Abstract: The pump has a drive shaft which is supported in a support housing by at least an upper bearing and a lower bearing. One end of the drive shaft is connected to a rotor disposed in a rotor chamber which borders the lower bearing and from which at least one lifting duct runs parallel to the support housing in the direction of the drive unit and an outlet for the pumped fluid. The free cross section of the support housing above the lower bearing is extended by at least one clearance gap which projects into the lifting duct and which is blocked off against the flow of liquid in the lifting duct.