A valve member having a supply pressure and a method of controlling the supply pressure in the valve member includes a valve body having a fluid inlet, a fluid outlet, and a controlled port. The valve member includes a spool moveable within the valve body to fluidly connect at least one of the fluid inlet and the fluid outlet with the controlled port. The spool includes an end in fluid communication with a control pressure port and a pin received within the end of the spool that is moveable relative to the spool. Fluid flow through the control pressure port acts against a cross-sectional area of the pin and an annular area of the spool to modulate the supply pressure through the valve member.

A flow control circuit for an actuator is provided. The actuator includes a first chamber and a second chamber, wherein the first chamber experiences a volume change that is larger than a volume change experienced by the second chamber upon actuation of the actuator. The flow control circuit includes a first port configured to be connected to the first chamber, a second port configured to be connected to the second chamber, and a flow control valve assembly including one or more valves configured to provide a flow of pressurized fluid from a pressurized fluid source to one of the first and second ports along a fluid supply path and further configured to provide a flow of fluid from the other of the first and second ports to a fluid sink along a fluid return path. The flow control circuit further includes a fluid bypass path comprising a bypass valve.

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).

A control device generates an operation signal for controlling a pressure of hydraulic oil on a downstream side of the swing motor in a hydraulic device based on an azimuth direction, a swing speed, and a target stopping azimuth direction of a swing body during braking of a swing motor.

An actuator controller for actuating an actuator which can be operated fluidically, having a feed line for an inflow of the working fluid to an actuator connector and having a discharge line for an outflow of the working fluid to a fluid outlet, wherein the feed line is assigned a feed line valve and the discharge line is assigned a discharge valve, which valves are configured in each case to influence a volumetric fluid flow at the actuator connector, and having a control device for actuation of the feed line valve and the discharge valve. A throughflow sensor is arranged in a line section between the discharge valve and the fluid outlet, which throughflow sensor is configured for determining a volumetric fluid flow in the discharge line and for providing a throughflow signal.

There is provided a hydraulic driving device for working machine having operability handling a change in burden weight in a front working device due to a loaded burden and the like when the working machine that accumulates energy in an accumulator and recovers and regenerates the energy performs an operation of lowering the front working device. A hydraulic driving device 5 includes a main pump 101, a boom cylinder 3, a tank 20, a flow rate control valve 6, an accumulator 300, a first differential pressure control valve 201, and a second differential pressure control valve 202. The first differential pressure control valve 201 is located between the boom cylinder 3 and the accumulator 300. The first differential pressure control valve 201 performs control on discharge oil from the boom cylinder 3 such that a differential pressure between before and after the flow rate control valve 6 becomes a target differential pressure. The second differential pressure control valve 202 is located between the accumulator 300 and the tank 20. The second differential pressure control valve 202 performs control on the discharge oil such that a differential pressure between an upstream pressure and a downstream pressure of the flow rate control valve 6 and the first differential pressure control valve 201 becomes the target differential pressure. The first and the second differential pressure control valves 201 and 202 are configured such that the target differential pressure increases according to an increase in pressure of the discharge oil.

The present invention relates to a control valve, for hydraulic lifters used on tractors, and having a body (10), at least one main inlet line (11) which transfers fluid into the body (10), and a check valve (23) for controlling the passage of fluid, coming from the main inlet line (11), to a cylinder line (14).

A hydraulic excavator drive system includes: first and second pumps; arm cylinder; arm first control valve connected to the cylinder by an arm crowding supply line and arm pushing supply line; arm second control valve connected to the supply lines by a first and second replenishment line; and arm operation device that outputs an operation signal corresponding to an inclination angle of an operating lever. The arm second control valve is configured so, when performing an arm crowding operation, an opening area at a meter-in side changes in accordance with the operation signal, and an opening area at a meter-out side is: kept to zero when a predetermined condition is not satisfied; and kept to zero until the operation signal becomes a setting value or greater, and when the operation signal has become the setting value or greater, increases to a maximum value when the predetermined condition is satisfied.

Apparatuses, systems and methods are provided for controlling one or more fluid actuated devices; e.g., actuators such as hydraulic cylinders. A method is provided, for example, involving actuation fluid, a first actuator and a second actuator. During this method, a quantity of the actuation fluid within the second actuator is pressurized using a quantity of the actuation fluid within the first actuator.

A method for controlling a speed of a hydraulic cylinder (2) in a hydraulic system (1) is provided. The hydraulic system (1) may include a hydraulic cylinder (2) fluidly connected to a load-holding valve arrangement (3) including a first load-holding valve (4) connected to a first end (5) of the hydraulic cylinder (2) and a second load-holding valve (6) connected to a second end (7) of the hydraulic cylinder (2). The hydraulic system (1) may further include a flow-control valve arrangement (8) comprising a directional flow-control valve (9) and at least one hydraulic pump (10).