The present invention regards a fluid actuator arrangement comprising a first and second cylinder of a cylinder arrangement, a piston rod arrangement, a first and second piston device associated with the piston rod arrangement, wherein respective first and second piston device divides respective first and second cylinder into a first and second chamber provided for connection to a valve device of a fluid supply device. The first piston device comprises a piston rod engagement and disengagement device, which is adapted to engage or disengage the first piston device to/from the piston rod arrangement. The invention can be put into use for aircraft, such as commercial aircraft designed for long distance flights, for construction industry, jacking systems for oil well drilling and service platforms, agricultural equipment industry, marine industry, crane manufacture industry, and others.

The invention relates to a hydraulic drive (1) comprising a working cylinder (2) and a travel cylinder (3) which is mechanically connected to the working cylinder (2). The working cylinder (2) and the travel cylinder (3) each comprise an upper and a lower cylinder chamber (21, 22, 31, 32), and all four cylinder chambers (21, 22, 31, 32) of the working and travel cylinder (2, 3) are connected to one another in a suitable manner in a closed pressure circuit (4) which is filled and prestressed with a hydraulic fluid (F). A rotational speed-variable hydraulic machine (5) with a first and second pressure connection (51, 52) is arranged in the pressure circuit (4) in order to conduct the hydraulic fluid (F) between the individual cylinder chambers (21, 22, 31, 32) of the working and travel cylinder (2, 3) during the operation (B) of the hydraulic drive (1). At least one first and second distributing valve (6, 7) are arranged in the pressure circuit (4) such that the respective valve switch positions (61, 62, 71, 72, 73) which are suitable for the different operating phases of the hydraulic drive (1) together with the suitably driven hydraulic machine (5) allow a common movement of the work and travel cylinder (2, 3) in one or the other piston movement direction (R1, R2). For this purpose, preferably only the first and the second distributing valve (6, 7) are arranged in the pressure circuit (4). The hydraulic drive (1) requires a minimum number of components, maintains a low installation complexity, improves the energy efficiency, can be constructed in a compact manner, and can be operated in a sufficiently variable manner.

An apparatus for actuating a valve includes a first actuator having a first actuator housing and second actuator with a second actuator housing. A first plate is positioned within the first actuator housing and a second plate is positioned within the second actuator housing. An intermediate stem extends from a first pressure chamber of the first actuator housing to the second plate. A pressure media path extends through the intermediate stem and a second seal nut that extends into the second plate, the pressure media path providing fluid communication between the first pressure chamber, and a second pressure chamber of the second actuator housing. An injection port is open into one of the first pressure chamber and the second pressure chamber. The first plate and the second plate are movable in response to pressure media injected into the injection port, for actuating the valve.

An actuator includes a primary piston and a secondary piston axially movable together in a cylinder assembly; a plurality of chambers comprising: a first chamber, a second chamber, a third chamber, and a fourth chamber, wherein when fluid flows into the first chamber the primary piston extends and when fluid flows into the second chamber the primary piston retracts, wherein an extension fluid force applied by fluid in the third chamber to extend the secondary piston is different from a retraction fluid force applied by fluid in the fourth chamber to retract the secondary piston; and a force-balance chamber configured to receive fluid from the third chamber or the fourth chamber to apply a balancing force on the secondary piston to either oppose fluid force acting on the secondary piston or add to the fluid force acting on the secondary piston, thereby compensating for a difference between the extension fluid force and the retraction fluid force.