An example valve includes a valve piston configured to block fluid flow from a first port of the valve to a second port of the valve when the valve is in a closed position; a forward flow spring applying a first biasing force on the valve piston in a distal direction; a reverse flow spring applying a second biasing force on the valve piston in a proximal direction; and a pressure setting spring applying a third biasing force on a check element in the distal direction, wherein fluid from the first port applies a fluid force on the check element in the proximal direction, and fluid from a pilot port applies a respective fluid force on the check element in the distal direction.

An example valve includes a valve piston configured to block fluid flow from a first port of the valve to a second port of the valve when the valve is in a closed position; a forward flow spring applying a first biasing force on the valve piston in a distal direction; a reverse flow spring applying a second biasing force on the valve piston in a proximal direction; and a pressure setting spring applying a third biasing force on a check element in the distal direction, wherein fluid from the first port applies a fluid force on the check element in the proximal direction, and fluid from a pilot port applies a respective fluid force on the check element in the distal direction.

Provided is a hydraulic drive system for a work machine configured with a single solenoid proportional valve for a regeneration circuit, wherein substantially the same actuator speed can be secured irrespective of whether or not hydraulic fluid discharged from a hydraulic actuator is regenerated for driving of another hydraulic actuator. The hydraulic drive system includes: a regeneration line that connects a bottom-side hydraulic chamber of a hydraulic cylinder 4 to a portion between a hydraulic pump device 50 and a second hydraulic actuator 8, and a regeneration flow rate adjustment device that supplies, at an adjusted flow rate, at least part of the discharged hydraulic fluid to a portion between the hydraulic pump device 50 and the second hydraulic actuator; a discharge flow rate adjustment device that discharges, at an adjusted flow rate, the discharged hydraulic fluid to a tank; one electric drive device 22 that simultaneously controls the regeneration flow rate adjustment device and the discharge flow rate adjustment device; and a control unit 27 that outputs a control command to the electric drive device in such a manner that falling speed of a first driven body does not vary significantly, irrespective of the magnitude of the regeneration flow rate caused by the regeneration flow rate adjustment device.

A hydraulically actuatable jib for a loading crane includes at least two jib extensions, the first jib extension being designed as an outer jib extension and the second jib extension being designed as an inner jib extension. At least two feed cylinders extend and react the at least two jib extensions. A hydraulic circuit for a working fluid includes a retraction line for retracting the feed cylinders in a pressurized manner, and the retraction line opens into the feed cylinder of the outer jib extension. A tank is provided for releasing the working fluid, and a control valve can be switched into an open position when the outer jib extension reaches a defined retraction position, particularly when the outer jib extension is substantially fully retracted. The valve thereby supplies the feed cylinder of the inner jib extension with pressurized working fluid.

A hydraulically actuatable jib for a loading crane includes at least two jib extensions, the first jib extension being designed as an outer jib extension and the second jib extension being designed as an inner jib extension. At least two feed cylinders extend and react the at least two jib extensions. A hydraulic circuit for a working fluid includes a retraction line for retracting the feed cylinders in a pressurized manner, and the retraction line opens into the feed cylinder of the outer jib extension. A tank is provided for releasing the working fluid, and a control valve can be switched into an open position when the outer jib extension reaches a defined retraction position, particularly when the outer jib extension is substantially fully retracted. The valve thereby supplies the feed cylinder of the inner jib extension with pressurized working fluid.

A hydraulic valve with a hydraulic fluid, in particular for shifting an actuation piston in a connecting rod for a variable compression internal combustion engine, the hydraulic valve including a valve housing which includes a first operating connection and a second operating connection and a supply connection that is loadable with a hydraulic pressure of the hydraulic fluid so that a piston that is movably arranged in the valve housing is displaceable against a force of a preloaded spring, wherein the piston is optionally arrestable in a first shifting position or in a second shifting position, wherein an axial shaft arranged in the valve housing includes a shifting coulisse, and wherein the piston is movable from the first shifting position into the second shifting position and from the second shifting position into the first shifting position by a control element guided in the shifting coulisse.

The invention relates to a hydraulic positioning device for an agricultural implement, wherein preferably a uniform movement of several hydraulic cylinders is achieved by using a progressive distributor.

The invention relates to a hydraulic positioning device for an agricultural implement, wherein preferably a uniform movement of several hydraulic cylinders is achieved by using a progressive distributor.

A valve structure (1) for driving reversible ploughs (40), comprising a first port (3) adapted to be in fluid communication with a pump (P) in a first configuration of the plough (40) and adapted to be in fluid communication with a tank (T) in a second reversed configuration of the plough (40), and a second port (4) adapted to be in fluid communication with the tank (T) in the first configuration of the plough (40) and adapted to be in fluid communication with the pump (P) in the second reversed configuration of the plough (40), a body (2) which includes a first seat (5) and a second seat (6), the seats housing respective moving spools (13, 14), a first interconnection port (7a) for the connection of the valve structure (1) to a first chamber (10a) of a first hydraulic cylinder (10) for longitudinally aligning the plough (40), and a second interconnection port (7b) for the connection to a second chamber (10b) of the first hydraulic cylinder (10), a third interconnection port (8a) for the connection of the valve structure (1) to a first chamber (12a) of a second hydraulic cylinder (12) for reversing the plough (40), and a fourth interconnection port (8b) for the connection to a second chamber (12b) of the second hydraulic cylinder (12). The valve structure (1) comprises hydraulic components configured to control the relative displacement of the spools (13, 14) to automatically control the movement of the cylinders (10, 12). A check valve (31) enables the fluid to flow in the second reversed configuration of the plough (40).

A downhole tractor has at least one hydraulic drive section, comprising a first hydraulic supply line for actuating at least one hydraulic cylinder for actuating at least one tractor arm and a second hydraulic supply line for driving at least one hydraulic motor for rotating at least one tractor wheel. The downhole tractor further comprises a hydraulic power pack configured for supplying hydraulic fluid to the hydraulic supply lines. The hydraulic power pack comprises a pressure-setting valve provided in between the first hydraulic supply line and the second hydraulic supply line, wherein the pressure-setting valve is configured for feeding excess hydraulic fluid in the first hydraulic supply line to the second hydraulic supply line to increase the speed of the downhole tractor.