US Patent 9033832 Isolating decoupler

An isolating decoupler comprising a shaft, a pulley journalled to the shaft, a torsion spring engaged with the pulley, a wrap spring frictionally engageable with the shaft, the torsion spring and wrap spring connected in series such that each is torsionally loaded in a winding direction, the wrap spring comprising a variable cross-section having a first cross sectional dimension and a second cross sectional dimension, and the wrap spring temporarily releasable from the shaft in an overtorque condition by contact with the pulley urging the wrap spring in an unwinding direction.