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 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 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 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 pump with a motor includes a pump housing, a motor housing, and a connecting structure configured to connect the motor housing to the pump housing. The connecting structure includes a motor connecting portion provided at an end of the pump housing, and a pump connecting portion provided at an end of the motor housing. The motor connecting portion includes a bearing configured to rotatably support the other end of the rotating shaft whose one end supported by the motor housing, a plurality of through holes, and projections projecting to the side of the motor housing. The pump connecting portion includes a first hole in which the bearing is fitted, a plurality of connecting pieces inserted into the plurality of through holes, respectively, and caulked on the motor connecting portion, and second holes in which the projections are fitted.

A pump with a motor includes a pump housing, a motor housing, and a connecting structure configured to connect the motor housing to the pump housing. The connecting structure includes a motor connecting portion provided at an end of the pump housing, and a pump connecting portion provided at an end of the motor housing. The motor connecting portion includes a bearing configured to rotatably support the other end of the rotating shaft whose one end supported by the motor housing, a plurality of through holes, and projections projecting to the side of the motor housing. The pump connecting portion includes a first hole in which the bearing is fitted, a plurality of connecting pieces inserted into the plurality of through holes, respectively, and caulked on the motor connecting portion, and second holes in which the projections are fitted.

A hydraulic unit includes an assembly with a hydrostatic positive displacement pump and an electric motor. The positive displacement pump includes a driving shaft configured to be driven by the electric motor. The hydraulic unit also includes an inert mass on which the assembly is rigidly mounted so as to minimize vibration of the assembly and reduce noise emission from the assembly.

An electro hydrostatic actuator comprises a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator. The pump comprises an inlet and an outlet for the hydraulic fluid and an active flow path arranged therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path arranged to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet.

An electro hydrostatic actuator comprises a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator. The pump comprises an inlet and an outlet for the hydraulic fluid and an active flow path arranged therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path arranged to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet.

A pump module and a device for producing a fluid jet with a pump module are disclosed. In an embodiment the pump module may include a pump housing in which at least one pump piston is mounted in a reciprocatingly movable manner and is provided with at least one sealing element which during a pumping operation interacts with a cylinder. For creating such a pump module producible in a simple manner and nevertheless exhibiting the functionality necessary for the pumping operation, embodiments disclose a valve block, which receives at least one valve associated with the cylinder, wherein the cylinder is sealed against the valve block. Furthermore, a cover element may abut against the valve block on a side opposite to the cylinder and between itself and the valve block forms an inlet passage leading to the cylinder and/or an outlet passage communicating with the cylinder.