A multicylinder internal combustion engine includes a plurality of reciprocating pistons each having a piston rod connected to a ball cage arrangement for converting reciprocating motion of the piston rod into rotation of a shaft coaxial with the piston rod. A one way clutch connects the coaxial shaft with an output to drive the output in one direction. A parallelogram linkage connects the piston assemblies together causing them to move in concert through the cycles of the engine.