A downforce control system for an agricultural ground engaging unit provides individual control of each agricultural ground engaging row unit by providing a proportional pressure control valve connected to the retracting chamber of a double acting cylinder which varies the upward force produced by the retracting chamber of the cylinder against a constant counteracting downward force produced by an extending chamber of the cylinder, the valve control based on a comparison of a sensed resultant downward force on the agricultural ground engaging row unit and a predetermined target downward force.

A hydraulic system including a first cylinder conduit configured to couple to a cylinder, an auxiliary conduit configured to couple to a case drain conduit, and a pressure regulator coupled to the first cylinder conduit and to the auxiliary conduit. The pressure regulator may block fluid flow to the auxiliary conduit if a first fluid pressure is less than or equal to a threshold pressure and enable fluid flow if the first fluid pressure is greater than the threshold pressure. The hydraulic system further includes a supplemental conduit with a check valve that directs fluid from the auxiliary conduit to a reservoir. The check valve blocks fluid flow if a second fluid pressure is less than or equal to a third fluid pressure, and enables fluid flow if the second fluid pressure greater than the third fluid pressure.

Disclosed is a multi-layer soft pneumatic actuator, including: a surface layer including driving protrusions formed on one surface; a first chamber layer stacked on the other surface of the surface layer and including a first chamber configured to partially overlap the driving protrusion; a second chamber layer stacked on a layer different from the first chamber layer on the other surface of the surface layer, including a second chamber having a partial region overlapping the driving protrusion and the first chamber; and an air line layer configured to inject air into each of the first chamber and the second chamber.

A system for controlling hydraulic fluid flow within a work vehicle includes a flow control valve fluidly coupled to a fluid supply conduit upstream of a hydraulic actuator such that the flow control valve is configured to control the flow rate of hydraulic fluid to the hydraulic actuator. Furthermore, the system includes a computing system configured to receive an input associated with a selected flow rate of the hydraulic fluid being supplied to the hydraulic actuator. Moreover, the computing system is configured to control an operation of the flow control valve such that flow control valve is at a maximum flow position at which an adjustable orifice defined by the valve has a maximum cross-sectional area. Additionally, the computing system is configured to control an operation of a pump such that the pump supplies the hydraulic fluid to the hydraulic actuator through the adjustable orifice at the selected flow rate.

A three-way valve assembly, including a valve body having a fluid flow path and a valve member movable in the fluid flow path between a supply port and a work port, and between a load sense passage and a pressure relief port. The valve member may move between a first position and a second position for controlling flow and regulating fluid pressure differences sensed in the flow path; and for limiting fluid pressure in the flow path to a predetermined pressure level set by a pilot-operated pressure limiter valve when the valve member is in the second position. The valve member may move between the second position and a third position to open the flow path from the load sense passage to the pressure relief port for relieving fluid pressure in the flow path when the fluid pressure from an over-loaded actuator exceeds the predetermined pressure level set by the pressure limiter valve.

A method of calibrating a solenoid actuated valve includes: providing a brake system including a fluid pressure source: providing a valve having a solenoid, and wherein the valve is in fluid communication with the fluid pressure source; operating the fluid pressure source to provide a constant flow of fluid to the valve; energizing the solenoid of the valve with a constant current such that fluid flows through the valve; measuring the pressure of the fluid flowing at the valve; adjusting the current sent to the solenoid until a predetermined pressure has been obtained; storing a nominal current value of the current required to obtain the predetermined pressure; and calibrating the valve by adding a correction offset factor to the nominal current value for future actuation of the solenoid of the valve.

The construction machine includes: a control valve that switchingly supplies hydraulic fluid from a hydraulic pump to a hydraulic actuator; a control valve drive device that supplies pilot secondary hydraulic fluid to the control valve in accordance with an operation of an operation lever device; a pilot hydraulic pump that supplies pilot primary hydraulic fluid to the control valve drive device; a pressure accumulation device that recovers return hydraulic fluid returned from the hydraulic actuator. The construction machine further includes: a check valve provided in a line between the pilot hydraulic pump and the control valve drive device; a pressure reducing valve that supplied the hydraulic fluid accumulated in the pressure accumulation device; a flow rate reduction device; and a controller that controls the flow rate reduction device in accordance with the pressure in the line between the check valve and the control valve drive device.

A fluid system for a machine that includes a linkage. The fluid system includes an actuator, an accumulator, a pilot circuit, and a pressure reducing valve. The actuator is configured to manipulate the linkage. The accumulator is configured to store a fluid discharged by the actuator under pressure. The pilot circuit is fluidly coupled to the accumulator and is configured to receive the fluid from the accumulator. Further, the pressure reducing valve is positioned between the accumulator and the pilot circuit to regulate the pressure of the fluid delivered to the pilot circuit from the accumulator.

An aircraft assembly having: a first part; a second part, the second part being movably mounted with respect to the first part; an electro-hydraulic actuator coupled between the second part and a first anchor point, the actuator comprising a cylinder defining a bore and a piston and rod assembly slidably mounted within the bore and an active chamber within which an increase in fluid pressure causes the actuator to change during a first phase between first and second extension states to move the second part relative to the first part. The electro-hydraulic actuator further includes a hydraulic fluid supply circuit comprising a piezo-electric pump operable to supply pressurised fluid to the active chamber to change the actuator between first and second extension states.

A load sensing valve maintains a differential pressure at a set pressure by controlling a regulator in accordance with a differential pressure between a discharge pressure of a hydraulic pump and a load pressure of hydraulic actuators. A set pressure control device controls the set pressure. A controller controls the set pressure control device to reduce the set pressure more than when the work implement is being operated, when a predetermined determination condition that includes the work implement not being operated is satisfied.