Fluid driven pump with one-way valve in fluid inlet

A fluid driven pump comprising a pump housing defining a recess including therein a moveable wall which divides said recess into a variable volume driving chamber and a variable volume pumping chamber, a pressure inlet communicable with said driving chamber and adapted to communicate with a source of pressure which oscillates between an operating pressure and a pressure different from the operating pressure, said pressure inlet including one-way valve means for permitting fluid under the operating pressure to communicate with said driving chamber and thereby to move said moveable wall in one direction when said driving chamber is in communication with said pressure inlet, a vent communicable with said driving chamber and adapted to be in communication with a source of pressure different from said operating pressure, means for moving said moveable wall in the opposite direction when said driving chamber is in communication with said vent, and means for selectively controlling communication of said driving chamber with said pressure inlet and said vent, said selective controlling means comprising a valve housing defining a valve chamber including a first end and a second end, a first pressure passageway extending between said pressure inlet and said valve chamber, a second pressure passageway extending from said valve chamber to said driving chamber, one of said pressure passageways communicating with said first end of said valve chamber, a first vent passageway extending from said valve chamber to said vent, a second vent passageway extending from said driving chamber to said valve chamber, one of said vent passageways communicating with said second end of said valve chamber, a shuttle valve in said valve chamber and moveable between a first position adjacent said first end wherein said first pressure passageway is in communication with said second pressure passageway and said first vent passageway is not in communication with said second vent passageway, and a second position adjacent said second end wherein said first vent passageway is in communication with said second vent passageway and said first pressure passageway is not in communication with said second pressure passageway, and means connecting said shuttle valve to said moveable wall and providing for lost motion between said shuttle valve and said moveable wall.