Fluid supply system using one fluid medium to move a second fluid medium

摘要

A fluid supply system includes a pump body having a main bore connectible through inlet check valves to draw secondary fluid from a first fluid reservoir and through outlet check valves to supply it to a secondary fluid function upon reciprocation of a free piston in the main bore. The free piston includes a pair of coaxial driving pistons on either side which extend into main passages which are alternately connected to a pressurized primary fluid source to cause reciprocation of the free piston. A first spool valve which responds to the completion of a free piston stroke activates a second spool valve which changes the primary fluid source connections to the driving pistons.