Vane-type rotary pumps

Claim 1

IN A PUMP OF THE KIND DESCRIBED, A HOUSING HAVING AN INLET AND AN OUTLET, A STATOR RING IN SAID HOUSING AND HAVING A ROTOR THEREIN AND SAID ROTOR AND STATOR RING HAVING AXIAL FREEDOM, SAID STATOR RING HAVING WALLS SURROUNDING SAID ROTOR AND EFFECTING PUMP CHAMBER MEANS THEREFOR, AND MEANS ROTATIVELY MOUNTING SAID ROTOR, A SEALING PLATE ON EACH SIDE OF SAID ROTOR AND STATOR RING WITHIN SAID HOUSING, SAID PLATES BEING INDEPENDENTLY AXIALLY MOVABLE RELATIVE TO SAID ROTOR AND STATOR AND EACH PLATE HAVING A SIDE CONTIGUOUS WITH SAID ROTOR AND SAID STATOR RING, A PRESSURE CHAMBER MEANS ON EACH OF THE OTHER SIDES OF SAID PLATES AND SAID PRESSURE CHAMBER MEANS BEING CONNECTED TO SAID HOUSING OUTLET PASSAGES CONNECTING THE PUMP CHAMBER MEANS WITH SAID PRESSURE CHAMBER MEANS WHEREBY FLUID PRESSURE IS EXERTED ON SAID PLATES TO PRESS SAID PLATES AGAINST SAID ROTOR AND STATOR RING FOR SEALING OF SAID PUMP CHAMBER MEANS IN SAID STATOR RING, AND SHOULDER MEANS IN SAID HOUSING AGAINST WHICH ONE OF SAID PLATES ABUTS, AND MEANS FOR PROVIDING A DIFFERENTIAL BIAS ON SAID PLATES TO EFFECT A FORCE AGAINST SAID ROTOR AND STATOR RING TO SAID ONE PLATE TO EFFECT ABUTMENT THEREOF AGAINST SAID SHOULDER MEANS.