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.

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 hydrostatic axial piston machine includes a double-acting actuating cylinder configured to adjust the piston displacement. The actuating cylinder has two actuating chambers that are connected to two spatially separated cartridge valves. The two cartridge valves are inserted obliquely into a wall section of the axial piston machine. The wall section on the one hand forms a wall of the housing of the axial piston machine and on the other hand forms a wall of the actuating cylinder.

A bent-axis axial-piston hydraulic machine may have a cylinder block being movable circumferentially about a first rotation axis. The machine may also have a transmission shaft which is functionally associated with the cylinder block and which can rotate about a transmission axis incident on the rotation axis. The machine may also have a distributor, and a device for angular offsetting which is associated with the distributor to rotate the distributor to cause a variation of effective cubic capacity while a geometric cubic capacity of the machine remains constant. The corresponding method for adjusting the capacity of a bent-axis axial piston hydraulic machine is also disclosed.

A rotary hydraulic machine with radial pistons comprising: a rotating shaft (2); a cylinder-housing body (3), having a plurality of housing seatings (4) arranged radially at equal distances from the rotation axis (R) of the rotating shaft (2); a cylinder (5) housed in each of said plurality of housing seatings (4) and rotating relative to the same around an axis (C) concentric with said rotation axis (R) of the rotating shaft (2); a piston (6) slidable in each cylinder (5) and coupled to a crank (7) of the rotating shaft (2); a supply conduit (12), for each cylinder (5), provided with a seal (120) arranged to enable a sealed connection between the supply conduit (12) and the respective cylinder (5). Each seal (120) comprises: a first ring (121), arranged at an end of the supply conduit (12) and placed in contact with the cylinder (5); a second ring (122), concentric to the first ring (121) and interposed between the supply conduit (12) and the first ring (121), wherein the second ring (122) is coupled by interference with the first ring (121) and is inserted by interference into the supply conduit (12) in such a way as to prevent a rotation of the first ring (121) with respect to the supply conduit (12) around a common axis (X).

The present invention relates to a method of manufacturing a drum of an axial piston machine by machining a cylindrical round metal, with the machining comprising a forging and with at least one structural element of the drum being produced or prefabricated by the forging.

An axial piston machine may include a rotor rotatably mounted in a housing. A plurality of cylinders may be arranged in a ring around the rotor. A plurality of pistons may each be arranged within each of the plurality of cylinders and may be constructed and arranged to selectively translate within the plurality of cylinders. A plurality of inlet openings may be defined in a cylinder head and at least one outlet opening may be defined in the housing. The plurality of cylinders may be in operative communication with the plurality of inlet openings and the at least one outlet opening. An inlet channel may be defined in the cylinder head and may extend to each of the plurality of inlet openings. An outlet channel may be defined in the housing and may be in operative communication with the at least one outlet opening. A bypass channel may be defined in the housing and may extend from the cylinder head into one of the outlet channel or a swashplate space. A bypass valve may be connected to the cylinder head or may be integrated with the cylinder head. The bypass valve may be constructed and arranged to selectively apportion a working medium to the inlet channel and the bypass channel based on a switching position of the bypass valve.

A variable displacement pump-motor includes a pump-motor having a plurality of cylinders and pistons, and further including a main shaft rotatable relative to the system body. A hydro mechanical control system includes a plurality of main stage valves in communication with the plurality of cylinders. Each of the main stage valves is configured to open and close a cylinder of the plurality of cylinders to one or more of high or low pressure fluid sources. A pilot spool valve is in selective communication with each of the main stage valves. The pilot spool rotates with the main shaft. The pilot spool includes coding configured to operate each of the main stage valves to open and close the respective cylinders to the one or more high and low pressure fluid sources according to a translational position of the pilot spool and rotation of the pilot spool by the main shaft.

The devices comprises a distributor (16) that presents distribution ducts opening out into a radial distribution face (16A), and a distributor-counterpart engaged in each other in such a manner that two main enclosures (18, 20) are provided between their opposite axially-extending faces. The device comprises a cylinder-capacity selector comprising two slides (24, 26) arranged after the other in a bore (22) of the element engaged in the other, to which are connected the main enclosures (18, 20) and at least some of the distribution ducts (30, 31). The slides are able to adopt at least three distinct configurations establishing different connections between the main ducts (18, 20) and the distribution ducts via the main enclosures, in order to be able to obtain at least three distinct operating cylinder capacities.

An axial piston machine may include a rotor with a shaft. A plurality of cylinders may be arranged in an annular manner about the shaft. A plurality of pistons may each be positioned within each of the plurality of cylinders and may be constructed and arranged to move translationally within the plurality of cylinders. A cylinder head may include a plurality of inlet openings and may be in operative communication with the plurality of cylinders. A sealing washer having a plurality of passage openings may be disposed on the cylinder head so that the plurality of passage openings and the plurality of inlet openings may be flush with one another. A number of the plurality of inlet openings may correspond to a number of the plurality of passage openings. A valve plate may be connected to the shaft in a rotationally fixed manner and may be constructed and arranged to be brought into congruence with the plurality of passage openings of the sealing washer based on a rotary angle. The sealing washer may be disposed between the plurality of inlet openings and the valve plate and may be prestressed against the cylinder head and onto the inlet openings.