The pump consists of a rotor 1, a stator 2, a blade 3, an oil plate and an end cap. The inner surface of the stator is a cylindrical hole. There is an eccentric between the rotor and the stator. Blade in the groove of the rotor can be flexible sliding, in the rotor rotation of the centrifugal force and through the blade root pressure oil, the top of the blade is snapped to the inner surface of the stator, so that the two adjacent blades, oil plate, stator and rotor formed a sealed work cavity. When the rotor is rotated counterclockwise, the blade on the right side of the figure extends outward, the volume of the sealing chamber increases gradually, resulting in a vacuum, which is sucked through the suction port 6 and the oil Tray 5 on the window. And on the left side of the graph. The blade is indented, the volume of the sealing chamber is gradually reduced, and the oil in the sealing chamber is pressed out through the other window of the oil tray and the pressure Port 1 and output to the system. This pump in the rotor to a turn process, suction oil every time, it is called single-action pump. The rotor is subjected to radial hydraulic imbalance force, so it is also called unbalanced pump, its bearing load is larger. Change the eccentricity between the stator and the rotor, it can change the displacement of the pump, so this pump is a variable pump.