Hydraulic pumps

Claim 1

A FLUID PUMP COMPRISING A STATOR CASING STRUCTURE, A POWER SHAFT SUPPORTED BY SAID STATOR CASING STRUCTURE, A ROTOR SECURED ON SAID SHAFT, SAID STATOR CASING STRUCTURE PROVIDED WITH A CHAMBER HAVING AN ANNULAR PERIPHERAL CAM SURFACE ECCENTRIC TO THE SHAFT AXIS, SAID ROTOR HAVING A PLURALITY OF ANGULARLY SPACED RADIALLY EXTENDING FLUID PUMPING INSTRUMENTALITIES, EACH COMPRISING A PUMP CHAMBER AND A PUMP PLUNGER RECIPROCATINGLY SUPPORTED BY SAID ROTOR IN SAID PUMP CHAMBER, AND A SHOE MOVABLY CARRIED ON THE OUTER END OF THE PUMP PLUNGER AND CONSTRUCTED TO SLIDABLY CONTACT THE ECCENTRIC CAM SURFACE OF SAID STATOR CASING STRUCTURE, FLUID INTAKE AND EXHAUST MEANS FOR SAID PUMPING INSTRUMENTALITIES, AND A FREE FLOATING ANNULAR SHOE RETAINING RING ASSEMBLY DISPOSED CONCENTRIC WITH RESPECT TO THE ANNULAR PERIPHERAL CAM SURFACE OF THE STATOR CASING CHAMBER AND ENGAGED WITH SAID SHOES TO RETAIN SAME IN POSITION FOR OPERABLE CONTACT WITH SAID CAM SURFACE AND TO RESTRAIN SAID SHOES FROM ROTARY DISPLACEMENT ABOUT THE PUMP PLUNGER AXIS, SAID RING ASSEMBLY BEING ROTATABLE WITH RESPECT TO SAID ROTOR AND TO SAID STATOR CASING STRUCTURE, SAID FREE FLOATING ANNULAR SHOE RETAINING RING ASSEMBLY COMPRISING A PAIR OF AXIALLY SPACED ANNULAR RINGS ENGAGING THE RADIALLY INNER SIDES OF SAID SHOES, AND MEANS FIXING SAID RINGS IN SAID SPACED RELATION WITH RESPECT TO EACH OTHER, SAID MEANS FIXING SAID RINGS IN SPACED RELATION COMPRISING CROSS MEMBERS SECURED TO BOTH RINGS AND WHICH EXTEND INTERMEDIATE ADJACENT SHOES, ONE OR MORE OF SAID CROSS MEMBERS BEING ENGAGED BY A SHOE TO EFFECT ROTATION OF SAID RETAINING RING ASSEMBLY WITH SAID ROTOR.