A directly-controlled hydraulic directional valve includes a housing, control piston, first and second springs, double-stroke solenoid, spring plate, adjustment device, and electronics. The piston is longitudinally displaceable in a bore in the housing, either directly or via a control sleeve. The springs are positioned in a region of an end of the piston remote from the solenoid. One end of each spring is supported on the spring plate, which is clamped between the springs and the piston. The other end of the first spring is fixed to the housing, and the other end of the second spring is fixed to the adjustment device. The first spring exerts a force on the piston in a first direction, and the second spring exerts a force on the piston in a second opposite direction, so as to bias the piston into a preferred position. The solenoid is mounted on a side of the housing, and is operable to move the piston out from the preferred position in opposite directions proportional to an electric current from the electronics, such that the piston moves to the preferred position in response to each of non-actuation of the solenoid and a fault in the electronics. The adjustment device is operable to alter a position of the other end of the second spring to adjust the preferred position of the piston.

The device includes a main valve, first and second auxiliary valves, a valve body and a filter. The main, which has first and second auxiliary valves are mounted on the valve body, which has an air inlet, a cylinder port and an air discharging port. The air inlet is in communication with the main valve through a first air passage, the cylinder port is sequentially in communication with the first and second auxiliary valves, and the main valve through a second air passage. The air discharging port is sequentially in communication with the first and second auxiliary valves and the main valve through a third air passage. The main and the second auxiliary valves are solenoid valves, and the first auxiliary valve is a hand-operated valve. An air outlet of the filter is in communication with the air inlet. The filter is used for filtering out impurities in gas.

A stepper motor driven actuator system is provided. The system includes a stepper motor, a cam, and a gearbox system. The gearbox system operatively connects the stepper motor to the cam. The cam rotates in response to stepping of the stepper motor. The system also includes a valve having a control piston located therein. The control piston is configured to translate in response to rotation of the cam. The system further includes a rotary actuator. The rotary actuator is fluidly connected to the valve, and the rotary actuator is configured to rotate the cam in response to translation of the control piston.

A valve device that changes the direction of flow of a hydraulic fluid supplied to and discharged from a cylinder mechanism to actuate the cylinder mechanism, the valve device including: a control valve including a main spool axially movable between different positions; a lock valve including a plunger and a pressure chamber; and a selector valve including a selector spool operable in conjunction with the main spool to axially move between different positions, the selector spool being located adjacent to the main spool and having an axis crossing an axis of the main spool.

A stepper motor driven actuator system is provided. The system includes a stepper motor, a cam, and a gearbox system. The gearbox system operatively connects the stepper motor to the cam. The cam rotates in response to stepping of the stepper motor. The system also includes a valve having a control piston located therein. The control piston is configured to translate in response to rotation of the cam. The system further includes a rotary actuator. The rotary actuator is fluidly connected to the valve, and the rotary actuator is configured to rotate the cam in response to translation of the control piston.

A solenoid device including pressure altering means for altering an output pressure of the solenoid device; and an actuator for providing an actuating signal to said pressure altering means; wherein the solenoid device further includes a sensor arranged to sense a control value of the solenoid device, and a controller which receives a request and is arranged to control delivery of power to the actuator with feedback from the sensor until the control value meets the request.

In a valve device, travel control valve unit has a communication path causing the lead-out passages of the left and right travel control valve units to communicate with each other, and a spool has a lead-out side land portion configured to cause communication or shut-off of the communication between the lead-out passage and the communication path, a discharge-side land portion configured to cause communication or shut-off of the communication between the actuator passage and the discharge passage, a discharge portion configured to discharge a part of the working fluid led from the supply passage to the lead-out passage to the discharge passage at a movement initial stage of the spool, and a communication portion configured to cause the lead-out passage and the communication path to communicate with each other at a movement final stage of the spool.

A spool valve arrangement comprising a spool arranged for linear movement within a bore to regulate flow of fluid through the bore according to the linear position of the spool relative to the bore, the spool having an end arranged to be engaged, in use, by a drive member to cause the linear movement, the spool valve arrangement further comprising a sliding block component moveably attached to the spool end and arranged to engage with the drive member, in use, such that the drive member engages with the spool end via the sliding block component and the sliding block component moves relative to the spool to compensate for non-linear movement of the drive member.

Hydraulic systems and associated methods configured to reduce leakage past a spool valve when the system is in a neutral state. Leakage reduction is achieved by shifting the spool valve within the spool bore. The shifting direction can depend on whether the system has a relatively high load or a relatively low load in the neutral state. The amount of shifting can depend on the pressure differential between the supply line and the work port, and/or the pressure differential between the work port and the tank line.

A control valve including: a valve housing including a piston space; and a control piston which is movably arranged in the piston space and sub-divides the piston space into at least a first valve space and a second valve space, the control valve including at least a leakage path which sets a desired leakage between the first valve space and the second valve space. A motor vehicle device including an adjustable rotary pump including an adjusting means, for adjusting a delivery volume of the rotary pump, and the control valve, using which a pressure for adjusting the adjusting means can be governed, the motor vehicle device including a means which presses the control piston into a first position and holds it there, and the at least one other inlet of the control valve is connected to a high-pressure side of the rotary pump when the rotary pump is in operation.