This hydraulic system is provided with: a hydraulic pump; a pilot-type control valve; an electromagnetic proportional valve; a controller; and a pilot pressure switching unit which is capable of switching the electromagnetic proportional valve supply pressure to a first pressure during a normal operation, or to a second pressure lower than the first pressure. The control valve is provided with a bleed-off passage, and is capable of controlling the operating oil pressure supplied to the actuator, according to the opening area thereof. During an emergency operation, the electromagnetic proportional valve supply pressure is switched from the first pressure to the second pressure, the electromagnetic proportional valve is brought into a fully opened state, and the operating oil discharge amount from the hydraulic pump increases and decreases, and the operating oil pressure increases and decreases, and thus the operating speed of the actuator is controlled.

A fluid leakage detection system includes: a measurement unit configured to detect leakage of working oil in a hydraulic cylinder; and a controller configured to acquire a measurement result from the measurement unit, wherein the controller diagnoses that a battery depletion has been caused in a battery in a case in which it is determined that a data from the measurement unit has not been acquired and it is determined that the battery of the measurement unit has been in a low-remaining-battery-level state, and the controller diagnoses that a communication abnormality has been caused in a first communication part of the measurement unit in a case in which it is determined that the data from the measurement unit has not been acquired and it is determined that the battery has not been in the low-remaining-battery-level state.

In a steam valve driving apparatus according to an embodiment, a control valve permits or blocks a flow of hydraulic oil from a supply port to an opening direction piston chamber. A dump valve blocks or permits the flow of the hydraulic oil from the opening direction piston chamber to a discharge port. A blocking valve permits or blocks a flow of the hydraulic oil from an accumulator to a closing direction piston chamber. The control valve permits the flow of control oil from the closing direction piston chamber to the discharge port in a state where the flow of hydraulic oil from the supply port to the opening direction piston chamber is permitted.

An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.

A method of operating a fail-fixed hydraulic actuator system is provided. The method includes providing an actuator in an initial position, electromechanically operating a valve assembly to hydraulically drive actuator movement and halting the hydraulic driving of the actuator movement by the valve assembly.

A valve arrangement for a fluidic supply of a fluid load, with several main valves designed for influencing fluid flows at the fluid ports, and with electrically controllable pilot valves designed for fluidic control of the main valves. A base body is assigned a connection plate lying opposite a connection face and having a fluid passage which leads into an operating port for the connection of a fluid load wherein, between the connection face and the connection plate there is provided a separate passage body which has at least one connection passage for a fluidically communicating link between at least one of the fluid ports and the operating port, and at least one connecting conduit for a fluidic coupling of at least two fluid ports.

An apparatus for controlling a hydraulic machine, for example a turbine, pump or pump turbine, using variable-speed driven fixed displacement pumps. The apparatus includes a device for carrying out an emergency shut-off that is characterized by low energy consumption and high efficiency while guaranteeing all the operation-relevant and safety-relevant requirements of a hydraulic machine.

A failsafe vale provides Hole-In-The-Wall failsafe functionality for thin-wing aircraft control surface actuation systems having a geared rotary actuator powered by a hydraulic rotary motor. The failsafe valve is associated with the hydraulic rotary motor and mechanically connected to the control surface, and enables the flight control surface to return to an aerodynamically neutral failsafe position if electrical control and/or hydraulic pressure is lost. When the failsafe valve receives a normal command pressure from the hydraulic system, the valve is inactive and the actuation system operates normally. However, if there is a loss of electrical command capacity to control hydraulic valves and/or a loss of hydraulic pressure, the failsafe valve is activated and connects one of the motor hydraulic control lines to the case return line for the motor if the control surface is away from its failsafe position. Consequently, the control surface will be hydraulically powered or aerodynamically ratcheted to its failsafe position in the failure event.

A dual spool valve and methods of controlling hydraulic fluid that is moved to a hydraulic actuator of an aircraft. The dual spool valve may include ports to receive and discharge hydraulic fluid. The dual spool valve may also include first and second valve sections that are selectively positionable to control the flow of hydraulic fluid into and out of the actuator. One position provides for hydraulic fluid to move through closure lines. Method of controlling the dual spool valve may provide for selectively positioning the valve sections to control the flow of hydraulic fluid, and to position the valve sections to move hydraulic fluid through a closure line during certain circumstances.

Distributed trailing edge wing flap systems are described. An example wing flap system for an aircraft includes a flap and an actuator. The flap is movable between a deployed position and a retracted position relative to a fixed trailing edge of a wing of the aircraft. The actuator is to move the flap relative to the fixed trailing edge. The actuator is hydraulically drivable via first pressurized hydraulic fluid to be supplied by a hydraulic system of the aircraft. The actuator is also hydraulically drivable via second pressurized hydraulic fluid to be supplied by a local power unit. The local power unit is selectively connectable to an electrical system of the aircraft. The electrical system is to power the local power unit to supply the second pressurized hydraulic fluid.