Rotary radial piston machine

Claim 1

A ROTARY FLUID MACHINE COMPRISING, IN COMBINATION, A CASING; AT LEAST ONE ROTOR ROTATABLY MOUNTED IN SAID CASING AND FORMED WITH ANGULARLY SPACED RADIAL BORES CONSTITUTING CYLINDERS; PISTONS RECIPROCABLE IN EACH OF SAID CYLINDERS TO VARY THE EFFECTIVE VOLUMES OF THE CYLINDERS TO DISPLACE FLUID RELATIVE TO SAID CYLINDERS; GUIDE MEANS SURROUNDING SAID ROTOR AND RECIPROCATING SAID PISTONS UPON ROTATION OF SAID ROTOR; SAID GUIDE MEANS HAVING AN ECCENTRICITY RELATIVE TO THE ROTOR AXIS TO DEFINE THE PISTON STROKES; SAID CYLINDERS BEING ARRANGED IN AT LEAST TWO GROUPS WITH THE CYLINDERS OF EACH GROUP HAVING THEIR AXIS IN A RESPECTIVE COMMON DIAMETRIC PLANE THROUGH SAID ROTOR, SAID PLANES BEING SPACED AXIALLY OF SAID ROTOR; SAID ROTOR HAVING AT LEAST TWO EXTERNAL ANNULAR RADIAL RIBS EACH CENTERED AXIALLY ON A RESPECTIVE ONE OF SAID DIAMETRIC PLANES, THE AXIAL WIDTHS OF SAID RIBS BEING LESS THAN THE DIAMETER OF THE ASSOCIATED BORES; SAID GUIDE MEANS BEING FORMED TO PROVIDE RADIALLY INWARDLY OPENING ANNULAR GROOVES ARRANGED TO HAVE SAID RIBS EXTEND AT LEAST PARTIALLY THEREINTO; SAID BORES BEING FORMED THROUGH SAID RIBS TO PROVIDE EXTENDED GUIDE SURFACES FOR SAID PISTONS, WITH RESULTANT AXIAL SLOTTING OF SAID RIBS AT ANGULARLY SPACED LOCATIONS EACH CENTERED ON A RESPECTIVE CYLINDER AXIS; THE CYLINDRICAL SURFACE OF SAID ROTOR