ATOS VANE is cohering tightly to cam ring inner wall when the rotor is work, due to the action of centrifugal force and oil pressure inside the cartridge. In this way, When ATOS vane pump rotor rotates, blade under the action of centrifugal force and oil pressure, the tip close to the inner surface of the stator. So that the two blades of the rotor and the stator working volume surface constituted with the first small to large suction drain and then descending, the blades rotate a week, complete with two suction drain. It has high pressure rated, compact structure, low noise, high efficiency, long service life and convenient flow control.