Slipper sealing means for a dual acting pump

Claim 1

A PUMP COMPRISING A CASING HAVING A CYLINDRICAL BORE WALL FORMING A PUMPING CHAMBER, A ROTOR ROTATABLE ON AN OFFSET AXIS IN SAID PUMPING CHAMBER, MEANS FORMING A PERIPHERAL AXIALLY EXTENDING RECESS IN SAID ROTOR HAVING GENERALLY PARALLEL SIDE WALLS AND A BOTTOM WALL, A SLIPPER IN SAID RECESS HAVING A RADIAL OUTER SEALING SURFACE CURVED TO ENGAGE THE ADJOINING BORE WALL WITH SURFACE CONTACT AND INCLUDING FIRST AND SECOND SIDE WALLS DISPOSED ADJACENT SAID SIDE WALLS OF SAID RECESSES, SAID FIRST AND SECOND SIDE WALLS BEING SHAPED TO PERMIT SAID SLIPPER TO ROCK AND TO MOVE INWARDLY AND OUTWARDLY OF SAID RECESS IN FOLLOWING SAID BORE WALL, SAID FIRST SIDE WALL OF SAID SLIPPER ENGAGING THE ADJOINING SIDE WALL OF SAID RECESS, MEANS FORMING A SEALING PIN INTERPOSED BETWEEN SAID SECOND SIDE WALL OF SAID SLIPPER AND THE OTHER SIDE WALL OF SAID RECESS, AND RADIALLY OUTER AND INNER PORTING MEANS IN SAID CASING RESPECTIVELY COMMUNICATING WITH SAID PUMPING CHAMBER RADIALLY OUTWARDLY OF SAID SEALING PIN TO FORM A FIRST PUMPING CIRCUIT AND WITH SAID RECESS RADIALLY INWARDLY OF SAID SEALING PIN TO FORM A SECOND PUMPING CIRCUIT, A SEALING PIN RECESS IN ONE OF SAID SIDE WALLS RECEIVING SAID SEALING PIN AND HAVING MEANS OF A FORM AND INWARD EXTENT SUCH THAT THE PIN WILL MOVE INWARDLY AWAY FROM AN ADJOINING SIDE WALL OUT OF SEALING CONTACT TO RELIEVE EXCESSIVE PRESSURES IN THE FIRST PUMPING CIRCUIT AND WILL MOVE OUTWARDLY AGAINST THE ADJOINING WALLS IN SEALING CONTACT IN RESPONSE TO CENTRIFUGAL FORCE TO RETAIN PRESSURE IN THE SECOND PUMPING CIRCUIT.