Variable-volume fluid motor

Claim 1

IN COMBINATION, A HOUSING, A ROTOR JOURNAL-MOUNTED IN SAID HOUSING AND HAVING A PLURALITY OF OUTWARDLY PROJECTING AND CIRCUMFERENTIALLY SPACED VANES WHICH ARE MOVABLE INWARDLY AND OUTWARDLY RELATIVE TO THE ROTOR AND ARE YIELDINGLY URGED OUTWARDLY, FLEXIBLE RING MEANS CIRCUMSCRIBING SAID ROTOR IN RADIALLY SPACED RELATION THERETO AND ENGAGED BY SAID VANES, TWO PAIRS OF DIAGONALLY OPPOSITE FULCRUM MEANS IN SAID HOUSING ENGAGED BY SAID RING MEANS FOR RESTRAINING EXPANSION OF THE RING MEANS THEREAT, TWO PAIRS OF DIAGONALLY OPPOSITE CHAMBERS IN SAID HOUSING BETWEEN SAID FULCRUM MEANS EXPOSED TO THE OUTER SURFACE OF SAID SPRING MEANS, TWO PAIRS OF DIAGONALLY OPPOSITE PORTS IN SAID HOUSING LOCATED ENDWISE OF SAID RING MEANS AND EXPOSED TO THE SPACE BETWEEN SAID ROTOR AND RING MEANS, EACH SAID PAIR OF PORTS BEING GENERALLY CENTERED CIRCUMFERENTIALLY OF THE ROTOR RELATIVE TO A RESPECTIVE PAIR OF SAID FULCRUM MEANS AND SAID PORTS BEING SPACED APART SUFFICIENTLY TO BE ISOLATED FROM ONE ANOTHER BY SAID VANES, MEANS FOR SUPPLYING FLUID TO ONE OF SAID PAIRS OF PORTS AND FOR DISCHARGING SAID FLUID FROM THE OTHER PAIR OF PORTS, AND CONTROL FLUID MEANS IN SAID CHAMBERS FOR EXERTING A PRESSURE DIFFERENTIAL AS BETWEEN SAID PAIRS OF CHAMBERS FOR DEFORMING SAID RING MEANS BETWEEN SAID FULCRUM MEANS TO A GENERALLY ELLIPTICAL SHAPE, THEREBY DETERMINING THE FLUID FLOW PER REVOLUTION OF THE ROTOR.