Control systems and feedback assemblies for hydraulic axial displacement machines, such as pumps and motors. The control systems and feedback assemblies can reduce friction on the charging spools and provide for a more reliable return of the swashplate to a neutral position. Aspects of the control systems and feedback assemblies can be modularized for, e.g., easy maintenance and to reduce the overall size of the system.

A piston pump includes a first biasing mechanism configured to bias a swash plate in accordance with supplied control pressure, a second biasing mechanism configured to bias the swash plate against the first biasing mechanism, and a regulator configured to control the control pressure led to the first biasing mechanism in accordance with discharge pressure of the piston pump, wherein the second biasing mechanism has a pressure chamber to which the discharge pressure is led, and a control piston configured to be biased toward the swash plate by the discharge pressure led to the pressure chamber, and the regulator has a biasing member configured to bias the control piston toward the swash plate, and a control spool configured to be moved in accordance with biasing force of the biasing member, the control spool being configured to adjust fluid pressure.

A hydraulic pressurizing medium supply assembly has an adjustable axial piston machine. An actuating cylinder is controlled by way of a pilot valve. The pilot valve is actuated by a control installation. The control installation, as input variables, has an actual pressure and/or an actual swivel angle of the adjustable axial piston machine. One or a plurality of the input variables are compared with a matching nominal value and a control value is emitted, or in each case a control value is emitted. The controlling of the input variables is part of a first closed-loop control circuit. An underlying second closed-loop control circuit has an input variable which is based on the control variable or the control variables and serves as a nominal variable. A further input variable of the second closed-loop control circuit is an actual delivery-volume adjustment rate of the axial piston machine.

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.

A motor-hydraulic machine unit includes an electric motor, a hydraulic machine, and a connection body that has a planar connection surface which delimits first and second working connections. The first and second working connections are each in fluid exchange connection with the hydraulic machine via an assigned first fluid duct in the connection body. The electric motor and the hydraulic machine have a common axis of rotation which is arranged substantially parallel to the connection surface. The hydraulic machine and the electric motor are arranged on opposite sides of the connection body in the direction of the axis of rotation. The connection body is traversed by a drive aperture in the direction of the axis of rotation. The electric motor and the hydraulic machine are in rotary drive connection in a region of the drive aperture.

The present disclosure relates to an adjusting device for adjusting the swash plate of an axial piston machine comprising an adjusting piston, which is connected to the swash plate of the axial piston machine via an adjusting lever, and a regulator for adjusting the adjusting pressure acting on the adjusting piston in dependence on a control force acting on a control piston of the regulator, wherein the adjusting piston is connected to the control piston via a feedback spring. In accordance with the present disclosure the feedback spring is at least partly received in a pot-shaped recess of the control piston.

A hydraulic rotating machine includes a case, a cylinder block housed in the case and having a plurality of cylinders, a piston reciprocatively inserted into the cylinder; a swash plate configured to reciprocate the piston as the cylinder block rotates, a tilt control piston configured to biase the swash plate and control a tilt angle of the swash plate, and a stopper mounted to the case, the stopper being configured to define a minimum tilt angle of the swash plate. The stopper has a sliding surface for slidably supporting the tilt control piston.

A method is for producing, for a hydraulic machine having an actuator, a setpoint-value trajectory satisfying predefined limitations in order to influence an output variable of the hydraulic machine. A trajectory of unlimited setpoint values is fed to a trajectory planning function, which produces the setpoint-value trajectory from the trajectory of unlimited setpoint values. In the trajectory planning function, the trajectory of unlimited setpoint values is differentiated at least twice in order to obtain a trajectory of unlimited setpoint values that is differentiated n times. In the trajectory planning function, at least one limitation is applied to the differentiated trajectory of unlimited setpoint values in order to obtain a differentiated trajectory of limited setpoint values. The differentiated trajectory of limited setpoint values is fed to a filter integrator chain in order to obtain the setpoint-value trajectory.

A rotatable piston assembly for a reciprocating piston type hydraulic machine includes a rotatable piston configured for a controlled rotation and configured to reciprocate within a cylinder bore of the reciprocating piston type hydraulic machine.

A hydraulic fan drive includes an adjustable variable-displacement pump by which a pressurized fluid can be sucked in and can be delivered via a pump pressure port and which has, for adjustment of the delivery volume, an adjustment device with an actuation chamber, which is delimited by an actuation surface of an adjustment piston and to which a pressurized fluid can be supplied for increasing the delivery volume and from which pressurized fluid can be displaced for reducing the delivery volume. The adjustment device further includes a counter chamber, which is delimited by a counter surface, smaller in cross section in comparison with the actuation surface, of an adjustment piston and can be acted on by pump pressure. The adjustment device also includes an actuation spring, which acts so as to adjust the delivery volume toward an extreme value.