A rotary vacuum pump is proposed, having a rotor with vanes which rotates eccentrically within a housing bore. Each vane is coupled with a body which is ineffective at relatively low pump rpm; however, at higher rpm, the body engages the vane in such a manner that it removes the vane from its track within the housing bore.In this manner, an rpm-dependent shutoff device is created for the pump. In cooperation with the furnishing of underpressure as an auxiliary pressure in motor vehicles, the pump is used to supplement the underpressure which prevails when the internal combustion engine is at low, idling rpm; this prevailing underpressure is at a very low pressure level, and so when it is thus supplemented there is sufficient auxiliary vacuum force available over the entire rpm range.