Piston pump improvement

Claim 1

A PISTON PUMP COMPRISING: A MEMBER HAVING A PLURALITY OF ANNULARLY ARRNGED PISTON CYLINDER, A PLURALITY OF PISTON MOUNTED IN EACH OF SAID PISTON CYLINDERS, EACH OF SAID PISTON HAVING A CYLINDRICAL PORTION EXTENDING SLIDABLY WITHIN SAID PISTON CYLINDERS AND A GENERALLY SPHERICAL END EXTENDING EXTERNALLY OF SAID CYLINDERS, A TILTABLE WOBBLE PLATE MEMBER, A PLURALITY OF STEEL SHOE MEMBERS ONE FOR EACH OF SAID PISTONS HAVING A BEARING SURFACE IN SLIDABLE CONTACT WITH SAID WOBBLE PLATE AND A SOCKET END FITTED OVER SAID SPHERICAL END OF SAID PISTONS, SAID SHOES EACH HAVING AN AXIALLY CENTERED RECESS EXTENDING INWARDLY FROM SAID BEARING SURFACE, EACH OF SAID PLURALITY OF PISTONS HAVING A FIRST AXIAL FLUID PASSAGE, EACH OF SAID SHOES HAVING A SECOND FLUID PASSAGE FLUIDLY CONNECTING SAID RECESS AND SAID FIRST FLUID PASSAGE TO TRANSMIT FLUID FROM SAID PISTON CYLINDERS TO SAID RECESS, EACH OF SAID SHOES HAVING AN INNER CIRCULAR AND OUTER CIRCULAR PROJECTION OF DENSE METAL ON SAID BEARING SURFACE FORMED ADJACENT SAID AXIALLY-CENTERED RECESS AND OUTER RADIAL EDGE OF SAID SHOES RESPECTIVELY TO FORM AN ANNULAR RECESS THEREBETWEEN; AN ANNULAR RING OF RELATIVELY POROUS BEARING METAL DISPOSED IN SAID ANNULAR RECESS HAVING AN UPPER SURFACE FLUSH WITH SAID INNER AND OUTER CIRCULAR PROJECTIONS TO PROVIDE A SMOOTH BEARING SURFACE.