Sarich orbital engine

The Sarich orbital engine is a type of internal combustion engine, invented in 1972 by Ralph Sarich, an engineer from Perth, Australia, which features orbital rather than reciprocating motion of its central piston. It differs from the conceptually similar Wankel engine by using a generally prismatic shaped piston that orbits the axis of the engine, without rotation, rather than the rotating trilobular rotor of the Wankel.