provides for the conversion of rotary motion to reciprocating motion.