Opposed-piston Engine - Free-piston Engine

Free-piston Engine

An interesting variation on the opposed-piston engine is the free-piston engine, which was patented in 1934 by Raúl Pateras de Pescara. It has no crankshaft, and the pistons are returned after each firing stroke by compression and expansion of air in a separate cylinder. Early applications were for use as an air compressor or as a gas generator for a gas turbine, such as the Pratt & Whitney PT1 design. There is now renewed interest in it for powering vehicles by using it to drive a linear alternator.