Abstract: A displacement machine for compressible media has at least two shafts with rotors which are designed as helical profile bodies. During rotation, the profiles intermesh like gears and run free of contact relative to one another. The lead of the helical profile bodies decreases from the inlet end to the outlet end and have a double-start design, with the leads at the inlet end and outlet end of the helical profile bodies being constant, and the intermediate lead decreasing continuously from the larger lead at the inlet end to the smaller lead at the outlet end.

Abstract: Side-channel centrifugal pump in sectional construction, the stage packs of which comprise a suction connector (6), a pressure connector (7), a vane (10) and a casing shell element (8, 9). In order to reduce the structural complexity, the suction and pressure connectors (6, 7) are formed as sheet-metal parts and are disposed in an annular casing shell element (8, 9). The centering of the suction and pressure connectors (6, 7) is expediently effected from the shaft.