[Image:Rotary vane pump.svg|thumb|300px|An eccentric rotary-vane pump. Note that modern pumps have an area contact between rotor and stator (and not a line contact).
1. pump housing
2. rotor
3. vanes
4. spring]] A rotary vane pump is a positive-displacement pump that consists of vanes mounted to a rotor that rotates inside of a cavity. In some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates. It was invented by Charles C. Barnes of Sackville, New Brunswick, who patented it on June 16, 1874.