Abstract: The present invention relates to a reciprocating engine which has an improved reciprocating double ended piston which substantially reduces the size and weight of piston components. The double ended piston comprises a center portion between the two end portions. The center portion having at least one pair of racks located along the longitudinal axis either on the outside surface of a pair of flat surfaces or on opposed inside surfaces along a slot cut into the center portion. At least one crankless drive shaft having a gear or pair of gears mateable with the racks so that the crankless drive shaft (s) are continuously rotated.