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.

The present invention discloses a load-sensing multi-way valve with a variable differential pressure, where each valve group uses a new element: an electro-hydraulic pressure compensation valve, so as to implement continuous real-time adjustment and control of compensated differential pressure and real-time position feedback and monitoring of a compensation valve trim, and overcome a flow mismatch problem of a conventional LS system in a flow saturation working condition and problems of a fixed shunting proportion of an LUDV system and poor operation coordination of actuators. The load-sensing multi-way valve with a variable differential pressure disclosed in the present invention has advantages such as strong working condition applicability, high flow distribution accuracy, and strong technicality.

Disclosed embodiments include hydraulic systems which provide power to lift, tilt and auxiliary (e.g., implement) functions, including high-flow auxiliary functions, with increased efficiency. Disclosed embodiments incorporate a single variable displacement pump that supplies pressurized fluid to a main control valve (e.g., for lift, tilt, and auxiliary functions) and a bypass circuit. The main control valve supplies fluid to control lift, tilt, and auxiliary flow for implements. The bypass circuit combines flow with the output of the auxiliary section of the main control valve to optionally provide high-flow for selected implements. The single variable displacement pump can then be set to different output flow levels, with the bypass circuit functioning differently under different conditions to optimize hydraulic flow to carryout various tasks under various conditions.

The aerial work platform includes a chassis, a basket, a hydraulic lifting structure and a hydraulic system. A control unit includes a circulation circuit, an electric motor pump and a flow regulator. To simultaneous displace two different parts of the lifting structure, the actuators are divided between first and second groups and the control unit determines first and second target flow rates, while controlling the motor pump with a delivery flow rate greater than or equal to the sum of the target flow rates. The control unit controls the flow rate controller to send toward the groups a regulated proportion of the fluid from the motor pump, presenting a flow rate equal to the sum of the target flow rates, and then to divide this regulated proportion into two adjusted parts, respectively presenting the first and second target flow rates and respectively sent to the first and second groups.

The present disclosure relates to a hydraulic control circuit for crane slewing gear having directional valves arranged in work lines and controllable separately for the inflow and outflow to the hydraulic motor for the carrying out of a rotational movement of the slewing gear, wherein an inflow valve serves the control of the oil inflow from a hydraulic pump via the work line to the hydraulic motor and an outflow valve is provided via which the hydraulic motor can be relieved to the tank, wherein the work lines are each connected via at least one check valve to a common inlet of the outflow valve to relieve the hydraulic motor independently of the direction of rotation of the slewing gear via an outflow valve into the tank.

To keep operability of a hydraulic actuator excellent even in a state pressure has been sufficiently accumulated in a pressure accumulator. In a hydraulic driving device of a work machine including a hydraulic actuator, a tank, a flow control valve, and a pressure accumulator, there are further provided with a first pressure compensation valve that is for controlling difference between front and back pressures of the flow control valve constant and a second pressure compensation valve that is arranged between the pressure accumulator and the tank and is for controlling difference between front and back pressures of the flow control valve and the first pressure compensation valve constant.

A back-pressure control valve includes: a switching valve configured to open and close the connecting passage; and an emergency operation valve provided in the branch passage, the emergency operation valve being configured to open and close the branch passage by being operated manually. The emergency operation valve has a valve main body and a valve body. The valve body includes: the main body portion having the screw portion threaded into the valve main body; and the seat portion formed on the tip end of the main body portion, the seat portion being configured to open and close the branch passage by being seated on and separated from the valve seat provided in the accommodating hole.

To keep operability of a hydraulic actuator excellent even in a state pressure has been sufficiently accumulated in a pressure accumulator. In a hydraulic driving device of a work machine including a hydraulic actuator, a tank, a flow control valve, and a pressure accumulator, there are further provided with a first pressure compensation valve that is for controlling difference between front and back pressures of the flow control valve constant and a second pressure compensation valve that is arranged between the pressure accumulator and the tank and is for controlling difference between front and back pressures of the flow control valve and the first pressure compensation valve constant.

A hydraulic load-sensing control arrangement for a first and second hydraulic consumer has a variable displacement pump having load-sensing regulation, to which the highest respective load-sensing pressure of consumers is reported. The first consumer has the highest load pressure in normal operation and therefore the highest load-sensing pressure dependent on the load pressure. A pressure reducing valve is arranged in the pressure medium flow path between the variable displacement pump and the first consumer. A spring force from a regulating spring and a regulating pressure dependent on the load pressure of the first consumer are applied in the opening direction of a valve gate in this pressure reducing valve and pressure is applied directly downstream from the pressure reducing valve in the closing direction thereof. A pressure equivalent of the spring force of the regulating spring and the regulating pressure are greater than a pressure of the variable displacement pump.

A load-controlled hydraulic supply for an attachment attached to an agricultural tractor includes a hydraulic high-pressure source providing a volume flow in a supply line, a pressure-compensated control valve including an actuation device for adjusting the volume flow in the supply line, a return line leading to a hydraulic reservoir, and a load-indicating line. The volume flow is adjusted based on pressure feedback prevailing at the load-indicating line.