A method of controlling an actuator includes switching a primary solenoid valve to a first mode to fluidically connect a supply pressure source to a control chamber of a pilot valve. A fluid from the supply pressure source is directed through the primary solenoid valve to fill the control chamber of the pilot valve and put the pilot valve in a first position. The first position fluidically connects a second chamber of the actuator to a return pressure source. The actuator includes a cylinder between the first chamber and the second chamber and a rod attached to the cylinder. The fluid from the supply pressure source is directed into the first chamber of the actuator to move the cylinder and the rod in a first direction while the pilot valve is in the first position.

In accordance with one embodiment of the present disclosure, a material moving machine comprises a pilot hydraulic switching system. The pilot hydraulic switching system comprises a control unit, a first directional valve, and a second directional valve. The control unit is configured to operate the first and second directional valves to shift a variable position actuator valve between a static state, a retract state, and an extend state. The actuator valve comprises a first and second control element. In the retract and extend states, the first and second directional valves control fluid flow to the variable position actuator valve with a positive net pressure on either the first or second control elements and a negative net pressure on the other control element to move the material moving implement. In the static state, the first and second directional valves control fluid flow equally on the first and second control elements.

A servovalve having a pilot stage includes two hydraulic elements that are movable relative to each other so as to move a power-directing member, the pilot stage including a linear actuator having a main pusher arranged to modify the relative position of the hydraulic elements. The pilot stage has a position feedback lever.

The subject matter of this specification can be embodied in, among other things, a method that includes controlling, by a first fluid valve, a first fluid flow to a first fluid actuator, actuating, by the first fluid actuator, an output, controlling, by a second fluid valve, a second fluid flow to a second fluid actuator, and actuating, by the second fluid actuator, the output.

A piezoelectric ring bender servo valve assembly reduces mechanical wear by removing mechanical components used in prior art servo valves. The assembly does not use torque motor, flapper, and feedback spring. In this manner, no moving parts are required, which reduces maintenance and costs. A pair of piezoelectric ring benders mount adjacently to a pair of nozzles. The piezoelectric ring benders independently regulate the flow of fluid through the nozzles by moving between an open position to enable flowage, and a closed position to restrict flowage. A linear position sensing device measures and provides feedback about the spool position to a valve controller. The valve controller allows the spool valve to move until valve position achieves command position and the force on the spool valve is in equilibrium with pressure difference across spool valve. An H-bridge operable to switch the polarity of a differential pressure applied across to a load.

A servovalve system comprising a pilot stage valve in communication with an hydraulic stage valve, the hydraulic stage valve comprising a valve member movably mounted in a valve chamber to selectively meter fluid flow in a flow path from an upstream inlet port to a downstream outlet port and at least two variable-sized orifices disposed in the flow path between the inlet and outlet ports, an upstream pressure sensor, a downstream pressure sensor, a fluid temperature sensor, a position sensor sensing a linear position of the valve member, a controller that receives input from the upstream pressure sensor, the downstream pressure sensor, the fluid temperature sensor and the position sensor; and the controller configured to provide a control signal to the pilot stage valve as a function of the input from the upstream pressure sensor, the downstream pressure sensor, the fluid temperature sensor and the position sensor.

An amplifier is configured for use in a control valve. These configurations provide a pneumatic signal to an actuator that regulates flow through the device. The amplifier may include a variable orifice, or bleed valve, that moves in response to changes in actuating media around steady state. This bleed valve prevents bleed of actuating media at steady state. This feature reduces energy consumption or emissions from the control valve.

A servo valve comprises a valve housing, a cavity formed in the valve housing and a member disposed in the cavity and axially-moveable therein. The servo valve further comprises a piezoelectric actuator configured to axially move the member, relative to the valve housing, between first and second axial positions.

An energy saving directional-control valves (2-position and 3-position) are configured with standard manual override functionality and with the same steady-state input-output behavior as each respective standard/non-energy saving directional-control valve. This allows a standard non-energy saving valve to be replaced with an energy saving valve without reconfiguring the external electrical and manual override command logic.

An energy saving directional-control valves (2-position and 3-position) are configured with standard manual override functionality and with the same steady-state input-output behavior as each respective standard/non-energy saving directional-control valve. This allows a standard non-energy saving valve to be replaced with an energy saving valve without reconfiguring the external electrical and manual override command logic.