A steering device includes: a cylinder demarcated into first and second chambers by a piston; a main valve having first and second shuttle chambers; a hydraulic source having first and second discharge ports; a first oil passage configured to connect the first chamber and the first shuttle chamber; a second oil passage configured to connect the second chamber and the second shuttle chamber; a third oil passage configured to connect the first shuttle chamber and the first discharge port; a fourth oil passage configured to connect the second shuttle chamber and the second discharge port; and a tank connected to the main valve via the third oil passage and the fourth oil passage. One of the first shuttle chamber and the second shuttle chamber of the main valve is in an opened state when the hydraulic source is stopped.

A hydraulic power pack for use in a hydraulic system includes a reservoir configured to receive hydraulic fluid. A pump is in communication with the reservoir and is fluidly connectable to the hydraulic system. The pump is configured to pump hydraulic fluid from the reservoir into the hydraulic system when connected thereto. A hydraulic fluid sensor is fluidly connectable to the hydraulic system to sense a fluid characteristic of the hydraulic fluid within the hydraulic system. A variable speed drive is operatively coupled to the pump and the hydraulic fluid sensor to receive sensor data therefrom, with the variable speed drive being configured to generate a pump control signal based on the received sensor data. The pump is configured to operate at various speeds based on the pump control signal received from the variable speed drive.

A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.

A hydraulic stage includes a hydraulic element located between and sealing a first and second chamber, wherein the first chamber comprises at least one aperture through which fluid is arranged to flow into or out of the first chamber; and at least one piezoelectric element which is positioned adjacent to the at least one aperture and is arranged to deform in response to an applied potential difference such that it blocks or obstructs the at least one aperture to a varying degree according to the level of deformation, so as to control fluid flow into or out of the first chamber. The level of deformation of the piezoelectric element thus reduces or increases an effective size of the inlet or outlet aperture to which it is adjacent, restricting or permitting an increase in fluid flow accordingly.

The disclosure discloses an electro-hydraulic servo actuator capable of implementing long-stroke and high-frequency loading and a control method. The actuator includes: a long hydraulic cylinder with a piston, a short hydraulic cylinder with a piston, a fixed-end rod, low frequency and high frequency electro-hydraulic servo valves, a left rod chamber, a right rod chamber, a force applying end head, and a force applying end rod. With this structure, the displacement of the piston of the short hydraulic cylinder is a combination of small-displacement and high-frequency movement and large-displacement and low-frequency movement, so as to realize the generation of large-displacement and high-frequency movement. Therefore, a target large-displacement and high-frequency excitation is applied to the specimen under load test. The actuator can output high-frequency and large-displacement target excitation of 0.1 Hz to 200 Hz and 0 mm to 1500 mm, and has a simple mechanical structure, advanced control process, and good practicability.

A linear actuator system includes a linear actuator and at least one integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.

Provided is an electrohydrostatic actuation system including an emergency shut-off circuit to be actuated stably with a simple configuration. The electrohydrostatic actuation system includes: a hydraulic cylinder (24) including a piston (25) to which a valve element is connected, a first chamber (24A), and a second chamber (24B); a hydraulic pump (21) configured to supply hydraulic fluid to the first chamber (24A) or the second chamber (24B); a servo motor (M) configured to drive the hydraulic pump (21); a shuttle valve (11) configured to establish communication to a downstream side under a state in which a hydraulic pressure generated by the hydraulic pump (21) is maintained; a solenoid valve (12) configured to receive the hydraulic pressure via the shuttle valve (11) as a pilot pressure; and a logic valve (13) including a first port configured to receive the pilot pressure from the solenoid valve (12), and a second port to be communicated to the first chamber (24A) of the hydraulic cylinder (24). When the solenoid valve (12) is brought to a de-energized state, the pilot pressure of the logic valve (13) is released, and the logic valve (13) causes the hydraulic fluid in the first chamber (24A) communicated to the second port to flow into the second chamber (24B) so that emergency shut-off of the valve element is achieved by a return spring (26).

Provided is an actuator apparatus including a positioning actuator device configured to position a first carrier member of the actuator apparatus. The positioning actuator device includes a first hydraulic fluid actuator having a first clamping means and a second hydraulic fluid actuator having a second clamping means, wherein the first and second hydraulic fluid actuator are configured to alternately clamp around a guide arrangement for moving the positioning actuator device along the guide arrangement. The first carrier member is provided with a first coupling member configured to be releasable coupled to the positioning actuator device. A method of positioning a first carrier member by means of the positioning actuator device is provided.

A hydraulic circuit includes a prime mover that is configured to generate an oscillating flow of hydraulic fluid, and an actuator that is driven by the prime mover and configured to provide oscillating motion and to be connected to a load in each direction of the motion. The hydraulic circuit also includes a reclamation device that is disposed in the hydraulic circuit between the prime mover and the actuator. The reclamation device captures and stores a portion of hydraulic fluid displaced from the actuator during a transition between opposed motions, where the portion of hydraulic fluid corresponds to an amount of hydraulic fluid equal to a volume of fluid required to compensate for compression of fluid within the hydraulic circuit due to system pressure and load pressure. The stored fluid is used by the circuit in a subsequent motion.

Provided is a fluid actuator capable of safely driving a drive target. An air actuator using air as a working fluid includes an X-axis pressure sensor that measures air pressures PX+ and PX− along one drive axis, which drives a drive target in an X direction, a Y-axis pressure sensor that measures air pressures PY1+, PY1−, PY2+, and PY2− along two drive axes, which drive the drive target in a Y direction, and an acceleration detection unit that detects translational acceleration and rotational acceleration generated in the drive target on the basis of the measured air pressures PX+, PX−, PY1+, PY1−, PY2+, and PY2−.