Hydraulic pumps

Claim 1

A FLUID COMPRISING A STATOR CASING STRUCTURE, A ROTATABLE SHAFT EXTENDING THROUGH AND SUPPORTED BY SAID STATOR CASING, A ROTOR SECURED ON SAID SHAFT, SAID STATOR CASING HAVING A CHAMBER PROVIDED WITH AN ECCENTRIC CAM SURFACE, SAID ROTOR HAVING PUMPING CHAMBERS AND PUMPING INSTUMENTATLITIES SLIDABLY CONTACTING SAID CAM SURFACE AND OPERABLE ON ROTOR ROTATION TO PUMP FLUID INTO AND OUT OF SAID PUMPING CHAMBERS, SAID ROTOR AND SAID CASING HAVING SLIDABLEY CONTACTING COMPLEMENTARY FACES DISPOSED IN A PLANE NORMAL TO THE SHAFT AXIS, INLET AND EXHAUST PASSAGES IN SAID STATOR HAVING INTAKE AND EXHAUST PASSAGES COMMUNICATING WITH THE PUMPING CHAMBER AND OPENING TO SAID FACES IN TIMED ALTERNATE REGISTRATION WITH THE STATOR CASING INTAKE AND EXHAUST PASSGE OPENINGS, SAID CASING HAVING ANA END CAP ENCLOSING THE END OF SAID SHAFT DISPOSED ON THE SIDE OF THE ROTOR OPPOSITE TO SAID FACES, SAID END CAP HAVING A RECESS WITH ITS WALLS AXIALLY AND RADIALLY SPACED FROM THE END OF SAID SHAFT AND A PORT COMMUNICATION WITH THE EXHAUST PASSATE OF SAID STATOR CASING WHEREBY TO ADMIT FLUID PRESSURE TO THE END OF SAID SHAFT TO PROVIDE SEALING CONTACT FORCES ON SAID CONTACTING FACES, SPRING MEANS COMPRESSED BETWEEN THE END OF THE SHAFT AND SAID CAP TO PROVIDE PRESSURE URGING SAID FACES INTO SEALING CONTACT WHEN FLUID PRESSURE IS LOWER AT SLOW PUMP SPEEDS, AND A SEPARATE LEAKAGE SEALING ELEMENT IN SAID CAP RECESS CIRCUMFERENTIALLY ENCLOSING AND CONTACTING THE END OF SAID SHAFT AND CONTACTING THE ADJACENT AREA OF SAID CASING THROUGH WHICH SAID SHAFT END EXTENDS, SAID SEALING ELEMENT EXPOSED TO FLUID PRESSURE TO BE URGED RADIALLY INWARDLY ON SAID SHAFT END AND AXIALLY AGAINST SAID CASING ADJACENT AREA, AND SECOND SPRING MEANS COMPRESSED BETWEEN SAID CAP AND SAID SEALING ELEMENT TO PROVIDE PRESSURE URGING SAID ELEMENT AND CASING ADJACENT AREA INTO SEALING CONTACT WHEN SAID FLUID PRESSURE IS LOWER AT SLOW PUMP SPEEDS.