Systems and methods are provided for pumps that deliver optimized torque characteristics and volumetric efficiency. A system includes a housing defining a surface and a rotor defining a face. A face clearance is defined between the face and the surface. The face clearance is variable in magnitude and determinative of target performance characteristics of the pump system. The housing is made of a material selected to have a thermal expansion characteristic and the rotor is made of a second material selected to have another thermal expansion characteristic. The thermal expansion characteristics deliver the target performance characteristics of the pump system.

A low pressure gear pump and wear plate is disclosed. The wear plate may comprise a sidewall, a drive portion, a driven portion, and a transition portion. The sidewall is free of a sealing member or a recess configured to receive the sealing member. The drive portion includes a drive inlet lip, a drive outlet lip, a drive recessed trough and a drive bore. The drive bore is configured to receive the drive shaft of the gear pump. The driven portion may that include a driven inlet lip, a driven outlet lip, a driven recessed trough, and a driven bore. The driven bore is configured to receive the driven shaft of the gear pump. The transition portion may include a transition aperture configured to receive a first fastener configured to mount the wear plate to the gear housing. The wear plate is made of bronze, aluminum or non-magnetic material.

An example crescent seal assembly comprises: an outer crescent of a gear pump; an inner crescent of the gear pump mating with the outer crescent such that an exterior peripheral surface of the inner crescent interfaces with an interior peripheral surface of the outer crescent, forming: (i) a spring cavity, (ii) a first check valve cavity, and (iii) a second check valve cavity therebetween; a spring disposed in the at least one spring cavity; a first check pin disposed in the first check valve cavity; and a second check pin disposed in the second check valve cavity.

An example assembly comprises: a pump cover; a thrust plate configured to interface with the pump cover at a first side of the thrust plate and interface with gears of a gear pump at a second side of the thrust plate; and a seal disposed within a seal cavity formed at an interface between the thrust plate and the pump cover, wherein the seal defines multiple partitions at the interface between the thrust plate and the pump cover and seals each partition of the multiple partitions from other partitions.

A gear bearing structure for an external gear pump includes a driving gear and the driven gear accommodated rotatably in a pump body of the external gear pump, an inlet chamber formed on one side of a mesh portion of the driving gear and the driven gear, an outlet chamber formed on the other side of the mesh portion, a hollow cylindrical bushing for holding a rotational shaft of the driving gear or the driven gear with a lubricating liquid film formed between itself and the rotational shaft, and a ring plate spring disposed between the pump body and the bushing to urge the bushing so as to slidably contact with a side face of the one of the driving gear and the driven gear.

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 transfer pump configured to move a hydraulic fluid in a hydraulic fluid management system of a hydraulic system of a vehicle including a transmission. In one embodiment, the transfer pump moves the fluid from a differential case to a hydraulic reservoir coupled to the transmission. The transfer pump is a positive displacement pump including an unloading device, such as a sealing plate, that is resiliently biased against the pump during a normal operation but is moved away from the pump upon the application of a pilot pressure. The result is an open chamber for the pump gears to turn without developing pressure, to thereby reduce parasitic losses.

A gear pump or a gear motor includes a casing, a helical drive gear, a helical driven gear, a drive-side space, and an idler-side space. The drive and driven gears mesh with each other in the casing to partition inside of the casing so as to include high and low pressure spaces. The drive-side and idler-side spaces are each configured to allow pressure therein to become higher than a pressure in the low-pressure space. The drive-side space faces an end portion of a drive shaft rotatably supporting the drive gear. The idler-side space faces an end portion of an idler shaft rotatably supporting the driven gear. The end portion of the drive shaft is pushed in a predetermined direction by working fluid supplied to the drive-side space. The end portion of the idler shaft is pushed in the predetermined direction by working fluid supplied to the idler-side space.

A sealing arrangement between a rotating plane surface on a rotor and a machine housing prevents flow of process fluid between an internal volume and an external volume of the machine housing. The sealing arrangement includes a piston arrangement, and a sealing bearing ring between the piston arrangement and the rotating plane surface. A fluid supply line supplies pressurized lubrication fluid through the machine housing to a piston cavity, wherein the piston arrangement further includes piston fluid channels and the bearing sealing ring includes lubrication conduits through the bearing sealing ring, corresponding with the piston fluid channels. The pressurized lubrication fluid is arranged for moving the piston arrangement against the sealing bearing ring and thus moving the sealing bearing ring against the sealing surface thus forming a sealing arrangement.