A rotary pump device includes a stator chamber with a cylindrical inner wall having intake and exhaust ports and a swinging abutment mounted therein, and a rotor eccentrically mounted on an axial drive shaft for rotation within the chamber. The rotor keeps continuous wiping contact with the chamber wall while the swinging abutment maintains contact with the rotor to partition the intake and outlet ports. In a single abutment configuration, a full intake/exhaust cycle occurs every 360° of rotor travel.