The rotor rotates eccentrically within a cylindrical body. The rotor has grooves into which the vanes are free to slide. During operation centrifugal force pushes the vanes out into contact with the body. This creates closed spaces between the blades that gradually increase the volume by bringing in air from the container to be emptied and expelling it through the exhaust. If used as a compressor, the air drawn in from the environment is conveyed to the exhaust to be used. Oil lubricated versions allow deeper levels of vacuum to be achieved.