The pump has a pump housing (10) comprising a rotor (30) rotated within a curved running surface. A locking element i.e. lever, is provided at the rotor and pivoted between two positions. Geometries of a drive shaft and the locking element are formed such that the rotor is displaced and rotated in one position of the locking element relative to the drive shaft, while the rotor is coupled with the drive shaft in another position of the locking element both in an axial direction and in a rotation direction by a form closure.
