A port plate assembly of a hydraulic unit includes a port plate and a journal bearing. The port plate includes a fixed-speed interface side having a fixed-speed interface surface, and a variable-speed interface side having a variable-speed interface surface. A plurality of kidney-shaped apertures is defined at a kidney pitch diameter about a central bore of the port plate between the fixed-speed interface surface and the variable-speed interface surface. The port plate also includes control cylinder interface formed at a control cylinder radial offset from a central axis of the central bore, where a ratio of the control cylinder radial offset to the kidney pitch diameter is between 1.629 and 1.639. The journal bearing is installed in the central bore of the port plate, where the journal bearing provides an interface for a fixed-speed shaft and a variable-speed shaft of the hydraulic unit.

A coolant pump assembly having a combined hydraulic drive pump and a coolant circulating pump is disclosed herein, for use in connection with a utility vehicle, such as a ride-on or stand-on mower. Such a vehicle includes at least one combination pump assembly that utilizes a first fluid circuit to hydraulically drive a wheel of the vehicle and a second fluid circuit to cool one or more vehicle components.

A method is provided for forming wear-resistant layer on the surface of cylinder bores a cylinder drum of a hydrostatic axial piston machine within which a respective piston is moved in a manner subject to intensive wear. The cylinder bores are gas nitrocarburized in two stages to minimize the wear and include a thin uniform connecting layer that has a thickness of 4 to 16 μm and a comparatively thick underlying diffusion layer.

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 swash-plate type piston pump includes a cylinder block configured to be rotated with rotation of a driving shaft, a plurality of pistons accommodated in a plurality of cylinders provided in the cylinder block, a swash plate configured to reciprocate the piston so that a volume chamber of the cylinder is expanded/contracted with the rotation of the cylinder block, an biasing mechanism configured to bias the swash plate in a direction where a tilting angle is made larger, a control pin configured to drive the swash plate in a direction where the tilting angle is made smaller in accordance with a rise in a load pressure of a pressure chamber, and a discharge channel configured to discharge the load pressure of the pressure chamber.

A hydraulic machine with oscillating axial cylinders includes a plurality of oscillating axial cylinders, put in synchronous rotation between a first rotating element, a rotating disc, which supports one end of the cylinder, bottom or piston, and a second rotating element, a rotating barrel, which supports the opposite end of the cylinder; each cylinder is connected to said rotating elements with a ball joint towards each of them; each ball joint is holed to allow for the passage and the feeding/discharge through it of the hydraulic liquid. At least the bottom or the piston is connected to the respective rotating element with a ball joint having a spherical surface with a diameter equal to or greater than the cylinder bore.

A housing of an axial piston device is provided with a drain port for discharging the retained oil to the outside and a supply oil passage for guiding lubricating oil, which has been supplied from an oil source, toward a first hydraulic axial piston member. The drain port is arranged so as to bring about such a retained-oil level that a second hydraulic axial piston member, which is disposed below the first hydraulic axial piston member, is partially or entirely immersed in the retained oil while the first hydraulic axial piston member is not immersed in the retained oil.

A housing of an axial piston device is provided with a drain port for discharging the retained oil to the outside and a supply oil passage for guiding lubricating oil, which has been supplied from an oil source, toward a first hydraulic axial piston member. The drain port is arranged so as to bring about such a retained-oil level that a second hydraulic axial piston member, which is disposed below the first hydraulic axial piston member, is partially or entirely immersed in the retained oil while the first hydraulic axial piston member is not immersed in the retained oil.

An axial piston pump has a fluid inlet, a fluid outlet, and a rotatable, one-piece piston housing carrying one or more pistons movable within one or more respective sleeves formed by the housing. A circumferential row of fixed field members is mounted to the housing at a mounting location formed by the housing, the mounting location being radially outward of the sleeve(s). The pump further has a stator surrounding the piston housing and including a circumferential row of armature windings such that the piston housing and the stator form an electro-magnetic motor operable to rotate the piston housing, and a swashplate engaged with the piston(s) such that rotation of the piston housing relative to the swashplate around an axis of rotation produces reciprocating movement of the piston(s) for the pressurisation of fluid received into the sleeve(s) from the fluid inlet and then discharged from the sleeve(s) to the fluid outlet.

An axial piston pump has a fluid inlet, a fluid outlet, and a rotatable, one-piece piston housing carrying one or more pistons movable within one or more respective sleeves formed by the housing. A circumferential row of fixed field members is mounted to the housing at a mounting location formed by the housing, the mounting location being radially outward of the sleeve(s). The pump further has a stator surrounding the piston housing and including a circumferential row of armature windings such that the piston housing and the stator form an electro-magnetic motor operable to rotate the piston housing, and a swashplate engaged with the piston(s) such that rotation of the piston housing relative to the swashplate around an axis of rotation produces reciprocating movement of the piston(s) for the pressurisation of fluid received into the sleeve(s) from the fluid inlet and then discharged from the sleeve(s) to the fluid outlet.