A piston and piston rod assembly includes a piston rod having a first portion and a smaller second portion extending from the first portion. The second portion has a circumferential groove that receives at least one sealing ring or O-ring located between the first portion and the free end of the second portion. A piston has an aperture extending between two ends, with the top open end having a larger diameter than the bottom open end. The second portion of the piston rod is inserted through the aperture of the piston so that the free end of the second portion emerges through the top open end of the piston and compresses the at least one sealing ring or O-ring with the inner surface of the piston. The free end of the second portion of the piston rod is cold-worked to overlie at least a portion of the top open end of the piston.

In the hydraulic pump according to the present invention, a straight path among the paths, through which the fluid flows within the hydraulic pump, and a connection point on the straight path are formed to have curvatures, so that it is possible to prevent stress from being concentrated to the connection point, thereby improving durability, and it is possible to manufacture the hydraulic pump by forming a casting shape with a curvature in advance, thereby decreasing additional machining and decreasing costs of a product.

In the hydraulic pump according to the present invention, a straight path among the paths, through which the fluid flows within the hydraulic pump, and a connection point on the straight path are formed to have curvatures, so that it is possible to prevent stress from being concentrated to the connection point, thereby improving durability, and it is possible to manufacture the hydraulic pump by forming a casting shape with a curvature in advance, thereby decreasing additional machining and decreasing costs of a product.

In an embodiment, a pump assembly may include a mounting structure and a pump mechanism and a starter motor coupled to the mounting structure. The pump mechanism may include an input shaft configured to be rotatably coupled with an output shaft of a prime mover engine. The starter motor may be coupled with the input shaft of the pump mechanism for rotatably driving the input shaft of the pump mechanism.

An axial piston pump has a rotor rotatable around an axis relative to a swashplate; one or more pistons movable within one or more respective sleeves; a fluid inlet port for the inflow of low pressure fluid, and a fluid outlet port for the outflow of high pressure fluid; and a floating element axially positioned between, on the one side, the inlet and outlet ports and, on the other side, a sealing surface of the rotor. Surfaces of the floating element defining an inlet chamber and the outlet chamber are configured such that, in use, the low pressure fluid and the high pressure fluid act on the defining surfaces to produce a net axial force which the axially slidable floating element applies to the rotor to seal the floating element to the sealing surface of the rotor.

A pump for cryogenic liquids including plurality of temperature managed pumping mechanisms. Each pumping mechanism including a barrel having a first end and a second end, and at least one bore extending through the barrel from the first end to the second end. The pump barrel including a stabilizer positioned on the first end and at least partially defining a space in fluid communication with the at least one bore to provide cooling to the barrel.

Some of the present systems include a hydraulic power storage system having an accumulator configured to supply pressurized hydraulic fluid to a hydraulically actuated device to actuate the hydraulically actuated device and a drain in fluid communication with the accumulator and including a valve that is actuatable to drain hydraulic fluid from the hydraulic power storage system such that an internal pressure of the accumulator is reduced and a flow restrictor configured to reduce a flow rate of hydraulic fluid through the valve, a hydraulic pump configured to pressurize the accumulator, a pressure sensor configured to capture data indicative of the internal pressure of the accumulator, and a processor configured to actuate the hydraulic pump to increase the internal pressure of the accumulator if the internal pressure of the accumulator, as indicated in data captured by the pressure sensor, falls below a threshold pressure.

Some of the present systems include a hydraulic power storage system having an accumulator configured to supply pressurized hydraulic fluid to a hydraulically actuated device to actuate the hydraulically actuated device and a drain in fluid communication with the accumulator and including a valve that is actuatable to drain hydraulic fluid from the hydraulic power storage system such that an internal pressure of the accumulator is reduced and a flow restrictor configured to reduce a flow rate of hydraulic fluid through the valve, a hydraulic pump configured to pressurize the accumulator, a pressure sensor configured to capture data indicative of the internal pressure of the accumulator, and a processor configured to actuate the hydraulic pump to increase the internal pressure of the accumulator if the internal pressure of the accumulator, as indicated in data captured by the pressure sensor, falls below a threshold pressure.

An axial piston pump may comprise a valve plate assembly including a plurality of valve plates rotatably disposed adjacent to each other and configured to control the flow of fluid between a piston chamber and inlet and outlet port passages. The piston pump may also comprise a swashplate arrangement that is capable of being angled in two different directions to be used in combination with the valve plate assembly. A fixed displacement axial piston pump may also comprise the valve plate assembly disclosed herein in which pressure transitions are facilitated in the same fashion, but without the variable of changing swashplate angles which control pump flow.

A pressure-maintaining valve arrangement of a purge circuit of a closed hydraulic circuit includes a pressure-maintaining valve configured to be shut off via a pilot valve. In one embodiment, a control pressure chamber, acting in the closing direction, of the pressure-maintaining valve is configured to be relieved via the pilot valve to a tank, and the pressure-maintaining valve is closed via a spring acting in the closing direction. In another embodiment, the valve arrangement includes an additional control pressure chamber acting in the closing direction. The additional control pressure chamber is configured to be loaded via the pilot valve, and the pressure-maintaining valve closes. The pressure of the inlet of the pressure-maintaining valve is used for this purpose.