A telescopic actuator comprising a cylinder (2) in which a rod (3) is mounted to slide along a sliding axis (X), the actuator including a locking member comprising a locking finger (10) that is movable along a locking direction (Y) that is perpendicular to the sliding axis, between a locking position in which an end (9) of the locking finger (10) is engaged in a groove (8) of the rod in order to lock the rod in position, and a retracted position in which the end of the finger is disengaged from the groove in order to release the rod, a locking indicator (20) being secured to the locking finger to be movable between a position indicating locking when the locking finger is in the locking position, and a position indicating unlocking when the locking finger is in the retracted position, the actuator being characterized in that the locking indicator is secured to the locking finger by a connection (22, 23, 24) suitable for being interrupted in the event of the end of the finger being broken off while the rod is locked, a thrust spring (25) being arranged in the locking finger to push the locking indicator towards the position indicating unlocking when said connection is interrupted.

A hydraulic park system includes a spool valve linked to a park mechanism. In some circumstances, a hold-out-of-park mechanism is utilized to hold the spool in position. To avoid wear on the aluminum spool, a steel saddle is inserted onto the spool between two lands such that the hold-out-of-park mechanism engages the steel saddle. The steel saddle is inserted from the side of the spool. To ensure that the hold-out-of-park engages the correct side of the saddle, the saddle must be held in a predefined circumferential position about the bore axis. The saddle is constrained from rotation about the spool axis by abutting flat surfaces on the spool and the saddle. The spool is constrained from rotation relative to the bore by the park mechanism.

A railroad switch device for moving railroad switch points is provided. The device includes a hydraulic unit comprising a hydraulic manifold, a hydraulic cylinder to provide constant forward movement and reverse movement, and a hydraulic circuit unit. The railroad switch device also includes a mechanical target to automatically indicate the position of a point rod, where the hydraulic unit is coupled to the point rod. Additionally, the railroad switch device includes a plurality of spring units to produce a continuous thrust force for holding the railroad switch points closed in forward position and reverse position, where the plurality of spring units control the target rotation to approximately 90 degrees. A plurality of proximity sensors detect the point rod position, and a power unit supplies hydraulic power to the hydraulic unit for moving the hydraulic cylinder.

The security unit ensures, by blocking the hydraulic flow, that the rod of a cylinder is held in position. It includes two preferably twinned isolation devices, each mounted on one of the hydraulic lines supplying fluid to a chamber of the cylinder. Each isolation device includes two series-connected ball-check valves allowing the flow in the direction of inlet of the fluid into the respective chamber; and a longitudinal, separate rod, inserted between the balls but not linked thereto, and capable of being slidably guided towards each of the balls and driving same. The rod is too short to contact both balls simultaneously when the two valves are closed; but it is sufficiently long to push the ball of the second valve, thereby causing it to open, when it slides under the pushing action of the ball of the first valve upon the latter being controlled to be opened.

An actuator assembly including a fail-fix system is provided. The actuator assembly includes an output shaft, an input drive assembly, and a piston assembly. The piston assembly includes a body surrounding a piston moveable within the body. The body defines a first end and a second end opposite thereof between which the piston is moveable within the body. The piston assembly includes a spring disposed at the first end between the body and the piston. The piston assembly includes a friction mechanism disposed at the second end of the piston opposite of the first end. An adjustable area is defined within the body between the second end of the piston and the input drive assembly.

A method for securing an aircraft landing gear wheel drive actuator in an open position of the wheel, the drive actuator being movably mounted on the landing gear between said open position in which it is remote from the wheel and an engaged position in which it cooperates with the wheel to ensure its rotational drive, a displacement actuator being coupled to the drive actuator to move same between the two positions, and a locking member being provided to lock the drive actuator in the open position. The method includes holding the controlled displacement actuator to move the drive actuator to the open position, while the drive actuator is locked in the open position.

A directional control system of a marine vessel includes a steering control member manually operated by a user and operationally connected to a direction-variation member acting on or in the water, such as at least one rudder blade or at least one outboard engine, the direction-variation member having an angular position that is controlled by the steering control member; and a locking system locking the free variation of the angular position of the direction-variation member, which can be activated and deactivated to allow the variation of angular position and carry out a directional change, the locking system including a hydraulic cylinder having a piston dividing the cylinder into two chambers, which are connected by a bypass circuit that can be opened and closed by a switching member.

A hydraulic lock for a hydraulic system includes a flow control valve and a second check valve. The flow control valve having a first inlet, a first outlet, a first check valve and a flow restrictor, each of the first check valve and the flow restrictor being communicably coupled to the first inlet and the first outlet and being arranged in parallel between the first inlet and the first outlet. The second check valve having a second inlet and a second outlet, the second inlet being communicably coupled to the first outlet, the second check valve further having a ball seating surface having an aperture there through, a ball, and a resilient member biasing the ball towards the ball seating surface to seal the aperture, the aperture being communicably coupled to the second inlet and the second outlet.

A hydraulic park system includes a spool valve linked to a park mechanism. In some circumstances, a hold-out-of-park mechanism is utilized to hold the spool in position. To avoid wear on the aluminum spool, a steel saddle is inserted onto the spool between two lands such that the hold-out-of-park mechanism engages the steel saddle. The steel saddle is inserted from the side of the spool. To ensure that the hold-out-of-park engages the correct side of the saddle, the saddle must be held in a predefined circumferential position about the bore axis. The saddle is constrained from rotation about the spool axis by abutting flat surfaces on the spool and the saddle. The spool is constrained from rotation relative to the bore by the park mechanism.

In order to secure a reached extension position of a piston rod (22, 22) of an in particular multi stage operating cylinder device (100) with at least one operating cylinder unit (50) not only through the operating pressure in the cylinder (1, 1) of the operating cylinder unit (50) but additionally mechanically, a mechanical safety through interlocking safety elements (4a, b) in the interior of the operating cylinder device (100) is provided which is activated exclusively by the operating pressure in the first pressure cavity and disengaged by a pressure in a second operating cavity.