A bearing system for a compressor including an unloader at least partially received within a recess of a driveshaft. The unloader includes an outer surface that is engaged with a bearing. An inner surface of the unloader is curved such that the unloader is pivotable relative to the driveshaft unload forces on bearing caused by deflection of the driveshaft.

Tapered shafts for fluid pumps are disclosed. An example apparatus to pump fluid includes a gear, and a shaft including a taper to define a first portion of the shaft having a first thickness and a second portion of the shaft having a second thickness less than the first thickness, the second portion of the shaft between the gear and the first portion of the shaft.

A rotor for a multi-stage vacuum pump, a multi-stage vacuum pump and a method. The rotor comprises: a plurality of rotary vanes, the plurality of rotary vanes being axially displaced and coaxially aligned; a pair of end shafts, each end shaft extending from opposing axial ends of the plurality of rotary vanes; and an inter-vane shaft extending between adjacent rotary vanes of the plurality of rotary vanes, the inter-vane shaft having a diameter which is greater than that of the end shafts. In this way, the inter-vane shaft provided between each rotary vane may have an increased diameter, which improves the stiffness of the shaft and changes the modal frequency of the rotor. Such a change in the modal frequency is typically sufficient to improve its operation.

A bearing system for a compressor including an unloader at least partially received within a recess of a driveshaft. The unloader includes an outer surface that is engaged with a bearing. An inner surface of the unloader is curved such that the unloader is pivotable relative to the driveshaft unload forces on bearing caused by deflection of the driveshaft.

A liquid pump/motor combination powered by an electric motor, preferably, an oil pump or reducing-agent pump with an electric motor, a positive displacement pump and a bearing shield arranged between the electric motor and the positive displacement pump. The liquid pump/motor combination comprises a positive displacement pump; an electric motor; and a bearing shield having a contact face, the bearing shield arranged between the electric motor and the positive displacement pump. A spherical bearing is accommodated in the bearing shield, the spherical bearing, under application of a force, being able to swivel to a limited extent. A connecting shaft is accommodated in the spherical bearing. The connecting shaft is positioned between the electric motor and the pump. An annular bearing gap, filled with liquid, is between the inside diameter of the spherical bearing and the connecting shaft. The arrangement functions as a hydrodynamic sliding bearing.

A rotor unit for an eccentric screw pump, comprising a drive shaft which is drivable by means of a drive element of the eccentric screw pump, a helical rotor, and a flex shaft connecting the drive shaft to the rotor, wherein the flex shaft is at least in part accommodated within in the drive shaft, and wherein between the flex shaft and the drive shaft a gap extending around the flex shaft is provided, which allows for a radial movement of the flex shaft within the drive shaft.

An improved screw pump such as, for example, a twin screw pump is disclosed. In one embodiment, the screw pump includes a casing, first and second intermeshing rotors, and a liner positioned between the first and second rotors and the casing. In use, the liner is arranged and configured to bend and/or pivot in unison with the first and second rotors under the axial hydraulic pressure experienced by the screw pump during use. In one embodiment, the liner may be arranged and configured to include an asymmetric axial stiffness to facilitate bending of the liner. In another embodiment, the liner may be arranged and configured in multiple segments, the segments being arranged and configured to pivot to approximate the bending of the rotor shafts.

A bearing system for a compressor including an unloader at least partially received within a recess of a driveshaft. The unloader includes an outer surface that is engaged with a bearing. An inner surface of the unloader is curved such that the unloader is pivotable relative to the driveshaft unload forces on bearing caused by deflection of the driveshaft.

In the two-cylinder hermetic compressor, a main bearing is disposed on one surface of a first cylinder, an intermediate plate is disposed on another surface of the first cylinder, the intermediate plate is disposed on one surface of a second cylinder, and an auxiliary bearing is disposed on another surface of the second cylinder. A shaft is constituted by a main shaft portion which has a rotor attached thereto and is supported by the main bearing, a first eccentric portion having a first piston attached thereto, a second eccentric portion having a second piston attached thereto, and an auxiliary shaft portion supported by the auxiliary bearing. A thrust receiving portion is provided on a side of the second eccentric portion facing the auxiliary shaft portion, and the auxiliary bearing is provided with a thrust surface on which the end face of the thrust receiving portion slides while contacting therewith. The thrust surface is provided with a ring groove.

The oil-free screw compressor includes: a screw rotor including a screw and a shaft; a bearing; a first shaft seal device disposed between the screw and the bearing, the first shaft seal device including: a first seal and a first communication section configured to communicate the bearing side with respect to between the shaft and the first seal, and an outer peripheral face of the first shaft seal device; a second shaft seal device disposed between the first shaft seal device and the bearing, the second shaft seal device including: a second seal and a second communication section configured to communicate the screw side with respect to between the shaft and the second seal, and an outer peripheral face of the second shaft seal device; and a first seal member including a seal between the first communication section and the second communication section. The casing includes an atmosphere communication section configured to communicate the first communication section and the second communication section with an atmosphere. A sectional area in the first communication section is larger than a sectional area between the seal of the first seal member and the shaft.