Linear actuator

A linear actuator having:

• an outer tubular body extending along an axis and having internally at least one helical rolling track;
• an inner tubular body which can move in translation inside the outer tubular body, coaxial thereto, and accommodating internally a motor for driving in rotation a shaft which is coaxial with the tubular bodies;
• at least one nut which is mounted on this shaft and can move in rotation and in translation inside the outer tubular body and has, on the one hand, at least one helical rolling path which extends around this nut and is provided with two ends and, on the other hand, a recirculation zone joining the two ends of such a rolling path;
• balls arranged between a rolling path of at least one nut and a rolling track of the outer tubular body, and in the recirculation zone of such a nut, characterized in that the actuator has:
• at least one bearing means which, on the one hand, consists of a pad with a cylindrical general shape made integral with and fixed to the shaft and having at least one helical thread extending around this pad and, on the other hand, is designed so as to bear against a rolling track of the outer tubular body along at least one line of contact;
• at least one control means for this bearing means, this control means having, on the one hand, a means for mounting the nut or nuts on the shaft so as to be fixed in rotation and movable in translation and, on the other hand, axially and on either side of such a nut, at least one means for exerting a prestress on such a nut, this control means being designed, on the one hand, to hold such a bearing means in an inactive bearing position in which there is a clearance between this bearing means and the rolling track and, on the other hand, to cause such a bearing means to take up an active bearing position on the rolling track, this taking place under the effect of an axial stress, greater than a threshold stress, exerted on the actuator.