Abstract: The invention relates to a gas friction vacuum pump having at least two differently configured pump stages each having a rotor section and a housing section. In order to adapt the pump to different applications, the pump stages are detachably connected with each other so that different inlet stages can be mounted on the high-vacuum side.

Abstract: A friction pump includes a generally cylindrical first housing part, a generally cylindrical second housing part projecting axially into the inner space of the first housing part; a bearing mounted in the second housing part coaxially therewith; and a pump rotor supported for rotation in the bearing. The pump rotor has a cylindrical shell surrounding the second housing part. The pump further has a drive motor mounted in the second housing part for driving the pump rotor; and a helical channel defined between the inner face of the first housing part and the outer face of the pump rotor for pumping gases upon rotation of the pump rotor. The second housing part, the bearing, the pump rotor and the drive motor form a single structural unit that can be axially removed from the first housing part after releasing a coupler between the two housing parts.

Abstract: A housing 3 disposed below the rotor accommodates a driving motor 13, shaft bearings 14, 15 and an oil sump 21. An evacuating line 31 which traverses the wall the housing 3 connects a vacuum pump to the interior 18 of the housing. In order to avoid the loss of oil in the housing or the bearings, the evacuating line 31 and the oil sump 21 are directly connected.

Abstract: A gas friction pump has an inlet arranged to be coupled to a vessel to be evacuated; an outlet and an outlet-side pumping stage formed of a helical gas pumping channel. The pump further has a scavenging gas inlet circumferentially surrounding the helical gas pumping channel for exposing the channel to a scavenging gas.