Controlled-friction linear device in which a press force is applied perpendicular to the movement

1. A controlled-friction device comprising:

a first element having a second element mounted thereon to slide in a sliding direction, and

friction retaining means arranged to exert between the two elements an opposing force against relative movement of the two elements,

wherein the friction retaining means comprises:

a friction member mounted securely to the first element to rub against the second element via a friction surface extending parallel to the sliding direction; and

a presser member for exerting a thrust force on the friction member, urging the friction member against the second element in a direction normal to the relative movement of the elements;

wherein the retaining means comprise link means linking the friction member to the first element causing the friction member to separate from the second element during movement in either direction of the second element relative to the first element,

wherein the first element is in the form of a sleeve, and the second element is in the form of a rod having facets, each of which has pads of the friction member rubbing thereagainst, and

wherein the presser member comprises a plurality of springs extending between two adjacent pads.

2. The controlled friction device according to claim 1 , wherein the link means include at least one obstacle interposed between the first element and the friction element, being engaged in a half-cavity therein, which half-cavity presents a wall shaped to cause the friction member to move perpendicularly to the sliding direction in order to cause separation of the friction member.

3. The controlled friction device according to claim 2 , wherein the wall of the half-cavity presents two slopes, against each of which the obstacle comes to bear to separate the friction member during relative movement between the two elements, respectively in one direction or the other direction.

4. The controlled friction device according to claim 1 , wherein the friction member comprises a wedge presenting a bearing surface bearing against the first element and forming an angle relative to the friction surface.

5. The controlled friction device according to claim 1 , wherein the friction pads include circularly cylindrical beating surfaces for bearing against an inside surface of the sleeve.

6. The controlled friction device according to claim 1 , wherein the friction member comprises two bridges facing each other and urged towards each other by the presser member in order to clamp onto the second element.