A hydraulic machine is provided. A first flow control valve directs fluid from a first fluid supply to a first actuator when the first flow control valve is in a first position. A conflux control valve directs fluid from the first fluid supply to a second flow control valve when the conflux control valve is in a conflux position. The second flow control valve directs fluid from a second fluid supply and the first fluid supply to a second actuator when second flow control valve is in a second position. A bypass path allows the first fluid supply to communicate with the conflux control valve by passing around the first flow control valve.

Flow control over a hydraulic pump and flow dividing control of a plurality of directional control valves associated with actuators can stably be exercised even in a case in which differential pressures across the directional control valves are quite low, an abrupt change in a flow rate of the hydraulic fluid supplied to each actuator is prevented and excellent combined operability is realized even in an abrupt change in a demanded flow rate at a time of transition from a combined operation to a sole operation, and realizing excellent combined operability, and a meter-in loss in each directional control valve is reduced to realize high energy efficiency. Demanded flow rates of the directional control valves are calculated from input amounts of operation levers, openings of flow control valves are controlled using the demanded flow rates, a meter-in pressure loss of a predetermined directional control valve is calculated from the demanded flow rates and meter-in opening areas of the directional control valves, and a set pressure of an unloading valve is controlled using a value of the meter-in pressure loss.

The present invention relates to a work machine having at least one hydraulic actuator for actuating a piece of working equipment and having a first displacement unit that is driven by a drive assembly of the work machine and that feeds the hydraulic actuator with hydraulic medium from a hydraulic tank, wherein at least one second displacement unit is provided that is driven by the drive assembly and that feeds the hydraulic actuator and/or further hydraulic consumers with hydraulic medium from a hydraulic tank in the working mode and that is drivable during a recovery mode by the hydraulic volume displaced by the at least one hydraulic actuator or by a hydraulic consumer to feed kinetic energy back to the drive assembly.

A fluid supply system supplying multiple fluid consumers of a vehicle with fluid, the fluid supply system including: a first pump supplying a first fluid consumer, arranged in a first supply circulation of the vehicle, with fluid; a second pump supplying a second fluid consumer, arranged in a second supply circulation of the vehicle, with fluid; and a directional control valve adjustable between a first valve position and at least one other, second valve position and preferably includes an electromagnetic device for adjusting. The directional control valve allows the fluid to be delivered from the second pump into the first supply circulation in the first valve position and separates the first supply circulation from the second pump, or allows the fluid to be delivered from the second pump into the first supply circulation only to a restricted extent as compared to the first valve position, in the second valve position.

To provide a work machine that makes it possible to drive actuators faster and more accurately by supplying flows to the actuators accurately at target rates without depending on load variations in a case where the machine body is controlled automatically by command inputs of a controller, while high operability is ensured for manual operation by an operator. In a case where a machine control function is cancelled via a machine control switch, a controller cancels limitation of the flow rate of a hydraulic fluid supplied to a plurality of directional control valves, the limitation being performed by the auxiliary flow rate control devices, and in a case where the machine control function is selected via the machine control switch, the controller causes the auxiliary flow rate control devices to limit the flow rate of the hydraulic fluid supplied to the plurality of directional control valves.

A fluid pressure control device includes a first switching valve provided on a downstream of a first travel control valve in the first main passage and having an open position and a priority position, a second switching valve provided on a downstream of a second travel control valve in the second main passage and having an open position and a priority position, and a merging passage connecting a downstream of the first switching valve and a downstream of the second switching valve. In a state where first work control valves and second work control valves are not operated and the first travel control valve is operated, the first switching valve is at a priority position, and in a state where the first work control valves and the second work control valves are not operated and the second travel control valves is operated, the second switching valve is at a priority position.

A control valve assembly for indirect pneumatic control and method for controlling a working fluid pressure, which enable precise, sensitive and speed-variable controlling. The assembly includes two valve units, a working fluid inlet, and a control fluid inlet. A working fluid channel connects the working fluid inlet through the two valve units to an outlet. A valve piston arranged within a valve cylinder of the valve units is movable between open and closed positions. A spring element biases the valve piston toward the closed position, and a control pressure chamber applies a control pressure counteracting the spring element's bias. When a control pressure is applied in the first chamber, the first valve piston is moved to the open position. Two opposite valve surfaces form a valve opening opened at varying widths when the valve piston is moved in the valve cylinder because of a changing control pressure, and the working pressure can be finely adjusted corresponding to the valve opening width depending on the control pressure.

An example aircraft includes (i) a landing gear having a chassis, an axle, and wheels mounted to ends of the axle; (ii) a hydraulic actuator including a cylinder, a first piston coupled to the chassis, and a second piston coupled to the axle; and (iii) a directional control valve including: inlet ports configured to be fluidly coupled to a source of pressurized fluid, tank ports configured to be fluidly coupled to a tank, and workports configured to be fluidly coupled to the hydraulic actuator.

The present disclosure relates to the technical field of cranes, and in particular to a crane hydraulic control system and a crane. The crane hydraulic control system of the present disclosure includes a prime mover, an execution control mechanism, a hydraulic baking device, a running energy recycling device and an operation energy recycling device. By means of cooperation among the operation energy recycling device, the energy recovery device and the hydraulic energy conversion device, kinetic energy in a driving braking process of the crane and the potential energy in a load lowering process are respectively converted into hydraulic energy for recovery, storage and reuse, therefore, the present disclosure can achieve the recovery of the superstructure energy and the lower vehicle energy of the crane so as to effectively reduce the energy waste.

The invention relates to a method for controlling a hydraulically actuated drive unit (1-3), especially for a valve or control device, wherein at least on a part of the displacement of the drive unit the displacement speed (v) is detected and compared with a predetermined target displacement speed (v), whereupon in the case of a difference between actual value (v) and target value (v) of the speed, the controlling of the drive unit (1-3) is changed such that the displacement speed (v) of the drive unit is adapted to the target value (v).