Abstract: A fluid rotary machine (10) includes an inner housing (12) provided with a manifold (68) for directing working fluid through the machine (10) and an outer housing (14) coupled to the inner housing (12) so that the outer housing (14) can rotate relative to the inner housing (12). A plurality of swinging gates (16) are supported along one longitudinal edge in corresponding sockets (38) formed along the inner circumferential surface (32) of outer housing (14). A plurality of elongated lobes (30) are supported on and evenly spaced about the inner housing (12). There is one intake port (24) and one exhaust port (26) between adjacent lobes (30). The gates (16) are biased so as to ordinarily seal against the inner housing (12). High pressure fluid enters through the inlet port (24) to a region between a lobe (30) and gate (16) causing the outer housing (14) to rotate. Eventually the gate (16) wipes across an exhaust port (26) venting the high pressure fluid through the exhaust port.