Internal-combustion engines having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which the working piston rotates or oscillates upon its longitudinal axis and that of the working cylinder as it reciprocates therein and in so doing opens and closes in proper order the various ports necessary to supply combustible mixture to and to permit the exhaust of the burned gases from the engine, the periphery of the piston or an extension thereof forming a closure for the supply and exhaust ports when they are required to be closed.
