A rotary vane vacuum pump 
is an oil-sealed rotary displacement pump. The pumping system consists of a casing (1), an eccentrically set up rotor (2), vanes that move radially under spring pressure (3) and the inlet and outlet (4). … The Rotor moves with the aid of a motor mounted on it.
Uses. Vane pumps are commonly used as high-pressure hydraulic pumps and in automobiles, including supercharging, power-steering, air-con and automatic-transmitting pumps. Pumps for mid-range pressures consist of applications such as carbonators for fountain soft-drink dispensers and espresso coffee machines.
The easiest vane pump has a circular rotor rotating inside a larger circular cavity. The centers of the two circles are offset, leading to eccentricity. … The actions of the vane drives out the same level of liquid with each rotation. Multistage rotary-vane vacuum pumps can attain pressures only 10 mbar (0.0001 Pa).