Hydraulic pump

Claim 1

IN AN INTERNAL-GEAR PUMP, MESHING OUTER AND INNER PUMP ELEMENTS OF WHICH THE INNER PUMP ELEMENT HAS ONE LESS TOOTH THAN THE OUTER ELEMENT AND THE OUTER ELEMENT IS STATIONARY, A HOUSING TO WHICH SAID OUTER ELEMENT IS SECURED, SAID HOUSING HAVING A BORE COAXIAL WITH THE OUTER ELEMENT, A VALVE SLEEVE ROTATABLY SUPPORTED IN SAID BORE IN AXIALLY SPACED RELATION TO SAID ELEMENTS, SAID HOUSING HAVING A CIRCUMFERENTIAL SERIES OF PORTS OPENING INTO SAID BORE WITHIN THE AXIAL LIMITS OF SAID VALVE SLEEVE AND COMMUNICATING RESPECTIVELY WITH THE SPACES BETWEEN THE TEETH OF SAID OUTER ELEMENT, SAID HOUSING ALSO HAVING INLET AND OUTLET PASSAGES, MEANS FOR COMMUTATIVELY CONNECTING ONE OF SAID PASSAGES TO SAID PORTS, SAID MEANS COMPRISING A CIRCUMFERENTIAL SERIES OF AXIALLY EXTENDING GROOVES FORMED IN THE OUTER SURFACE OF SAID VALVE SLEEVE, SAID GROOVES OVERLAPPING SAID PORTS AXIALLY AND CORRESPONDING IN NUMBER TO THE TEETH OF SAID INNER ELEMENT, THE SECOND OF SAID PASSAGES BEING IN OPEN COMMUNICATION WITH THE INTERIOR OF SAID SLEEVE AND SAID SLEEVE BEING PROVIDED IN THE PLANE OF SAID PORTS WITH A CIRCUMFERENTIAL SERIES OF RADIAL PASSAGES CORRESPONDING IN NUMBER TO THE TEETH OF SAID INNER ELEMENT FOR PROVIDING COMMUTATIVE CONNECTION BETWEEN THE INTERIOR OF THE VALVE SLEEVE AND SAID PORTS, A DRIVE SHAFT ROTATABLY MOUNTED IN SAID HOUSING COAXIALLY WITH THE VALVE SLEEVE AND ON THE OPPOSITE AXIAL SIDE THEREOF FROM SAID INNER AND OUTER ELEMENTS, MEANS OPERATIVELY INTERCONNECTING SAID DRIVE SHAFT AND VALVE SLEEVE FOR JOINT ROTATION, AND MEANS FOR TRANSMITTING DRIVE FROM SAID DRIVE SHAFT TO THE INNER PUMP ELEMENT TO CAUSE IT TO ROTATE ON ITS AXIS AT THE SAME RATE AS THE DRIVE SHAFT, SAID LAST NAMED MEANS COMPRISING A SECOND SHAFT EXTENDING GENERALLY AXIALLY THROUGH SAID VALVE SLEEVE AND HAVING ITS ENDS DRIVINGLY CONNECTED RESPECTIVELY TO SAID DRIVE SHAFT AND INNER ELEMENT.