The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor (1). A spherical section (8b) is integrally formed on the swash plate-side end surface of a tilt piston (8), and a groove (10) into which the spherical section (8b) is fitted in a slidable manner is formed in the support surface (7b) (second support surface (7b2)) of the swash plate (7). The groove (10) is a part of the second support surface (7b2) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots (11).

The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor (1). A spherical section (8b) is integrally formed on the swash plate-side end surface of a tilt piston (8), and a groove (10) into which the spherical section (8b) is fitted in a slidable manner is formed in the support surface (7b) (second support surface (7b2)) of the swash plate (7). The groove (10) is a part of the second support surface (7b2) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots (11).

The invention relates to a displacement unit (1) of a hydraulic machine, for which the hysteresis is reduced. For this purpose, in the control spool (3) and/or at the control spool (3) a mass body (16) and a spring (17) are arranged, which are excited to resonance vibrations. The vibrations are self-excited and sustained by a partial flow rate of the hydraulic fluid which is modulated periodically. The high frequent vibrations are transmitted over the spring (17) onto the associated control spool (3), thereby reducing the friction and hence the hysteresis.

The invention relates to a displacement unit (1) of a hydraulic machine, for which the hysteresis is reduced. For this purpose, in the control spool (3) and/or at the control spool (3) a mass body (16) and a spring (17) are arranged, which are excited to resonance vibrations. The vibrations are self-excited and sustained by a partial flow rate of the hydraulic fluid which is modulated periodically. The high frequent vibrations are transmitted over the spring (17) onto the associated control spool (3), thereby reducing the friction and hence the hysteresis.

A port plate for a swashplate type axial piston pump is described herein. The port plate includes an inlet port, a discharge port, and a first metering notch in fluidic communication via a first passage with a metering notch area adjustment valve configured to adjust the effective area of the metering notch. The first metering notch is disposed at a leading edge of one of the inlet port or the discharge port.

A pump-regulator combination includes first and second pumps, a control valve, first orifice, and pilot valve. The first pump is configured to pump fluid from a tank to a first point. The control valve is configured to control pressure and/or delivery flow at the first point by adjusting a displacement volume of the first pump. The second pump is configured to pump fluid from the tank to a second point, through the first orifice, and back to the tank. A highest load pressure of the actuator is connected to a third point. The pilot valve includes an adjustable second orifice connected to the third point, via a fourth point, and the tank to pass fluid from the actuator to the tank. A pressure at the second point acts to close the second orifice. A pressure of the fourth point acts to adjust the control valve.

A hydrostatic axial piston machine includes a housing and a pivot cradle. At least one slide bearing of the pivot cradle on a high-pressure side is hydrostatically relieved. The slide bearing includes one or two pairs of relief grooves. A relief pressure field develops about and between the one or two pairs of relief grooves as the grooves are supplied with relief pressure medium on one side and are closed at their outer ends. An optional slide bearing on a low-pressure side has one or two limiting grooves which delimit the relief pressure field there, as the limiting grooves are open at their outer ends.

A variable displacement swash plate type piston pump includes first and second housing members fastened to each other by fastening members, a rotary shaft, a swash plate. A section of the inner circumferential surface of the first housing member has a recess. A bulging portion is arranged in a section of the outer circumferential wall of the first housing member. A section of the outer circumferential wall of the second housing member has a closing portion that closes the opening of the recess. The fastening members include first and second fastening members arranged at positions that are on the opposite sides of the recess, inside the width of the swash plate in a direction along the inclination axis of the swash plate, and closer to the rotary shaft than the distal ends of the bulging portion and the closing portion in the bulging direction.

An electroproportionally controlled differential pressure valve cartridge includes actuation and tank ports on an outer circumference, and a pump port on a face-side. A spring preloads a piston into a position that relieves pressure from the actuation port to the tank port. A current increase through an electromagnet opposite the pump port and a pressure increase at the pump port counter the spring to open a connection from the pump port to the actuation port. A concentric opening extends from the pump port to a first piston surface. A duct extends from the first piston surface to a pump chamber. A further duct extends from the pump port to a spring chamber between the pump chamber and electromagnet. In the spring chamber, pressure over a second piston surface counters pressure over the first piston surface.

A bent-axis machine comprises a housing having a control cover and a piston drum which is rotatably mounted in the housing on a valve plate and which has axial cylinders, each of which receives a piston. An adjustment system includes a pivot cradle via which the piston drum and the valve plate can be pivoted relative to the drive axis about a maximum working range which is delimited by a minimum pivot angle and a maximum pivot angle. The minimum pivot angle of the working range is shifted out of its zero position by at least 5, and the maximum pivot angle is extended in the same way by at least 5 in order to retain the entire working range about the region left out of the lower region.