A linear electro-mechanical actuator, comprising: - a containment structure; - a pusher designed to translate relative to the containment structure in such a way that it at least partly comes out of the containment structure during actuator operation; - a nut located in the containment structure and able to rotate about an axis driven by a driving force; - a screw shaft inserted in the nut and connected to the pusher, said screw shaft being interconnected with the nut by means of a helical recirculating ball coupling in such a way that a rotation of the nut causes a translation of the screw shaft along said axis; - an anti-rotation mechanism acting on the screw shaft to prevent the screw shaft from rotating about said axis; wherein said screw shaft comprises a cavity positioned about the axis and wherein said anti-rotation mechanism comprises a guide unit fixed to the containment structure and inserted in said cavity in the screw shaft, said guide unit being coupled in a non-rotational fashion to the screw shaft; wherein said guide unit is coupled in a non-rotational fashion to the screw shaft by means of a recirculating ball coupling designed to allow a translation of the screw shaft relative to the guide unit along the axis, and wherein the recirculating ball coupling extends on a closed path comprising a first stretch parallel with the axis and interposed between the guide unit and the screw shaft, for forming a sliding coupling between the guide unit and the screw shaft, and a second stretch made inside the guide unit for the recirculation of the balls, and a pair of third stretches connecting the first and second stretches (R1, R2), characterised in that the guide unit comprises: - a first portion fixed to the containment structure; - a second portion removably connected to the first portion and comprising longitudinal outer grooves, forming said first stretch of the closed path, and inner channels for recirculation of the balls forming the second stretch of the closed path; and - a third portion removably fixed to the second portion; and wherein the first and third portions (10a, 10c) comprise, on a respective interface with the second portion, diverter elements for conveying the balls between each inner channel and a respective longitudinal outer groove. - a containment structure; - a pusher designed to translate relative to the containment structure in such a way that it at least partly comes out of the containment structure during actuator operation; - a nut located in the containment structure and able to rotate about an axis driven by a driving force; - a screw shaft inserted in the nut and connected to the pusher, said screw shaft being interconnected with the nut by means of a helical recirculating ball coupling in such a way that a rotation of the nut causes a translation of the screw shaft along said axis; - an anti-rotation mechanism acting on the screw shaft to prevent the screw shaft from rotating about said axis; - a first portion fixed to the containment structure; - a second portion removably connected to the first portion and comprising longitudinal outer grooves, forming said first stretch of the closed path, and inner channels for recirculation of the balls forming the second stretch of the closed path; and - a third portion removably fixed to the second portion;