Abstract: In a rotary screw machine, a shaft journal (7) of one of the rotors (6) is mounted in main thrust bearings (9, 10) and a balancing thrust bearing (11 ), the latter being located outermost on the shaft journal (7). The main thrust bearings (9, 10) are clamped towards the low pressure end of the machine. The balancing thrust bearing (11) is affected by a thrust balancing device for counter-acting the gas forces on the rotor (6), thereby reducing the force that has to be transferred by the main thrust bearing.

Abstract: The invention relates to a rotary screw compressor with liquid-injection means. The axes of the rotors (18, 20) are in a horizontal plane and the inlet channel (26) reaches the compressor from below. According to the invention there are provided means for preventing that liquid leaking out from the working space of the compressor through the inlet port (46) reaches the inlet channel (26). These means include partition walls (34, 36) mounted in an inlet chamber (28) connecting the inlet channel (26) to the inlet port (46).

Abstract: A screw rotor machine comprises a pair of intermeshing rotors (3) having helical lands and intervening grooves and a casing with a working space generally comprised of two intersecting bores, each enclosing one of the rotors (3). Each rotor (3) has a cylindrical projection (9) passing through a hole (8) in an end wall (5) at the high pressure end of the machine into a bearing chamber. To prevent gas leakage from the working space to the bearing chamber there is provided an annular element (15; 23) surrounding each rotor projection (9) and non-rotatably fixed to the casing. The annular element is provided with one axial (19; 24) and one radial (20; 21) sealing surface, one surface (19; 21) cooperating with the casing and the other surface (20; 24) cooperating with the rotor projection (9) by a slight or zero contact force. The annular element (15; 23) is movable almost without friction in the direction of the contact force.

Abstract: A rotary screw compressor with a lift valve comprising a valve member having two rigidly connected cylindrical sections of different diameter. The valve member is displaceably mounted in a valve housing extending through the high pressure end wall of the compressor. The valve housing sealingly surrounds each of the cylindrical sections. The section of the smaller diameter and the corresponding part of the valve housing face the working space of the machine. The lift valve is mounted such that the direction of motion of the valve member is inclined relative to the axial direction of the compressor.

Abstract: A housing (1) of a rotary machine comprises a low-pressure side (2) and a high-pressure side (3), working-fluid inlet and outlet channels, and at least one rotor (7), which when the machine is working is urged by a working fluid towards the low-pressure side (2). The rotor includes a thrust balancing arrangement (15, 16) for relieving the load on the thrust bearings (11) of the machine, through the medium of an auxiliary bearing (17) and in dependence on pressure fluid supplied to the thrust balancing arrangement, the pressure of which fluid is contingent on the operating conditions of the machine. A relatively large part of the axial load is taken-up by an auxiliary thrust bearing (17), which is readily replaceable. The auxiliary bearing (17) is mounted on an outermost part of the rotor journal shaft (18), on the high-pressure side (3) of the rotor, between a detachable locking device (27) for the auxiliary bearing (17) and the thrust balancing arrangement.

Abstract: A screw compressor having two rotors (2,3) rotatably journalled for mutual meshing engagement in a respective working chamber (4,5) of a compressor housing (1). For the purpose of regulating the pressure ratio and the capacity of the compressor, a composite slide assembly comprising two slides (17,18) is mounted for axial movement in a recess (6) in the housing (1), the composite slide having two flanks which form a continuous wall in the two working chambers (4,5). The two slides are individually movable and, for the purpose of improving the regulating function one of the slides (18) is provided with a flank which forms a wall of the working chamber (4) of solely one rotor, preferably the male rotor (2).