Abstract: A buckle pretensioner for a vehicle safety restraint comprising a buckle head (1) for receiving a buckle tongue to secure safety restraint webbing about a vehicle occupant in a three-point belt system, a cable (2) connected to the buckle head (1); and means (7) for rapidly withdrawing the cable in a belt tightening direction, the withdrawing means (7) comprising a force reservoir (8), and driving means (6), and being of a compact construction through the use of step-up gearing (3, 4) to magnify linear movement produced by the force reservoir (8) which may be a pyrotechnic gas generator or a spring. The driving means (8) may be a piston-cylinder (6, 8) or a rack and pinion. The gearing may comprise a pulley arrangement (3, 4). Alternatively a roots motor or a gear pump could be used.

Abstract: A buckle pretensioner for a vehicle safety restraint comprising a buckle head (1) for receiving a buckle tongue to secure safety restraint webbing about a vehicle occupant in a three-point belt system; a cable (2) connected to the buckle head (1); and device (7) for rapidly withdrawing the cable in a belt tightening direction, the withdrawing device (7) comprising a force reservoir (8), and driving mechanism (6), and being of a compact construction through the use of set-up gearing (3,4) to magnify linear movement produced by the force reservoir (8) which may be a pyrotechnic gas generator or a spring. The driving mechanism (8) may be a piston-cylinder (6,8) or a rack and pinion. The gearing may comprise a pulley arrangement (3,4). Alternatively a roots motor or a gear pump could be used.

Abstract: Force limitation in retractors is needed to avoid injury to an occupant from the seat belt itself particularly at high crash impact loads. The invention provides a seat belt retractor comprising a spool including force limiting means for allowing further payout of the seat belt webbing after the spool has locked, under the influence of an occupant's forward momentum in the crash condition.