A fluid pump for a linear actuator causes a rod in the actuator to extend or retract by controlling fluid flow to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes check valves that control fluid flow between a driven pump element and each portion of the fluid chamber and a shuttle movable in response to fluid pressure along a shuttle axis extending through the valves. At least one valve includes a valve member movable between a closed position and an open position defining a fluid flow path between the driven pump element and fluid chamber and means for limiting movement of the shuttle towards the valve such that the shuttle may, depending on the position of the limiting means, move the valve member to an intermediate position between the closed and open positions.

A fluid pump for a linear actuator causes a rod in the actuator to extend or retract by controlling fluid flow to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes check valves that control fluid flow between a driven pump element and each portion of the fluid chamber and a shuttle movable in response to fluid pressure along a shuttle axis extending through the valves. At least one valve includes a valve member movable between a closed position and an open position defining a fluid flow path between the driven pump element and fluid chamber and means for limiting movement of the shuttle towards the valve such that the shuttle may, depending on the position of the limiting means, move the valve member to an intermediate position between the closed and open positions.

A pneumatic unit for a hydropneumatic pressure booster has a system line that leads from a compressed air inlet to a compressed air outlet. A bypass line runs parallel to the system line and it is connected to the system line via first and second compressed air switches. A compressed air reservoir is connected in the bypass line, and a pressure intensifier is connected in the region between the first compressed air switch and the compressed air reservoir. The pneumatic unit makes available to the pressure booster a sufficiently high pneumatic pressure for carrying out at least one operational step of a connected hydraulic tool, even in the case of a pressure decrease or pressure failure in the supplying pneumatic line. For that purpose, the second compressed air switch is configured for switching the compressed air flow between the system line and the bypass line.

Systems, methods and devices are described providing a selective hydraulic or electrically powered prime mover that is a bi-directional power unit system, including movement within a device used to compress and/or expand a fluid and provide fluid movement. The use of a hydraulic power unit is involved and comprises at least a pump or other fluid moving device, a first set of selective control valves delivering pressurized fluid to the device(s), and a second set of selective control valves returning unpressurized fluid from the device(s), a reservoir comprising a compensator tank, a port for operation at ambient pressure, and a pressure measuring device measuring ambient pressure allowing for unbalanced flow to and from the device as well as thermal expansion or compression. The use of a multiport and in some cases a swashplate pump that incorporates the features and functions of several valves for the system is also described.

A method for paving wherein the paving operator or a person in the vicinity of the paver remotely controls the flow of paving material from a dump truck into the hopper of the paver.

A valve system including a shuttle valve having first and second inlet channels connected respectively to first and second channels, a cavity, an outlet channel and a moveable element, the first and second inlet channels being in fluid communication with outlet channel via the cavity; wherein a moveable element is moveable within the cavity such that the position of the moveable element is determined by relative pressure levels in the first and second inlet channels, in a first position the movable element forming a seal between the moveable element and the first inlet channel, in a second position the moveable element forming a seal between the moveable element and the second inlet channel, and in a third position the moveable element being located between the first and second positions and allowing the passage of fluid from both the first and second channels.

A braking system for use with a dual landing gear aircraft. The braking system pairs outboard brake control into an outboard brake system control unit (BSCU) and inboard brake control into a second inboard brake system control unit (BSCU). Each BSCU is designed with two independent control lanes in which the forward wheel set is paired in one control lane and the aft wheels are paired onto the other. Alternate braking is provided via an alternate brake module installed in a fore-aft wheel pairing.

The invention relates to a pressure-limiting device designed to be installed in a system comprising a first line (11) and a second line (12) that can comprise pressurised oil, as well as comprising a discharge and/or booster line (10). The device also comprises a pressure selector (130, 150) in the form of a cage defining two seats (132, 134) and two pressure relief valves (160, 180). The limiting device is characterised in that it further comprises at least one means (170, 172; 190, 192) for regulating a pressure relief valve, disposed on the outside of an axial end of the pressure selector (150), in the form of a cage that allows the loading of the associated pressure relief valve to be regulated.

A method controls a hydraulic actuator drive that has an actuator and the position of the actuator is set by at least one electrohydraulic proportional valve that has at least one electrical input and at least one hydraulic output. First, the position of the actuator is detected and an actual position value is generated therefrom. Second, a target position value is specified in dependence on a default for a desired position of the actuator and a target/actual value difference is corrected by the at least one electrohydraulic proportional valve, so that the actuator assumes a position corresponding to the target position value. The method is characterized in that the target position value is also varied if the default remains unchanged for a desired position of the actuator.

Hydraulic circuits for controlling a movable component use one or more of a plurality of fluid supplies. Pressurized fluid flowing from one supply is routed toward the component and is not inadvertently vented into another fluid supply, or into an exit port. A backflow path is provided for fluid returning from the hydraulic component when the component is actuated in a reversed direction. The hydraulic circuits can be used, for example, on blowout preventers in a subsea environment.