Low-pressure pump

A rotary piston pump for gaseous media, comprising:

• an axially and radially supported power part, embodied as a spherical segment of a spur tooth;
• a blocking part of a same radial sealing diameter, also embodied as a spherical segment of a spur tooth and driven by the power part;
• work chambers between the power part and the blocking part, the power part and blocking part are guided radially sealingly in a pump housing;
• the pump, formed of the power part and blocking part, is present in double fashion in each case, which double fashion pumps are driven in common, and the work chambers thereof can be made to communicate with one another,
• wherein doubly present power parts are disposed coaxially on a drive side, the first power part is driven by a drive mechanism disposed on the drive side, likewise coaxially, in a housing, and the second power part is rotated in rotationally locked fashion by the first power part,
• wherein between the power parts, an elastic element urging the power parts toward the blocking parts is disposed, and
• wherein a helical spring, disposed coaxially with the power parts, serves as the elastic element.