An axial piston machine may include a shaft and a housing surrounding at least a portion of the shaft. A cylinder arrangement may be disposed within the housing in a circular manner. The cylinder arrangement may include a plurality of cylinders and a plurality of pistons each extending within each of the plurality of cylinders and may be constructed and arranged to drive the shaft. The plurality of cylinders may each include an expansion volume with an inlet and at least one outlet opening for a working medium. A cylinder head may be provided on the housing and may be constructed and arranged to close the plurality of cylinders of the cylinder arrangement. A cavity may be defined around the shaft in a central region of the cylinder arrangement and may be in operative communication with a plurality of auxiliary outlet openings of the expansion volume of each of the plurality of cylinders via a temporary connection. A cylindrical roller slider may rotate within the cavity in the central region of the cylinder arrangement and may be constructed and arranged to drive the shaft. A temporary connection between the cavity and the expansion volume of each of the plurality of cylinders may be formed by at least one of a channel through the cylindrical roller slider and a recess on an outside surface of the cylindrical roller slider. The recess may extend laterally from a casing of the cylindrical roller slider at a height of the plurality of auxiliary outlet openings in each of the plurality of cylinders and at a distance to the cavity in the central region of the cylinder arrangement.

The invention relates to a device (10) for controlling the displacement of a machine (20) with axial pistons comprising a case (23) that houses a control unit comprising a displacement control spool (110) adapted to be switched between two positions by a control pressure (Ps) according to an axis of sliding (): a working position wherein the control spool (110) provides a connection between at least one inlet (103, 104) that receives a supply pressure and an outlet (105, 106) connected to a cylinder for adjusting the inclination of said machine (31a, 31b), and an idle position wherein the control spool (110) interrupts the connection between said inlet (102, 104) and said outlet (101, 103), and comprising means for switching adapted to vary the position of the adjusting cylinder (31a, 31b), a spring (140), characterised in that: said means of communication comprise a second switching spool (130), coaxial to the control spool (110), a switching pressure (Pm) exerts an axial force on the second spool (130) in the direction of the control spool (110), the spring (140) exerts an axial force on the two spools (110, 130), which tends to move them apart from each other, control pressure (Ps) exerts an axial force on the control spool (110) in the direction of the second tool (130).

A method for controlling torque equilibrium of a hydraulic motor, the method includes: setting a torque equilibrium reference position in a control system, setting a reference direction in the control system, determining one or more high-pressure torque producing cylinders towards the torque equilibrium reference position in a reference direction in the control system, and opening a high-pressure valve on each of one or more high-pressure torque producing cylinders to produce a torque towards the torque equilibrium reference position in the reference direction on the drive shaft of the motor.

A hydraulic machine comprising: an outer casing comprising a first front plate and a second front plate, a shaft rotatable about a main axis, a first rotor comprising a first rotor body rotatable with said shaft around said main axis, and a plurality of first pistons with respective spherical ring heads fixed to said first rotor body, a second rotor comprising a second rotor body and a plurality of second pistons with respective spherical ring heads, wherein the second rotor is rotatable about a secondary axis, inclined with respect to said main axis, a plurality of sleeves that are separate and independent from each other, each having a cylinder open at opposite ends and engaged on opposite sides by a first piston and by a second piston.

A hydraulic unit includes a driving mechanism whose displacement volume is adjustable to two operational states by means of a position-able adjustment element. The adjustment element can be positioned by a servo piston of a servo unit into a first, initial position and a second, operative position. A first front face and a second front face of the servo piston, which are opposing each other, can be pressurized individually with pressurized hydraulic fluid in order to position the servo piston at either end position of a servo cylinder of the servo unit. The servo piston is of a stepped design thereby forming a ring-shaped damping surface opposing the first front face. In the servo cylinder a ring-shaped shoulder surface is formed opposing the damping surface such that a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder.

A hydraulic radial piston device is provided with a mechanism for reducing pressure pulsations and providing a smooth pressure transition throughout different displacement operations. In certain examples, the hydraulic radial piston device is configured to maintain an amount of precompression and an amount of decompression of hydraulic fluid trapped in a cylinder chamber to be consistent, respectively, throughout different displacement operations.

A hydraulic machine (1) comprising first and second brake elements (92, 93), a spring washer (65) tending to urge the first and second brake elements (92, 93) in a braking direction, and a brake release piston (61) configured to act on the spring washer (65) in a direction opposing the braking direction, the hydraulic machine being characterized in that the brake release piston (61) comprises a primary brake release piston (61a) associated with a primary brake release chamber (62a), and a secondary brake release piston (61b) associated with a secondary brake release chamber (62b), said primary and secondary chambers (62a, 62b) extending radially around the shaft (2) in such a manner that projections of the primary brake release chamber (62a) and of the secondary brake release chamber (62b) onto a plane perpendicular to a longitudinal axis (X-X) defined by the axis of rotation of the hydraulic machine (1) are superposed, at least in part.

A hydraulic pump assembly comprises a rotatable piston drum (20) with at least one centrifugal lever (23) pivotally attached thereto for radial movements between radial flanges (20) under the action of centrifugal force at rotation of the piston drum. The centrifugal lever (23) is arranged to control the position of a valve member, preferably a ball (22), at the opening end of a bore (21) in the piston drum (20). There is a defined friction surface (28; 32) between the lever (23) and one of the radial flanges (20), and there are spring means (29-31; 25, 33) for resiliently biasing the lever against said one of the flanges.

A hydraulic motor assembly includes a flow controller, a displacement controller and a hydraulic motor. The flow controller controls the flow of hydraulic fluid through the hydraulic motor and the displacement controller controls motor displacement. The hydraulic motor converts the pressure and flow into angular displacement of a drive shaft. An electrical generator is connected to the motor drive shaft and provides electrical power to accommodate a varying electrical load. As the electrical load varies, the flow controller and displacement controller vary the flow and displacement of the hydraulic motor to vary the torque applied to the generator by the drive shaft so that the drive shaft rotates at a desired speed.

A radial piston motor includes a cam body and a working member. The cam body includes circumferentially arranged lobes. Each lobe includes a cam section for guiding a piston radially outwards. Each cam section includes a deceleration phase configured to radially decelerate an engaging piston in the case of constant rotational speed and an acceleration phase configured to radially accelerate an engaging piston in the case of constant rotational speed. The working member is rotatable relative to the cam body and has circumferentially arranged pistons. The number of pistons and the number of lobes have the number one as the only common factor and the numbers differ from each other. The deceleration phase is smaller than the acceleration phase.