Pressure loaded gear pump

Claim 1

IN A PRESSURE GENERATING PUMP OF THE TYPE INCLUDING A HOUSING CONTAINING INTERMESHING GEARS AND HAVING AN INLET LEADING TO AND AN OUTLET LEADING FROM SAID HOUSING, AN AXIALLY MOVABLE THRUST PLATE HAVING A SEALING SURFACE IN SEALING RELATIONSHIP WITH THE SIDE FACE OF ONE OF SAID GEARS, THE SIDE OF SAID THRUST PLATE OPPOSITE FROM SAID SEALING SURFACE COMPRISING A MOTIVE SURFACE ADAPTED TO BE SUBJECTED TO PUMP GENERATED PRESSURE FLUID, A PUMP HOUSING MEMBER FORMING WITH SAID MOTIVE SURFACE A PRESSURE CHAMBER, MEANS FOR SUPPLYING SAID PRESSURE CHAMBER WITH PUMP GENERATED PRESSURE FLUID, AN OPENING EXTENDING THROUGH SAID THRUST PLATE FROM SAID MOTIVE SURFACE SIDE TO SAID SEALING SURFACE SIDE, PISTON MEANS MOUNTED IN SAID OPENING, SAID PISTON MEANS EXTENDING INTO SAID PRESSURE CHAMBER AND INTO SEALING ABUTMENT WITH SAID HOUSING MEMBER, AND FLUID PASSAGE MEANS IN SAID PISTON MEANS FOR VENTING THE END OF SAID PISTON MEANS IN ABUTMENT WITH SAID HOUSING MEMBER TO THE INLET WHEREBY THE AREA OF SAID PISTON IS SUBTRACTED FROM THE AREA OF SAID MOTIVE SURFACE SUBJECT TO PUMP GENERATED PRESSURE FLUID TO COUNTERACT TWISTING OF SAID THRUST PLATE.