Pretensioner or belt tightener

摘要

An apparatus (20, 400) comprising: a gear (402) operatively linked to a rotationally supported spool (20) to rotate the spool (24) in a direction of retraction to cause a seat belt (22) wound thereabout to retract; a belt tightener comprising: a gear unit (410) having a first drive member (412) which is initially uncoupled from the gear (402) and which as it rotates is placed into driving engagement with the gear (402) and which upon further rotation is moved to a condition of disengagement with the spur gear to permit the spool to rotate free of the pretensioner and a rack (420) operably connected to the gear unit to cause same to rotate.