Actuator equipped with a no back system with inhibition zone

1. A nacelle, comprising:

a thrust reverser having a movable surface having sealing gaskets extending between the movable surface and the nacelle, the movable surface being connected to an actuator, said actuator comprising:

a body;

a screw that is rotatably mounted on the body;

a nut that is provided with connection means for connecting it to an element for moving, and that is engaged on the screw to be moved by the screw rotating between an over-retracted first position in which the sealing gaskets are flattened by the movable surface and a deployed second position on either side of a retracted third position, in said retracted third position the movable surface bears against the sealing gaskets, so that an outside surface of the movable surface is flush with an outside surface of the nacelle, said third position being spaced apart from the over-retracted first position by a distance corresponding to the screw rotating through a first angular sector; and

an anti-extension device comprising a friction disk free to rotate relative to the screw and designed to use friction to brake a portion constrained to rotate with the screw when the element for moving exerts a traction force on the nut tending to move the nut towards the deployed second position,

wherein the friction disk has at least one smooth surface and only two obstacles arranged in the smooth surface both for co-operating with at least one pawl connected to the body, thereby defining both at least one second angular sector of free rotation for the friction disk in a predetermined direction and also a position for blocking the friction disk in this predetermined direction, the smooth surface having a length such that the amplitude of the first angular sector is strictly less than the amplitude of the second angular sector.

2. The nacelle according to claim 1 , wherein the portion constrained to rotate with the screw comprises a bushing slidably mounted on the screw.

3. The nacelle according to claim 2 , wherein the bushing includes a straight portion extending coaxially about the axis of rotation of the screw, and the friction disk is slidably mounted on the straight portion of the bushing.

4. The nacelle according to claim 1 , wherein the anti-extension device comprises a first abutment disk provided with rollers having respective axes of rotation that extend radially with respect to the rollers, the first abutment disk being mounted free to rotate about the screw.

5. The nacelle according to claim 4 , wherein the anti-extension device comprises a second abutment disk provided with rollers having respective axes of rotation that extend radially with respect to the rollers, the second disk being mounted to rotate freely about the screw.

6. The nacelle according to claim 1 , wherein the anti-extension device comprises a skew roller disk mounted free to rotate about the screw and provided with rollers having respective axes of rotation that extend in directions that form a non-zero angle (a) with a radial direction passing through one of the ends of the roller, the skew roller disk extending between the friction disk and the portion constrained to rotate with the screw.

7. The nacelle according to claim 1 , wherein the smooth surface is situated at the periphery of the friction disk.

8. The nacelle according to claim 1 , wherein the friction disk co-operates with two pawls.