An electrohydraulic valve system for controlling a braking system of a work machine includes a valve body forming a bore and a fluid channel, a valve spool disposed within the bore, and a first armature positioned with respect to the valve spool to move the valve spool axially within the bore between a first position and a second position. A spring is disposed within the bore, where the valve spool is biased to its first position by the spring. A first electromagnetic coil is operably controlled between an energized state and a de-energized state, and a lockout system is formed at least partially within the valve body. The lockout system includes a second armature, a second electromagnetic coil, and a lockout spring, where the second electromagnetic coil is operably controlled between an energized state and a de-energized independently of the first electromagnetic coil.

A multi-control valve unit includes a housing with built-in spools that are parallel to each other. The housing includes pilot chambers formed therein, the pilot chambers corresponding to both ends of the spools. Solenoid proportional valves are mounted to the housing, such that the solenoid proportional valves are connected to the respective pilot chambers. A hydraulic pressure generator is mounted to the housing, such that the hydraulic pressure generator is connected to the solenoid proportional valves. The hydraulic pressure generator includes an electric motor and a pump.

A servo valve comprising: a fluid transfer valve assembly comprising a supply port and a control port (P.sub.A, P.sub.B); a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal; and a drive means configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow; wherein the drive means comprises a piezo actuator element mounted within and axially movable with the valve spool, the piezo actuator configured to extend axially in response to the control signal to cause corresponding axially movement of the spool.

A valve, having a valve housing, in which a housing interior is formed, in which a movable valve slide is located. The valve slide is impinged upon by a compression spring that is supported via a supporting element on the valve housing. The supporting element has a supporting wall, from which a plurality of supporting arms protrudes, which axially overlap the valve slide in each axial position. On the supporting arms guide surfaces are formed for linear guidance of the valve slide. The supporting arms are springily deflectable and in each case have a radial support surface, with which they are supported on the valve housing.

A valve (V, V1, V2) includes a housing (VG) and a piston (VK) displaceably guided therein. A first end (VK1) of the piston (VK) can be acted upon by a force, with the aid of which the piston (VK) is displaceable against a spring (F) acting upon a second end (VK2) of the piston (VK). The valve (V, V1, V2) has four switching conditions, in which four ports (A, B, P, T) in the housing (VG) are selectively connectable to one another or blocked with respect to one another. In a first switching condition, none of the ports (A, B, P, T) are connected to one another. The spring (F) is configured in such that, in the absence of an application of force onto the first end (VK1), the piston (VK) is held in a position, which corresponds to the first switching condition of the valve (V, V1, V2).

A main flow path that introduces high-pressure air to an air cylinder, or discharges exhaust air therefrom, includes a sub flow path provided alongside the main flow path; an exhaust flow rate adjustment unit that suppresses the operation speed of the air cylinder by adjusting the flow rate of the exhaust air flowing through the sub flow path; and a switching valve that is connected between the air cylinder, the main flow path and the sub flow path, and that connects the main flow path and the sub flow path to the air cylinder in a switching manner. The switching valve is constituted by a spool valve.

A series train of symmetrical dual rod-end double-action hydraulic cylinders with a cross sectional area in a series of powers of 2. The cylinders have corresponding computer controlled valves. The cylinders are switchable into three states. One state of shortcutting 2 fluid ports, another state of driving towards each opposite direction of reciprocation and the third state of idling. In the cylinder train all same polarity ports of the valve assembly are connected by hoses or pipes to align towards the same orientation to enable synchronous reciprocal motion and train power output.

A dynamic load damping apparatus is employed in a hydraulic steering system control circuit of an aircraft. The dynamic load damping apparatus is positioned in the hydraulic steering system control circuit in parallel with a control valve of the control circuit that functions as the hydraulic fluid source of the control circuit and an actuator that controls movements of a nose gear of the aircraft. The dynamic load damping apparatus dampens loads transmitted to the hydraulic actuator that controls the steering movements of the nose gear on the aircraft.

A servo valve comprises a first spool extending along a first spool axis, a second spool extending along a second spool axis, a first piezoelectric actuator, and a second piezoelectric actuator. The first piezoelectric actuator is operatively connected to the first spool for translating the first spool in response to a voltage applied thereto. The second piezoelectric actuator is operatively connected to the second spool for translating the second spool in response to a voltage applied thereto.

A spool valve including a spool having a plurality of land portions; a sleeve having the spool housed such that the spool is movable in an axial direction and has an input port and an output port and small-diameter portions in the interior of the sleeve. The pressure and flow rate of a fluid passing between the land portions and the small-diameter portions are adjusted by movement of the spool; a plurality of adjustment portions formed as spaces between the small-diameter portions of the sleeve and the land portions of the spool overlapping with each other from a radial direction of the spool; and a guide portion constituted by the small-diameter portion and the land portion which define one of the adjustment portions having a cross-sectional area smaller than each of cross-sectional areas of adjacent two of the adjustment portions having the input port interposed therebetween in the axial direction.