Patent ID: 8740735

Claim:
A damper pulley assembly comprising a hub; a seismic mass connected to said hub to define a dynamic torsional vibration damper; a pulley connected to said hub; and elastic means for connecting said pulley in torque-transmitting mode to said hub; wherein by comprising a first one-way stop means for arresting said pulley in a first stop position with respect to said hub or said seismic mass in a first direction, when said elastic means reach a predetermined torsional load; a second one-way stop means for arresting said pulley in a second stop position with respect to said hub or said seismic mass in a second direction opposite said first direction; wherein said first one-way stop means comprise a projection carried by one of said pulley and said hub or by said seismic mass; and a first stop carried by the other of said pulley and said hub, or by said seismic mass, wherein said second one-way means comprise a second stop which cooperates selectively with said projection, and wherein said elastic means comprise a spiral member made of a material at least predominantly stressed by the torque transmitted between said hub and said pulley when said pulley is in said first stop position; adjacent turns of said spiral member being radially detached when said pulley is in said first stop position; and further comprising a first and a second shoe carried by said spiral member; and in that said second stop has a fixed angular position, so that the torque between said hub and said pulley is transmitted predominantly by said second stop when said pulley is in said second stop position such that the second stop position corresponds to a substantially unloaded condition of the spiral spring.