Torsion damping device, for clutch driven disc for a motor vehicle

A torsion damper device, particularly a clutch plate assembly, of the type comprising at least two coaxial parts (A,B) mounted for rotation relative to one another within the limits of a determined angular movement against the action of circumferential action elastic means (11, 111) adapted to act circumferentially between them for at least a range of the said angular movement, characterised in that torsion damper device comprises at least one locking means (15, 70, 102) which is sensitive to the angular movement between said parts (A,B) against the action of return means, said locking means being movable reversibly between a retracted waiting position in which said locking means is inoperative and gives full freedom of action to said circumferential action elastic means (11, 111) and an extended operative position in which beyond a determined angular movement between the said parts (A, B) said locking means brings about the positive circumferential support of one of said parts (A, B) on the other of said parts for at least one of the directions of rotation, and thus puts said circumferential action elastic means (11, 111) out of action for at least a part of the said movement range.