Abstract: A gas-actuated reciprocal drive apparatus has a double-acting piston in a pneumatic cylinder having a chamber at each end. Gas from an area of higher pressure in a compressed gas system flows into a first chamber, while the second chamber is in fluid communication with an area of lower pressure in the gas system. The piston moves toward the second chamber, purging gas therein back to the lower-pressure area in the gas system, without any venting to the atmosphere. A four-way gas valve reverses the piston motion after each stroke, by reversing the chambers' gas connections.

Abstract: A pressurized working environment for a pneumatic device which permits emission-free utilization of the potential mechanical energy of pressure differentials within compressed gas systems is disclosed. The pneumatic device is contained within a pressure vessel and the pneumatic device exhaust is in fluid communication with the interior of the pressure vessel. In use, the interior of the pressure vessel is in fluid communication with an area of lower pressure in the compressed gas system and the pneumatic device intake is in fluid communication with an area of higher pressure in the compressed gas system. In use, the gas from the area of higher pressure drives the pneumatic device and is then exhausted to the area of lower pressure.