F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
F04B7/00—Piston machines or pumps characterised by having positively-driven valving
F04B7/0003—Piston machines or pumps characterised by having positively-driven valving the distribution member forming both the inlet and discharge distributor for one single pumping chamber
F04B7/0011—Piston machines or pumps characterised by having positively-driven valving the distribution member forming both the inlet and discharge distributor for one single pumping chamber and having an oscillating movement