Patent ID: 8567572

Claim:
A controlled-friction device comprising: first and second elements mounted to move relative to each other in a sliding direction, a presser member, and first and second friction members arranged symmetrically between the first and second elements in order to rub selectively against the second element, each of the first and second friction members being urged towards a wedging position by the presser member, wherein the first friction member is arranged, in a first direction of relative movement between the first and second elements along the travel direction, to tend to prevent relative movement between the first and second elements, and in a second direction to exert on the first and second elements an opposing friction force that depends on a stress applied against a first wedge member by the presser member; wherein the second friction member is arranged in the second direction to tend to prevent relative movement of the first and second elements, and in the first direction to exert on the first and second elements an opposing friction force that depends on a stress applied to a second wedge element by the presser member; and wherein the device further comprises neutralizing means for neutralizing that one of the first and second friction members that is suitable for blocking relative movement of the first and second element in one direction or the other, while leaving the other one of the first and second friction members to exert the opposing friction force.