A hydraulic system for controlling bleed down and retraction of a boom within a safety envelope includes a backup battery power supply, and at least a first boom lift hydraulic cylinder configured to raise and lower the boom. The first boom lift hydraulic cylinder includes a solenoid bleed valve electrically connected to the backup battery power supply. The hydraulic system also includes an input device controllable by an operator of the boom. The input device may, for instance, be used by the operator to initiate bleed down and retraction of the boom from an elevated position. To accommodate independent failsafe features of the system, the input device is configured to selectively actuate the solenoid bleed valve using electrical power supplied from the backup battery power supply.

When hydraulic fluid discharged from a hydraulic actuator is to be recovered for driving a different hydraulic actuator, the recovery frequency is increased to achieve further energy saving. To this end, a pressure increasing circuit 36 is provided in which a communication pressure increasing valve 12 is disposed in a communication passage 26 that connects a bottom side line 23 of and a rod side line 24 a boom cylinder 4. A recovery control valve 11 is controlled such that, when a first operation unit 5 is operated in a boom lowering direction (own weight falling direction of the boom) and a second operation unit 6 is operated simultaneously, only if the pressure at the bottom side of the boom cylinder 4 is higher than the pressure at the arm cylinder side that is a recovery destination of hydraulic fluid, the recovery control valve 11 is opened to recover the flow rate discharged from the bottom side of the boom cylinder 4 to the arm cylinder side.

A hydraulic system, preferably for actuating and engaging a mobile slurry pump, includes a primary circuit, actuating a first hydraulic consumer, which circuit has a hydraulic drive assembly including at least one motor-driven hydraulic pump. The hydraulic system further includes a secondary circuit, actuating a second hydraulic consumer, which circuit has a second hydraulic drive assembly including at least one additional motor-driven hydraulic pump. In a first operating state, hydraulic oil from a common tank can be admitted to the hydraulic consumers arranged in the primary circuit and in the secondary circuit via the hydraulic drive assemblies thereof, independently of one another. In a second operating state, a portion of the hydraulic oil is supplied from the primary circuit to the secondary circuit to actuate the second consumer.

In one aspect, a system for rephasing fluid-driven actuators may include a plurality of fluid-driven actuators fluidly coupled together in series. A controller may be configured to monitor a position differential existing between current positions of rods of the actuators relative to a differential threshold based on sensor measurements. The actuators may be out-of-phase when the monitored differential exceeds the threshold. The controller may also be configured to initiate a flow of fluid to the actuators to rephase the actuators when the monitored differential exceeds the threshold. The controller may further be configured to continue to monitor the differential following initiation of the flow of fluid to the actuators. Additionally, the controller may be configured to implement a control action associated with terminating the rephasing of the actuators when the monitored differential remains constant after a first time period has elapsed following initiation of the flow of fluid.

The present disclosure relates to a backhoe loader energy recovery and reuse system and a control method thereof, and a backhoe loader, wherein the system comprises: an actuator, configured to drive a working device to perform an action with hydraulic oil as a medium, and having a first cavity and a second cavity; a reversing valve, having a first working oil port communicated with the first cavity and a second working oil port communicated with the second cavity, the reversing valve being configured to reverse the actuator; a stabilizing valve group, having a first oil port, a second oil port, a third oil port and a fourth oil port, the first oil port and the second oil port being communicated with the first cavity and the second cavity, respectively, and the third oil port being communicated with an oil tank; and an energy storage part, communicated with the fourth oil port and configured to store hydraulic energy; wherein the first oil port and the third oil port have a first communication state therebetween, in which the hydraulic oil in the first cavity can enter the oil tank; the second oil port and the fourth oil port can be selectively connected or disconnected, and in a connected state, the second cavity is communicated with the energy storage part.

A hydraulic control valve maintains the pressure at a control port at a desired percentage of the pressure at two other ports as the pressure at the two other ports varies. Upon the pressure at the control port reaching a predetermined pressure setting, a fourth port will open to maintain the control port at a second desired percentage of the two other ports.

A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.

The problem of providing a cylinder/piston unit which can be installed in a relatively space-saving manner, in particular, for use in a master/slave arrangement is solved by virtue of the fact that a first, outer hydraulic cylinder (2) is provided, in which a first piston (6) is mounted sealingly with respect to the cylinder inner wall of the first hydraulic cylinder (2) and longitudinally movable in the latter, and the first piston (6) supports a second, inner hydraulic cylinder (3), in which a second piston (9) is mounted sealingly with respect to the cylinder inner wall of the second hydraulic cylinder (3) and longitudinally movable in the latter. The second, inner hydraulic cylinder (3) supports a piston rod (10), and the piston rod (10) is connected at the end thereof which is remote from the second piston (9) to an end (4) of the outer hydraulic cylinder (2).

A device for automatically adjusting the working width of the first plough body of a plough in accordance with the variable working width of subsequent plough bodies. A first hydraulic cylinder displaces a rear frame section laterally. A second hydraulic cylinder pivots the rear frame section to adjust a transverse spacing of the plough bodies. The first hydraulic cylinder includes a multi-stage cylinder. A first cylinder stage forms a main lateral control, and a second cylinder stage forms an automatic working-width control for the first plough body. The second cylinder stage is in hydraulic-fluid communication with the second hydraulic cylinder in a master-slave configuration. The second cylinder stage is master or the slave depending on a moving direction of the cylinder stage and the second hydraulic cylinder being slave or the master. Piston diameters are matched to provide a correction of a lateral displacement of the front frame section.

A control system may be used to control actuators that actuate movement of flight control surfaces of an aircraft. Each actuator is couplable to a flight control surface and includes a motion control assembly having a hydraulic motor and a drive path from the hydraulic motor to the flight control surface. Each hydraulic motor includes an extend port and a retract port. The system includes a hydraulic control module fluidly connected to the extend port and the retract port of each hydraulic motor and a controller operable to output hydraulic power from the hydraulic control module to the motion control assembly to actuate movement of the flight control surfaces. The controller is configured to identify an actuator that positionally leads the other actuators and reduce hydraulic power to the motion control assembly assigned to such actuator.