A manipulator for concrete pumps having an articulated boom with at least two boom arms and a hydraulic drive that pivots one or more of the boom arms. A hydraulic cylinder has piston and rod side working volumes. A hydraulic circuit has a first switching state in which the hydraulic circuit connects a first working port for feed or discharge of hydraulic fluid to the rod-side working volume and connects a second working port for feed or discharge of hydraulic fluid to the piston-side working volume. In a second switching state, the hydraulic circuit separates the first working port from the first fluid channel and thereby connects the first fluid channel to the second fluid channel for the feed of hydraulic fluid from the rod-side to the piston side working volume. A sensor acquires an operating state variable based upon which an activation assembly sets the switching state.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line (4), and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

A counter pressure valve arrangement for controlling a pressure level of a hydraulic fluid in a return line from a hydraulic actuator arrangement. The counter pressure valve arrangement comprises a counter pressure valve having: a moveable valve member; a counter pressure regulating port configured for being connected to the hydraulic actuator arrangement via the return line; a tank port configured for being connected to a tank or low pressure reservoir for storing low pressure hydraulic fluid; and a pump port configured for being connected to a source of pressurised hydraulic fluid. A first position of the valve member effects fluid communication between the pump port and the counter pressure regulating port for supplying pressurised hydraulic fluid to the return line, and a second position of the valve member effects fluid communication between the counter pressure regulating port and the tank port for discharging hydraulic fluid from the return line to the tank.

An actuated valve system includes a valve including a flow controlling valve element, an actuator assembled with the valve and including an inlet port in fluid communication with a fluid driven actuator member operatively connected with the valve element and movable from a normal position to an actuated position in response to pressurization of the inlet port to at least a minimum actuating pressure, a pilot valve operable to supply pressurized fluid to the actuator inlet port in a first position and to exhaust pressurized fluid from the actuator inlet port through an exhaust port in the pilot valve in a second position, and a backpressure arrangement in fluid communication with the actuator inlet port to retain a positive pressure smaller than the minimum actuating pressure against the actuator member when the pilot valve is moved to the second position.

Disclosed are an adjustable load pressure compensation balancing system, an end cover, and a counterbalance valve. The adjustable load pressure compensation balancing system comprises: an adjustable orifice control module and a counterbalance valve control module, wherein the adjustable orifice control module is used for receiving control oil generated when a luffing system descends and oil from a descending cavity of a luffing cylinder; the counterbalance valve control module is used for receiving the control oil generated when the luffing system descends; the pressure applied to the counterbalance valve control module by the control oil is maximum when the luffing system starts to descend, and then decreases gradually; and the pressure applied to the adjustable orifice control module by the oil from the descending cavity is minimum when the luffing system starts to descend, and then increases gradually.

Embodiments of the present invention disclose a valve. The valve includes: a valve casing, a main valve spool and a counterbalance valve spool. The counterbalance valve spool is disposed in a main valve spool internal cavity of the main valve spool and is slidable between a first counterbalance valve spool position and a second counterbalance valve spool position. The counterbalance valve spool includes: a counterbalance valve spool body; and a first counterbalance valve spool recess formed on an outer periphery of the counterbalance valve spool body. In a state where the counterbalance valve spool is in the first counterbalance valve spool position, an inlet of an outlet passage of the main valve spool is closed by the counterbalance valve spool; and in a state where the counterbalance valve spool is in the second counterbalance valve spool position, the inlet of the outlet passage of the main valve spool is opened by the counterbalance valve spool through the first counterbalance valve spool recess of the counterbalance valve spool, so that a second working port is in communication with a return port through an inlet passage configured for the second working port, the first counterbalance valve spool recess and the outlet passage.

A hydraulic circuit is disclosed. The hydraulic circuit may comprise an actuation valve configured to actuate a flow of hydraulic fluid to and from the hydraulic consumer, a first control valve in fluid communication with the actuation valve through a first pilot line and configured to displace the actuation valve to a first position when actuated, and a second control valve in fluid communication with the actuation valve through a second pilot line and configured to displace the actuation valve to a second position when actuated. The first pilot line and the second line may each have a fixed minimum back pressure sufficient to maintain dissolved air in the hydraulic fluid.

A return manifold includes a housing having a first workport, a second workport, a third workport, and a fourth workport, and defining a first chamber and a second chamber. The return manifold includes a back-pressure disk arranged between the first workport and the first chamber, a bypass disk arranged between the first chamber and the second chamber, a back-pressure spring biased between the back-pressure disk and the bypass disk, and a bypass spring biased against the bypass disk. The back-pressure disk and the bypass disk are hydro-mechanically coupled so that movement of the bypass disk alters a force on the back-pressure disk and movement of the back-pressure disk alters a force on the bypass disk.

A sub-system 200 for an aircraft hydraulic system 20 that includes a first inlet 202 for receiving fluid from a supply 22 of hydraulic fluid, a system valve 210 for controlling fluid flow from the sub-system 200 to a hydraulically-operable system 24 of the aircraft hydraulic system 20, a check valve 220 for permitting fluid flow from the sub-system 200 and preventing or hindering fluid flow into the sub-system 200, a second inlet 240 for receiving fluid from a second supply 28 of hydraulic fluid, and a selector 230. The selector 230 configured to place the system valve 210 in fluid communication with the first inlet 202 when the selector 230 is in a first state, and to place the system valve 210 in fluid communication with the check valve 220 and the second inlet 240 when the selector 230 is in a second state different from the first state.

In an exemplary method of monitoring performance of a fluid driven actuator for a valve, pressurized fluid is supplied through an actuator supply line to an inlet port of the actuator during a first time period to operate the actuator. Changes corresponding to a fluid flow condition in the actuator supply line are measured during the first time period, and the measured changes are analyzed to identify a non-compliant condition in at least one of the valve and the actuator. An output communicating the identified non-compliant condition is then generated.