There is disclosed a linear actuator comprising: a screw shaft comprising a screw thread and having a longitudinal axis A; a nut movable along the screw shaft from a retracted position to an extended position; and a plurality of rollers movable with the nut, each comprising a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the flank(s) so that the nut translates in an axial direction along the screw shaft; wherein the screw thread comprises one or more detents (e.g., grooves) configured to lock the nut in one or more axial positions.

An actuator includes a housing, a first nut in the housing, a second nut in the housing, and a threaded spindle screwed into the first nut and the second nut. The first nut exerts a first force in a first direction on the threaded spindle, and the second nut exerts a second force in a second direction on the threaded spindle, the first direction being different than the second direction.

An improvement of a worm gear speed reducer is provided where the output gear is substituted by a threaded chain comprised of nut-like threaded bodies mounted on the extended rods of two parallel endless chains, thus the contact surfaces of the drive screw and the threaded chain are much greater than the contact surfaces of the worm gear reducer, and thus the load capacity and wear resistance are much higher. The screw applies the driving force at the centroid of the contact surface of the threaded chain. There are three embodiments which may be a roller screw, a ball screw or a plain translation screw. With the roller screw or the ball screw there is rolling contact and thus the efficiency of the present invention is higher than that of the worm gear reducer which permits it to be used as an amplifier.

An actuator system for a flight control surface of an aerial vehicle includes a motor, and an inner shaft. The inner shaft includes a first portion at a first end and a second portion that extends from the first portion to a second end of the inner shaft. The first portion of the inner shaft is coupled to the motor. The second portion of the inner shaft is coupled to at least one roller that includes roller threads. The actuator system includes an inverted nut defining an inner bore and having an outer diameter that defines an output rod. The inner bore includes nut threads. The inverted nut is coupled about the inner shaft such that the nut threads are to engage with the plurality of roller threads to move the output rod, and the output rod is to be coupled to the flight control surface.

An actuator system for a flight control surface of an aerial vehicle includes a motor, and an inner shaft. The inner shaft includes a first portion at a first end and a second portion that extends from the first portion to a second end of the inner shaft. The first portion of the inner shaft is coupled to the motor. The second portion of the inner shaft is coupled to at least one roller that includes roller threads. The actuator system includes an inverted nut defining an inner bore and having an outer diameter that defines an output rod. The inner bore includes nut threads. The inverted nut is coupled about the inner shaft such that the nut threads are to engage with the plurality of roller threads to move the output rod, and the output rod is to be coupled to the flight control surface.

A planetary roller screw arrangement is provided includes a threaded nut, a threaded spindle, and a plurality of threaded planets. The threaded nut has a first longitudinal length and a first threaded portion that spans a second longitudinal length. The threaded spindle has a second threaded portion that spans a third longitudinal length. The plurality of threaded planets are arranged radially between the threaded spindle and the threaded nut and have a third threaded portion configured to be threadedly engaged with the first threaded portion, the third threaded portion spanning a fourth longitudinal length. The fourth longitudinal length is greater than the third longitudinal length.