A multi piston machine includes a rotor, pistons, a first control valve, and a second control valve. The pistons abut against a cam surface with multiple lobes. The machine is switchable between at least three non-zero displacement volumes using the first and the second control valves. The first control valve is connected to a first and a third fluid chamber. The second control valve is connected to a second and a fourth fluid chamber. The first and the second control valve are connected to first and the second working port respectively. A third number of second control openings is twice a second number of the lobes. There is a first and a second group of the second control openings. Adjacent second control openings belong to a different first or second group. The second control openings of the first group are either connected to the first or the second fluid chamber.

Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can have enhanced adjustability. An angle sensor for sensing the angular position of a pivot arm can have a housing, and the housing can be angularly adjustable about the pivot axis relative to the pivot arm.

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 radial piston motor comprises cylinder-piston units arranged in a star shape, a housing, an output shaft, an inner axial housing collar, an outer axial shaft collar, an output flange, an output shaft, and a brake positioned at least in certain sections between the inner axial housing collar and the outer axial shaft collar. The output flange is attached to the output shaft. The output flange is attached to the shaft collar radially outside the shaft collar.

The device comprises an internal distributor to be disposed in a casing portion (10A), and comprising a body (15) that has an outside axial face (15B) provided with two grooves (17, 19) respectively for feed and for discharge. The distributor has distribution ducts (23A, 23B, 23C) that open out in a distribution radial face and a cylinder capacity selector that comprises a slide (50) suitable for being moved in an axial bore (53) for connecting the distribution ducts to one or the other of the grooves. The device further comprises a control chamber (52) provided between a first end wall (15′) of the bore and the first end (50A) of the slide, and an opposing spring (55) disposed in a return chamber (52′) situated at the second end (53″) of the bore and closed, at the end closer to the distribution face (15A), by a second end wall (55′) of the distributor.

A hydraulic transmission circuit is provided having at least two elementary hydraulic motors, each having a secondary enclosure and a main duct for fluid feed and a secondary enclosure and a main duct for fluid discharge. A fluid distributor distributes fluid from the main ducts to the elementary motors via the secondary enclosures. A control system controls the elementary motors. Valves connecting the fluid distributor to the secondary enclosures of the first motor put a secondary enclosure into communication with a main duct independent of an operating mode of any other elementary motor.

A hydraulic device having a plurality of cylinders for distributing a flow of hydraulic fluid between a reservoir and a load, the device comprising: a housing having the plurality of cylinders with a plurality of corresponding pistons configured for reciprocation of a constant stroke length; an input port of the housing fluidly connected to each cylinder of the plurality of cylinders, the input port facilitating introduction of the hydraulic fluid into said each cylinder; an output port of the housing connected to said each cylinder, the output port facilitating the ejection of the hydraulic fluid from said each cylinder during the reciprocation, the output port configured for fluidly coupling said each cylinder to the load; and a distributor coupled to a main shaft of the hydraulic device, such that the distributor rotates in conjunction with the main shaft, the distributor having a distributor body including a first port configured for fluid communication with the input port and a second port configured for fluid communication with the output port; wherein the first port and the second port are fluidly coupled to the input port and the output port external to a shaft body of the main shaft.

A hydrostatic servo assembly unit (1) for being arranged inside, outside or distant from a variable displacement hydrostatic unit (100) and for controlling the displacement of the variable displacement hydrostatic unit (100). The servo assembly unit (1) includes a servo housing (10) in which at least one servo piston (40) is arranged. The piston head (42) of the servo piston (40) can be pressurized such that the servo piston (40) can move linear relative to a servo cylinder (12) formed in the servo housing (10). The servo assembly unit (100) further includes a movable output element (49) protruding outside of the servo housing (10), which can be mechanically coupled to a displacement element (102) of a variable displacement hydrostatic unit (100).

A hydraulic radial piston device includes a housing, a pintle having a pintle shaft, a rotor mounted on the pintle shaft and defining a plurality of cylinders, and a plurality of pistons displaceable in the cylinders. The radial piston device further includes a piston ring that provides an interface for the pistons. The radial piston device includes various configurations for improving the performance and efficiency of the device.

A hydrostatic positive displacement machine has an adjustable swept volume, and has a lifting element, a rotor with positive displacement elements supported on the lifting element, and a hydraulic adjusting device that adjusts the swept volume and includes an adjusting piston that is mounted in or on a cylinder, is movable axially rectilinearly in relation to the cylinder, and is adjacent to a pressurizable adjusting chamber. A bearing gap is formed between a circular-cylindrical bearing surface of the adjusting piston and a circular-cylindrical bearing surface of the cylinder. The adjusting piston is mounted hydrostatically, wherein at least three pressure pockets are distributed uniformly in a row over the circumference of a bearing surface. Pressure fluid flows into each pressure pocket via a fixed throttle, which is assigned only to the respective pressure pocket, and flows out of each pressure pocket via the bearing gap.