A hydraulic pump/motor includes: a cylinder block rotating about a rotation axis; a piston in a cylinder bore; and a valve plate facing a cylinder port. The valve plate includes: a high pressure port through which hydraulic oil discharged from the cylinder port flows; a low pressure port through which the oil to be sucked into the cylinder port flows; a region disposed between the high and low pressure ports in a circumferential direction of the rotation axis and including a top dead center position facing the cylinder port of the cylinder bore in which the piston moved to a top dead center is disposed; and a residual pressure release port between the top dead center position and the low pressure port in the region. The residual pressure release port includes first and second ports disposed at a positions different from each other in the radial direction of the rotation axis.

An axial piston device includes a cylinder block 11 rotatable integrally with a rotary shaft and having a plurality of cylinder chambers in a region surrounding the rotary shaft; a plurality of pistons 12 each contained in a corresponding one of the plurality of cylinder chambers; and a support configured to position respective protruding ends of the plurality of pistons; the cylinder block 11 has a plurality of cylinder ports 17 each continuous with a corresponding one of the plurality of cylinder chambers, and the plurality of cylinder ports 17 each have a central point T corresponding to the center of gravity in a cross section of a flow path at the cylinder port 17 and are, as viewed along the axis X, adjacent to one another along an imaginary circle C around the axis.

An axial piston device includes a cylinder block 11 rotatable integrally with a rotary shaft and having a plurality of cylinder chambers in a region surrounding the rotary shaft; a plurality of pistons 12 each contained in a corresponding one of the plurality of cylinder chambers; and a support configured to position respective protruding ends of the plurality of pistons; the cylinder block 11 has a plurality of cylinder ports 17 each continuous with a corresponding one of the plurality of cylinder chambers, and the plurality of cylinder ports 17 each have a central point T corresponding to the center of gravity in a cross section of a flow path at the cylinder port 17 and are, as viewed along the axis X, adjacent to one another along an imaginary circle C around the axis.

A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

A hydrostatic axial piston machine includes a pressing pressure chamber for the cylinder drum which is supplied with pressing pressure from a circular-arc-like elongate hole of a distributor plate or from a plurality of connection channels of the cylinder drum. The pressing pressure chamber is delimited radially outwardly by the cylinder drum and radially inwardly by the drive shaft. The pressing pressure chamber is delimited axially at both sides by seals which are both arranged between the radially inner rotating drive shaft and a radially outer stationary component. The radially outer component may be the cylinder drum or, in the case of the distributor-plate-side seal, also a gap seal between the drive shaft and a bearing bush of the distributor plate. Both seals are arranged at the distributor plate side with respect to a tooth arrangement or a retraction ball.

Multiport pumps and associated pumping systems are described that provide a selective hydraulic or electrically powered pump/pump system. The pumps provide movement within a device or larger system. Movement can cause compression/expansion of a fluid and provide fluid movement within the same device or system. In this instance, the volume of fluid and the fluid flow path within, from, and to the pump(s) is kept constant to reduce or eliminate cavitation, seizure, and/or hydraulic lock. Use of at least one reservoir comprising; a compensator tank, a port allowing for operation at ambient pressure, and a pressure measuring device measuring pressure allowing for unbalanced flow to and from the multiport pumps along with thermal expansion or compression is detailed. In addition, use of a multiport swashplate pumps and associated valve plates that incorporate the features and functions of several valves not heretofore provided within the pump itself is also described.

Multiport pumps and associated pumping systems are described that provide a selective hydraulic or electrically powered pump/pump system. The pumps provide movement within a device or larger system. Movement can cause compression/expansion of a fluid and provide fluid movement within the same device or system. In this instance, the volume of fluid and the fluid flow path within, from, and to the pump(s) is kept constant to reduce or eliminate cavitation, seizure, and/or hydraulic lock. Use of at least one reservoir comprising; a compensator tank, a port allowing for operation at ambient pressure, and a pressure measuring device measuring pressure allowing for unbalanced flow to and from the multiport pumps along with thermal expansion or compression is detailed. In addition, use of a multiport swashplate pumps and associated valve plates that incorporate the features and functions of several valves not heretofore provided within the pump itself is also described.

A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

A hydraulic engine with hydraulic pumps that moves the oil filled in the body thereof through the hydraulic pumps to allow rotational load bodies to be driven by means of the reciprocation of pistons, thereby obtaining a rotational force required for driving, includes: a power supply adapted to supply power to a driving part and to charge the power generated from rotational load bodies through the driving of a power driving part; the driving part driven through the power supplied from the power supply; a pair of hydraulic pumps adapted to pump a fluid through the rotation of the driving part; and the power driving part adapted to generate a driving force through the reciprocation of a driving piston.

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.