A positive displacement pump assembly includes a rotor housing defining a rotor cavity, and an end plate configured to at least partially close one end of the rotor cavity. Rotors are supported on and fixed to rotor shafts and extend through the rotor cavity. A first pair of bearings fixing the rotor shafts to the end plate. A second pair of bearings fixes the rotor shafts to the rotor housing, preventing relative axial movement between the rotor shafts and the rotor housing. The end plate is axially movable with the rotor shafts when the rotor shafts vary in axial length due to thermal fluctuations so that changes in an axial clearance at end faces of the rotors are reduced.

A transfer device that includes a case that houses a transfer mechanism; a strainer that suctions oil stored in a lower portion of the case; a valve body that has a hydraulic supply circuit that supplies a hydraulic pressure to the transfer mechanism and a suction oil path that discharges an extra hydraulic pressure that is extra for the hydraulic supply circuit; a first suction inlet that communicates with one of the suction oil path and the strainer and a second suction inlet that communicates with the other of the suction oil path and the strainer, and a balanced vane pump.

Durability of a vacuum pump is prevented from degrading by suppressing abrasion of a rotor and a side plate. The vacuum pump has a hollow cylinder chamber S having an opening at an end portion of a casing body, a rotor which is rotationally driven in the cylinder chamber S, a side plate for blocking the opening of the cylinder chamber S, and a pump cover which is disposed at the opposite side to the rotor so as to sandwich the side plate between the pump cover and the rotor, and the side plate is provided with an intercommunication port which confronts a shaft hole of the rotor and intercommunicates with a space between the side plate and the pump cover.

A back pressure space of a vane groove having completed communication with an intermediate-pressure supply groove communicates with a first supply section until refrigerant pressure in each of compression chambers having been partitioned by vanes of the vane grooves reach the highest pressure, and then high pressure is supplied from the first supply section. At a time point when the back pressure space having completed communication with an intermediate-pressure supply groove communicates with the first supply section of a high-pressure supply groove, the preceding back pressure space adjacent to that back pressure space on the downstream side of the rotation direction completes communication with the first supply section.

First closing plate and second closing plate close opening portions at both ends of cylindrical member in an axial direction. Base is housed in a space formed by cylindrical member, first closing plate, and second closing plate, and rotates around an axis in the same direction as the axial direction of cylindrical member. Resin layers are formed on thrust surfaces of base. Groove C is a plurality of concentric circular grooves or a spiral groove formed on each resin layer, and the center of circles of the circular grooves or the center of a spiral of the spiral groove is different from the rotation center of base.

A screw spindle pump having a spindle housing, in which a drive spindle and at least one running spindle which meshes therewith are received in spindle bores, an outer housing which encloses the spindle housing, and a cover component which is placed axially onto the outer housing and on which both an axial fluid inlet port and a lateral fluid outlet port are provided, wherein the fluid inlet port communicates with a fluid inlet of the spindle housing and the fluid outlet port communicates with a fluid outlet of the spindle housing, wherein the cover component is fastenable to the outer housing in a plurality of marked rotational positions with a first pitch, and wherein the spindle housing is fastenable to the cover component and/or in the outer housing in a plurality of marked rotational positions with a second, smaller pitch.

A rotary fluid machine that reduces fluid leakage from a gear pump or gear motor and achieves improvement in responsiveness is provided. The present invention is configured such that force of pressing a side plate toward gears by a seal member provided between the side plate and a case and performing pressure compartment is partly strong, not uniform along the entire length of the seal member. Specifically, for example, a gear pump comprises an assembly including a pair of gears, a side plate sealing a side surface of the gears, and a seal block sealing tooth tips of the gears, a case housing the pump assembly, and a seal member being arranged between the side plate or the seal block and the case and along a notch portion formed in the side plate or the seal block. The seal member is wider at a portion in a position passing through a place with large pressure fluctuations than at other portions.

A gear pump includes a pair of gears having meshed teeth. One of the gears is configured for connection to a source of drive. The gears are received within a housing. The housing has an inlet port configured for connection to a source of fluid and an outlet port. Each of the gears have a shaft rotating within the housing on a bearing on each axial side of each gear. At least one of the bearings associated with each of the pair of gears has a plurality of springs received in recesses to bias the said at least one bearing against an end face of a respective one of the pair of gears. A retention plate holds each of the plurality springs. A method of assembly is also disclosed.

A screw spindle pump, including a housing and a drive spindle accommodated therein and at least one running spindle which meshes with the latter and which has in each case two terminal end surfaces. A stop surface is provided axially adjacent to at least one end surface of the running spindle, wherein the running spindle is accommodated displaceably with an axial clearance perpendicular to the stop surfaces.

In a rotary compressor, a lower end plate cover is formed in a flat plate shape, a lower discharge chamber concave portion is formed in a lower end plate to overlap a lower discharge hole side of a lower discharge valve accommodation concave portion, and the lower discharge chamber concave portion is formed in a fan-like range between a diametrical line passing through a center of a sub-bearing unit and a midpoint of a line segment connecting a center of the lower discharge hole and a center of a lower rivet to each other and a diametrical line opened by a pitch angle 90° in a direction of the lower discharge hole about the center of the sub-bearing unit. At least a portion of a refrigerant path hole overlaps the lower discharge chamber concave portion and is disposed at a position communicating with the lower discharge chamber concave portion.