Modular directional valve with two or more crossing elements (E1 . . . En) able, acting only on the entry side, to manage a variable displacement pump (PA) of the load sensing type.

In particular, this management allows in a single drive, unlike the conventional crossing distributors, to make the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads.

A compensated flow rate regulator is placed in the entry side so as to act only on the bypass line LC upstream of the first element (E1 . . . En) while a proportional choke is placed on the load line consisting of a 2-way 2-position tray.

Modular directional valve with two or more crossing elements (E1 . . . En) fed by a variable displacement (PA), negative control or load sensing pump.

A pressure regulator (5) is placed in the entry side and only on the bypass line and upstream of the first element (E1 . . . En).

In the single drive, it makes the flow rate to the utility independent of the load and allows setting a maximum flow rate at the end of the stroke; in multiple drives, it ensures that the sum of the required flow rates is independent of the loads.

A recycling passage 71 is configured to perform pressure oil recycling, in which the recycling passage 71 feeds boom discharge oil 35Fo (recycling discharge oil) discharged from a boom cylinder 23F (a recycling actuator), to the boom cylinder 23F (an actuator actuated with feeding of discharge oil from a second pump 12). A first sensing pressure rising passage 81 feeds a part of boom discharge oil 35Fo to a first unload passage 31 upstream of a first pressure sensing point 61p when the pressure oil recycling is performed.

A pneumatic device having a pneumatic cylinder and a piston movably mounted in the pneumatic cylinder to divide an interior of the pneumatic cylinder into two chambers. The chambers are connected to a line network having a valve assembly. The line network, in a plurality of operating states of the valve assembly serving for venting the respective chamber, connects the respective chamber to at least a respective selected one of a plurality of outflow openings, of the pneumatic device, and in a further operating state of the valve assembly, disconnects the respective chamber from the outflow opening. A control installation of the pneumatic device adjusts the operating state of the valve assembly. The line network is designed so that, in at least three of the operating states for venting the respective chamber, the connection between the respective chamber and the outflow opening is established by mutually dissimilar flow resistances.

An actuator unit includes a rod side chamber and a piston side chamber defined by a piston; a tank; a first opening/closing valve communicating the rod side chamber with the piston side chamber; a second opening/closing valve communicating the piston side chamber with the tank; an suction passage allowing a working fluid to flow from the tank toward the piston side chamber; a rectifying passage allowing the working fluid to flow from the piston side chamber toward the rod side chamber; a pump supplying the working fluid to the rod side chamber; a first discharge passage and a second discharge passage respectively communicating the rod side chamber to the tank; a first passive valve provided on the first discharge passage; a second passive valve provided on the second discharge passage; and a third passive valve configured to communicate and block the first discharge passage.

An object to reduce a relief amount at the start of turning. A hydraulic drive system of a construction machine includes: a turning control valve disposed on a first circulation line extending from a first pump; a boom control valve disposed on a second circulation line extending from a second pump; first and second regulators, which change tilting angles of the first and second pumps; and a controller, which controls one or more solenoid proportional valves, which output a secondary pressure to the first and second regulators. While a turning operation is being performed, if a discharge pressure of the first pump is higher than a first setting value and a discharge pressure of the second pump is lower than a second setting value, the controller lowers first and second horsepower control lines that restrict discharge flow rates of the first and second pumps.

A pneumatic manifold with internal and external porting is machined in a specific sequence for pressurized and exhausting air control. Electro-pneumatic valves and or blocking plates are fastened and sealed to the positions of exterior porting. The electro-pneumatic valves complete the pneumatic circuit already machined in the manifold. Electro-pneumatic valves can be added or removed depending on the required functions. Other exterior ports on the manifold allow for but are not limited to connection of a pressure transducer, exterior pilot feeds, individual open/close speed controls, individual secondary slow down speed controls for open and close. The manifold allows the mounting of three electro-pneumatic valves wherein each valve controls a certain specific sequential function. When used with a compatible means of electronic control, the manifold can replace most pneumatic control devices driving a pneumatic actuator for the purpose of moving an access mechanism, such as a garage door.

Multi-rotor hydraulic drone (1) comprising: a plurality of hydraulic motors (6) each receiving a pressurised fluid, propellers (5) driven by the hydraulic motors (6), at least one hydraulic pump (10) driven by at least one motor (11) for pressurising the fluid, a system for supplying the hydraulic motors (6) with pressurised fluid, a flight controller (14) for controlling the supply system according to the desired rotation speed for the hydraulic motors (6), the supply system comprising several channels (35; 36; 37; 38) for adjusting the power of at least one portion of the hydraulic motors (6).

A work machine includes: a main circuit that supplies a working fluid from a pump to an actuator; a pilot circuit that introduces part of the working fluid from the pump, to a pilot pressure receiving section of a control valve; a bleed-off passage that connects the pump and a tank. The pilot circuit is provided with: a first pressure reducing valve that generates a pilot primary pressure; and second and third pressure reducing valves that generate a pilot secondary pressure to be applied to the control valve and a bleed-off valve. A moving area of a spool of the bleed-off valve has a first moving area where an opening area of a restrictor changes stepwise, and a second moving area where the opening area of the restrictor changes continuously. A controller controls the third pressure reducing valve such that the spool is positioned in the first moving area at the time of non-operation of the actuator, and the spool is positioned in the second moving area at the time of operation of the actuator. The restrictor of the bleed-off valve has a restricting hole that gives a resistance to the working fluid passing therethrough in a case the spool is positioned in the first moving area.

Pump-controlled hydraulic circuits are more efficient than valve-controlled circuits, as they eliminate the energy losses due to flow throttling in valves and require less cooling effort. Presently existing pump-controlled solutions for single rod cylinders encounter an undesirable performance during certain operating conditions. Novel circuit designs employ use of different charge pressures on a pair of pilot-operated charging-control valves or different piston areas and/or spring constants on a shuttle-type charging control valve to shift a critical loading region in a load-force/actuator-velocity plane to a lower load force range, thereby reducing the undesired oscillations experienced in the response of the typical critical loading region. One or more specialized valves are controlled by fluid pressures to provide throttling in the circuit only within the critical loading region, thereby reducing the oscillatory amplitude while avoiding throttling-based energy losses outside the critical region over the majority of the circuit's operational overall operating area.