Abstract: A reciprocating opposed piston mechanism having at least one cylinder assembly mounted to oscillate in rotary relation to a block about a central axis, two opposing pistons reciprocally mounted within the cylinder, each of the pistons having an eccentric bearing mounted in its rear portion with an eccentric rotatably mounted in each eccentric bearing, each eccentric fixedly mounted to an eccentric shaft. Each eccentric shaft is mounted to the engine block and rotatable about an eccentric shaft axis equally spaced in opposite directions from the central cylinder oscillation axis. Timing mechanisms in force transmission relation to each of the eccentric shafts is provided to maintain the eccentrics in each cylinder assembly 180.degree. out of rotary phase. An even number of such cylinder assemblies, adjacently 180.degree. out of phase, may be assembled to form the mechanism of this invention. The mechanism is useful as an internal or external combustion engine, compressor or prime mover.

Abstract: A motion conversion device for converting between the reciprocating motion of the pistons in a Stirling engine and the rotating motion of its output shaft, and for changing the stroke and phase of the pistons, includes a lever pivoted at one end and having a cam follower at the other end. The piston rod engages the lever intermediate its ends and the cam follower engages a cam keyed to the output shaft. The lever pivot can be moved to change the length of the moment arm defined between the cam follower and the piston rod the change the piston stroke and force exerted on the cam, and the levers can be moved in opposite directions to change the phase between pistons.