There is described an actuator (1) comprising an outer tube (5) and an inner tube (11). In the actuator there is provided a spindle (2) co-operating with a bushing (8) for creating the displacement of the actuator by means of a motor (4). In order to establish an end stop in a secure way for preventing a wedging of the spindle (2) and the bushing (8) in extreme positions for the actuator (1), the bushing (8) is disposed rotatable in relation to both tubes as it is arranged rotatable in a bushing housing (9). The actuator is arranged so that friction between the bushing (8) and the bushing housing (9) is greater that the friction occurring between the spindle (2) and the bushing (8). Hereby rotation of the spindle will displace the bushing along the spindle until it reaches an extreme position. By an extreme position a pin (22) on the bushing will hit a pin (27) mounted in the spindle. At contact between the two pins the friction between the bushing and the housing (9) is overcome, whereby the bushing will perform a continuous rotation together with the spindle without any risk of its wedging against and end face in the tubes (5, 11).