It includes a plurality of cylinders formed on the cylinder block; a piston slidably inserted into the cylinder; a case accommodating the cylinder block; and a valve plate formed by a core member and a resin layer coating the core member, the valve plate being interposed between the cylinder block and an end cover of the case. The valve plate has a first land portion formed by the resin layer, the first land portion being in sliding contact with the cylinder block; and an outer-side non-contact portion provided closer to an outer side in a radial direction than the first land portion, the outer-side non-contact portion being separated away from the cylinder block. At least a part of the outer-side non-contact portion is an exposed portion where the core member is exposed.

The present disclosure relates to an adjusting device for adjusting the swash plate of an axial piston machine comprising an adjusting piston, which is connected to the swash plate of the axial piston machine via an adjusting lever, and a regulator for adjusting the adjusting pressure acting on the adjusting piston in dependence on a control force acting on a control piston of the regulator, wherein the adjusting piston is connected to the control piston via a feedback spring. In accordance with the present disclosure the feedback spring is at least partly received in a pot-shaped recess of the control piston.

A plunger pump fluid end assembly design in which the suction valve and seat is aligned with the plunger and the fluid end housing is constructed with multiple modules. Modules are held in a rigid assembly by staybolts that connect to the power end of the plunger pump. Said staybolts pass though bores in the central fluid module and the suction seat module and bound by a conventional threaded nut. Packing box modules are bound to the central fluid module by bolts that also pass through separate bores in the same central module. A suction valve spring retainer/plunger spacer within the plunger bore of the assembly shields the intersection of the plunger bore and the discharge bore from destructive erosion damage.

A hydraulic piston pump includes a reciprocal piston disposed in a blind housing bore of a piston housing to generate a pumping action. To accommodate the piston, a piston cartridge is installed in each of the housing bores. The piston cartridge includes a piston sleeve having an inner sleeve periphery, a first outer sleeve periphery, and a second outer sleeve periphery. The inner sleeve periphery is configured to establish sliding contact with the piston. The first outer sleeve periphery has a first outer sleeve diameter that is larger than a second outer sleeve diameter of the second outer sleeve periphery. To seal against the blind housing bore, a liner cap having a cylindrical liner wall and an axial liner cover is disposed over the first outer sleeve periphery. The axial liner cover abuts a housing bore ceiling of the blind housing bore and can receive hydraulic fluid there through.

A hydraulic pump assembly for a vehicle is provided, comprising an electrical motor, a hydraulic pump driven by the electrical motor, and a centrifugal regulator connected with a pressure overflow valve connected to the oil outlet of the hydraulic pump, characterized in that the pump assembly further comprises at least two input check valves and at least two output check valves arranged such that a first pressure outlet port is formed when the motor is rotating in a first direction, and a second pressure outlet port is formed when the motor is rotating in an opposite direction.

A cover, a fluid end and a plunger pump are provided. The cover includes: a body, the body being cylindrical, and the body including a first end, a second end, and a side surface connecting the first end and the second end; a main flow channel extending along an axis of the body; a plurality of subsidiary flow channels, each of the plurality of subsidiary flow channels being communicated with the main flow channel; a first opening, located at the first end and communicated with the main flow channel; and a plurality of second openings, located at the side surface of the body; each of the plurality of subsidiary flow channels being communicated with at least one of the plurality of second openings.

A cover, a fluid end and a plunger pump are provided. The cover includes: a body, the body being cylindrical, and the body including a first end, a second end, and a side surface connecting the first end and the second end; a main flow channel extending along an axis of the body; a plurality of subsidiary flow channels, each of the plurality of subsidiary flow channels being communicated with the main flow channel; a first opening, located at the first end and communicated with the main flow channel; and a plurality of second openings, located at the side surface of the body; each of the plurality of subsidiary flow channels being communicated with at least one of the plurality of second openings.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits that each comprise a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A piston drive assembly, including: a housing enclosing each of: a plurality of cylinders, each cylinder having an axis substantially parallel to the axis of the other cylinders; a plurality of pistons, one piston in each cylinder; a wobble plate connected to each of the plurality of pistons; a swashplate rotatably fixed to a drive shaft such that the drive shaft can rotate the swash plate or the swash plate can rotate the drive shaft, wherein the drive shaft extends through the entire length of the housing.

The systems, devices, and methods described herein describe a valve cover assembly that enables the easy removal and insertion of a screw gland into a threaded ring. The valve cover assembly includes an outside housing that provides an offset between a fluid end module and a top end of the valve cover assembly. A spring is positioned between the top end and the threaded ring and biased to provide a downward force on the threaded ring. The screw gland applies a reaction force against a valve plug. A piston is positioned at a base of the threaded ring in contact with the fluid end module. When actuated, the piston overcomes the downward force and lifts the threaded ring from the fluid end module. This reduces the force on the plug and allows a user to remove the screw gland by hand (and install as well) and without additional machinery required.