Seat belt retractor with load limiting stop mechanism

A seat belt retractor comprises a rotatable spool on which seat belt webbing is wound. The spool is rotatable in a webbing withdrawal direction and an opposite webbing retraction direction. The seat belt retractor also comprises a pretensioner actuatable to rotate the spool in the webbing retraction direction and a load-limiting system to limit a load applied to a vehicle occupant by the seat belt webbing. The load-limiting system includes a torsion bar mounted such that the torsion bar is twisted when a load in excess of a predetermined load is applied to the spool in the webbing withdrawal direction by the seat belt webbing. The bad-limiting system also includes a stop assembly actuatable to limit rotation of the spool in the webbing withdrawal direction to a predetermined number of rotations while the torsion bar is being twisted. The stop assembly is actuated upon actuation of the pretensioner.