An object of the present invention is to provide a work machine that makes it possible to perform, with a simple configuration, speed control of respective actuators and thrust control of a particular actuator that regenerates the flow of a return fluid, at the time of combined operation to simultaneously drive the particular actuator and another actuator. For this purpose, a controller calculates a target thrust that is a target value of a thrust of the particular actuator on the basis of an input amount of an operation device and an output value of a posture sensor, calculates a target meter-out pressure that is a target value of a meter-out pressure of the particular actuator on the basis of the target thrust and a meter-in pressure of the particular actuator, and calculates a regeneration control valve target opening area that is a target value of an opening area of a regeneration control valve on the basis of the target meter-out pressure and the meter-out pressure of the particular actuator.

A hydraulic boom control system for a forestry machine includes a pump for pressurizing a hydraulic fluid on a high pressure side, a reservoir for storing hydraulic fluid on a low pressure side, and a first hydraulic cylinder including a cap end and a rod end. The first hydraulic cylinder is configured to actuate the hoist of the boom. A second hydraulic cylinder includes a cap end and a rod end and is configured to actuate the stick of the boom. A first control valve is operable to control the first hydraulic cylinder. A second control valve is operable to control the second hydraulic cylinder. A variable return metering valve is fluidly connected to at least one of the first or second control valves. The variable return metering valve is operable to modulate shared hydraulic fluid flow between the first hydraulic cylinder and the second hydraulic cylinder.

A valve device includes a valve body, a drain chamber wall configured to define a drain chamber, a drain port formed in the drain chamber wall facing the valving element, and a drain passage configured to guide drain fluid from another valve device to the drain chamber, wherein at least one of the drain chamber wall and the valving element includes a communicating passage configured to allow the drain port to communicate with the drain chamber when the movement of the valving element is restricted by the drain chamber wall.

A pivot joint for a robot, including a double-acting pneumatic pivot actuator, which has a first working chamber with a first working port and a second working chamber with a second working port, and further including a valve arrangement having a first valve group for a selective connection of the first working port to one of a pressurization port and an exhaust port, and having a second valve group for a selective connection of the second working port to one of the pressurization port and the exhaust port. The valve arrangement includes a safety valve which is connected to the first working port and to the second working port and which is configured for blocking a connection between the first working port and the second working port in a blocking position and for releasing the connection between the first working port and the second working port in a release position.

Provided is a work machine including a flow control valve serving as a flow control mechanism that controls a flow rate of pressurized fluid from a hydraulic pump to a hydraulic actuator via a first control valve. A controller of the work machine, when the pressurized fluid is supplied to the hydraulic actuator from only an accumulator, drives a second control valve such that a meter-in side of the hydraulic actuator and the accumulator are connected to each other, drives the first control valve such that a meter-out side of the hydraulic actuator and a tank are connected to each other, and drives the flow rate control mechanism such that a flow of the pressurized fluid from the hydraulic pump to the hydraulic actuator via the first control valve is interrupted.

A fluid pressure control device includes a first circuit system having a first pump and a first control valve. The first circuit system includes an intermediate cut valve provided downstream of the first control valve in a first intermediate passage and which connects and disconnects a connection between the first intermediate passage and the tank, and an external output port communicating at a part downstream of the first control valve in the first intermediate passage and upstream of the intermediate cut valve, the external output port being capable of externally supplying working fluid discharged from the first pump.

A hydraulic circuit for a construction machine including a direction control valve group including direction control valves provided in tandem to a center bypass passage, a bleed-off valve provided to the center bypass passage downstream of the direction control valve group, and a control valve controlling an amount of pressure oil to be supplied to the direction control valve.

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 flow rate control apparatus for construction equipment includes: a boom cylinder driven by hydraulic fluid; a first control valve for controlling a hydraulic fluid flow supplied to the boom cylinder; an option actuator driven by hydraulic fluid; a second control valve for controlling a hydraulic fluid flow supplied to the option actuator; a boom cylinder manipulation lever and an option actuator manipulation lever; a confluence line selectively confluence the hydraulic fluid supplied to the boom cylinder with the hydraulic fluid of the option actuator; a center bypass switching valve provided at the furthest downstream side of a fluid supply path of the first hydraulic pump; a confluence switching valve selectively opening and closing the confluence line; a confluence selection valve applying a pilot pressure to the confluence switching valve; and a controller for controlling the confluence selection valve.

A flow control manifold that routes pressurized fluid from one of a first fluid manifold connection and a second fluid manifold connection of the flow control manifold to an input of a work tool and directs return fluid from an outlet of the work tool to the other of the first and second fluid manifold connections not receiving pressurized fluid.