free piston engine is an integrated combination of an internal combustion
engine and a hydraulic pump. The core of this engine is a combustion piston
directly coupled to a hydraulic plunger. The piston is not connected to
any mechanism but is free to move within the limitations of the cylinders.
In this way the energy of the combustion process is almost directly converted
into hydraulic energy. Compared to a conventional combination of a pump
and a combustion engine, the number of parts is reduced to approximately