A propeller hydraulic actuation system, includes a double-acting dual chamber hydraulic pitch change actuator. The pitch change actuator includes a first pressure circuit having first fluid supply lines and a first hydraulic chamber and a second pressure circuit having second fluid supply lines and a second hydraulic chamber. A piston separates the first and second chambers. At least one pressure sensor is provided for obtaining pressure measurements from which a load differential (F) applied to the piston by the circuits can be calculated. A closed loop controller is arranged to control the fluid supplied to the first and second pressure circuits, wherein the closed loop controller includes an actuator position loop arranged to utilise feedback on the actuator position to control the actuator position.

A valve has a housing which has at least two fluid openings, through which fluid can flow, and a further opening, at least one valve seat which is assigned to one of the fluid openings, and at least one closure member which is adjustable to release and/or close the at least one valve seat, the at least one valve seat which adjoins a cavity through which fluid can flow being formed on a housing part. The valve includes a sensor device which closes the opening in a fluid-tight manner and can acquire data about the fluid is arranged in the further opening. A valve island is furthermore described.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.

An in-port sequencing valve configured to be utilized with a clamping device of a workpiece clamping system having a fixture plate, a number of fixture datums, and a number of clamping devices. The in-port sequencing valve includes a housing, a pre-load adjuster, a valve spring, and a valve piston. The pre-load adjuster is configured to be set to a selected valve activation setting. The valve spring is compressed an amount corresponding to the valve activation setting. The valve piston is configured to be shifted from a closed position to an open position when a force due to hydraulic fluid pressure overcomes a threshold spring force of the valve spring corresponding to the valve activation setting. The in-port sequencing valve can be set to a selected valve activation setting so that the clamping devices clamp the workpiece in a selected order according to the valve activation setting.

Electrically controllable hydraulic system for a vehicle transmission and method for controlling the same An electrically controllable hydraulic system (1) for a vehicle transmission comprises a pressure pump system (4a, 4b) and a subsystem (1A) comprising a transmission element (2) and an electrically controlled hydraulic pressure controlling module (1B) including a hydraulic valve element (15) for controlling a hydraulic pressure for actuating the transmission element (2) and an electromagnetically controllable operating element (21) for operating the hydraulic valve element (15). The subsystem (1A) and the pressure controlling module (1B) have a first and a second cut-off frequency (f1, f2) with f2>f1. The hydraulic system includes a driver circuit (32) for driving the pressure controlling module (1B) that comprises a full bridge circuit and a control circuit (42) for simultaneously controlling both switching elements of the driver circuit with a duty cycle according to an input value of the input signal (lset) dithered with a frequency (f.sub.dith) in the range (f1, f2).

A valve has a housing which has at least two fluid openings, through which fluid can flow, and a further opening, at least one valve seat which is assigned to one of the fluid openings, and at least one closure member which is adjustable to release and/or close the at least one valve seat, the at least one valve seat which adjoins a cavity through which fluid can flow being formed on a housing part. The valve includes a sensor device which closes the opening in a fluid-tight manner and can acquire data about the fluid is arranged in the further opening. A valve island is furthermore described.

A pressure control device is provided and includes a body which has a groove-shaped flow path including a groove part and a widened part connected to the groove part and having a width larger than a width of the groove part, and a filter unit which captures foreign matters mixed in a fluid which passes through the groove-shaped flow path. The filter unit includes a frame body being in a cylindrical shape and including a through hole part which penetrates in a direction along a central axis, and at least one filter member being in a planar plate shape disposed to intercept the through hole part and supported inside the frame body, in which the filter unit is accommodated in the widened part so that a direction orthogonal to the central axis of the frame body is along a depth direction of the widened part.

A hydraulic drive apparatus for an industrial vehicle includes a cargo-handling device, a hydraulic control device, a cargo-handling-device operating member, and a switching member. When a first operation of the cargo-handling-device operating member is performed, an open-close valve is opened to hydraulic oil flowing in a first direction to cause the hydraulic oil to bypass a throttle. When a second operation of the cargo-handling-device operating member is performed while the switching member is in a first state, the open-close valve is closed against hydraulic oil flowing in a second direction to cause the hydraulic oil to flow through the throttle. The throttle provided in a flow route of the hydraulic oil between a main control valve and the cargo-handling device reduces a flow rate of the hydraulic oil to restrict cargo handling.

A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.