Abstract: The invention provides a two-rotors screw compressor having active cooling means on the pressure side of the motive rotor.

Abstract: A vacuum pump contains two rotary displacement rotor (8) that engage each other, in particular in a convoluted manner, inside in expansion chamber through which flows a stream in the axial direction. The rotors are mounted in cantilever at the delivery side and are linked each to a driving motor (35, 36). Each rotor (8) forms together with its shaft (20), a stationary bearing body (7) and a bearing (21, 22) delimited by the shaft (20) and the bearing body (7) a module that may be removed as a single unit from the housing (3). The rotor (35) of the driving motor is preferably also part of said module.

Abstract: Fluid-flow machine having shaft (1) which is mounted in an axially fixed fashion, and a balancing piston (6) firmly arranged thereon. In order to reduce the leakage flow, the balancing piston (6) is partially replaced by a porting ring (12) which forms with the balancing piston a choke gap (11), through which radial flow occurs, and a cylindrical upstream throttle (13) through which axial flow occurs.