An asymmetric linear actuator is provided which integrates a hydraulic dissipater and an electric motor and power screw which generates small forces. The actuator is configured so that an electric motor drives a power screw which drives a rod through a cylinder to provide linear actuation. The cylinder is fluid-filled and incorporates a piston that separates the cylinder into a first and second fluid chamber which are filled with a first and second volume of working fluid. Movement of the piston and rod assembly results in fluid movement between the first and second volumes of working fluid and through the fluidic restriction. The fluidic restriction can be proportionally controllable via an electric motor which enables controllable power dissipation via control of the fluidic restriction motor and controllable power generation via control of the power screw motor.

A cylinder actuator includes a body assembly and a piston assembly. The body assembly includes a first cylinder nested concentrically within a second cylinder. The piston assembly slides linearly within the first and second cylinders. The piston assembly includes a first piston assembly end and a second piston assembly end. The first piston assembly end includes first and second pistons. The first piston moves within the first cylinder. The second piston moves within the second cylinder. The piston assembly includes first and second piston rods. The first piston rod extends from the first piston through a first end of the first cylinder. The second piston rod extends from the second piston through a first end of the second cylinder. The piston rods are joined at the second end of the piston rod assembly located outside of the first and second cylinders.

An asymmetric linear actuator is provided which integrates a hydraulic dissipater and an electric motor and power screw which generates small forces. The actuator is configured so that an electric motor drives a power screw which drives a rod through a cylinder to provide linear actuation. The cylinder is fluid-filled and incorporates a piston that separates the cylinder into a first and second fluid chamber which are filled with a first and second volume of working fluid. Movement of the piston and rod assembly results in fluid movement between the first and second volumes of working fluid and through the fluidic restriction. The fluidic restriction can be proportionally controllable via an electric motor which enables controllable power dissipation via control of the fluidic restriction motor and controllable power generation via control of the power screw motor.

An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.

A servo brake cylinder for a distributed brake system with an electric motor, a ball screw assembly with a lead screw and a nut, a piston, a cylinder body is disclosed. The electric motor is connected to the ball screw assembly. The piston is installed in the hollow inner space of the cylinder body, slidable axially. The piston has a hole at the center formed by three sections of surfaces including a first cone surface, a cylindrical surface a second cone surface. One end of the lead screw is connected with the nut, and the other end at the tip of the lead screw has three sections of surfaces including a gradually constricting cone surface from the tip followed by a cylindrical surface, further followed by a gradually expanding cone surface. These surface sections at the lead screw and the three sections of the surfaces at the hole of the piston form an inlet valve and an outlet valve between the piston and the lead screw.

The subject matter of this specification can be embodied in, among other things, an assembly that includes a piston having a piston inner surface defining a cylindrical cavity and includes a first axial portion, a piston face at a first end of the first axial portion, a second axial portion at a second end of the first axial portion, and a helical piston thread defined upon the piston inner surface, a bushing configured to contact the piston inner surface, and a lock nut configured to engage the piston and the bushing.

A servo brake cylinder for a distributed brake system with an electric motor, a ball screw assembly with a lead screw and a nut, a piston, a cylinder body is disclosed. The electric motor is connected to the ball screw assembly. The piston is installed in the hollow inner space of the cylinder body, slidable axially. The piston has a hole at the center formed by three sections of surfaces including a first cone surface, a cylindrical surface a second cone surface. One end of the lead screw is connected with the nut, and the other end at the tip of the lead screw has three sections of surfaces including a gradually constricting cone surface from the tip followed by a cylindrical surface, further followed by a gradually expanding cone surface. These surface sections at the lead screw and the three sections of the surfaces at the hole of the piston form an inlet valve and an outlet valve between the piston and the lead screw.

An electro-hydraulic linear lead screw actuator preferably includes an electric motor device, a hydraulic tube, an actuator lead screw, an actuator screw nut, an actuator rod and at least one external hydraulic flow passage. The actuator lead screw is rotated by the electric motor device. The actuator screw nut preferably includes a piston portion, a first screw nut portion and a second screw nut portion. A lead screw thread is formed through the first and second screw nut portions to threadably receive the actuator lead screw. The actuator rod is retained on the piston portion. Rotation of the electric motor device causes the actuator rod to extend or retract. A first hydraulic chamber is located behind the piston portion and a second hydraulic chamber is located in front of the piston portion. At least one external hydraulic flow passage transfers hydraulic fluid between the first and second chambers.

An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.

A lockable actuator includes: a body; a screw for pivoting relative to the body; a nut engaged on the screw so as to move along the screw between an over-retracted first position and a deployed second position on opposite sides of a retracted third position; a sleeve constrained to rotate with the screw and slidably mounted thereon in order to be moved by the nut; and an obstacle secured to the sleeve and a pawl capable of passing collectively between an active state and an inactive state, the pawl and the obstacle being arranged in such a manner that the pawl in its active state can co-operate with the obstacle only after the nut has been moved through a predetermined distance from its third position towards its second position.