A two-stage hydraulic pump includes a rotor, a ring, and a plurality of rollers disposed in slots formed on the rotor. The pump has two inlet ports and two outlet ports, which are disposed inwardly and outwardly, respectively, of the rollers. A valve mechanism is incorporated which provides for flow directional control of the output flow of the pump between one portion of the discharge ports and a portion of the inlet ports when a low output flow is desired and blocking that interconnection while connecting the inner portion of the suction inlet side with a reservoir.