| 摘要 |
<p>A locking unit locks a spool (1) to a lock wheel (6) against rotation on sensing a crash, a force limiter allowing further pay-out of the seat belt webbing after the spool has locked under the influence of an occupant's forward momentum. A force limiter comprises a torsion bar (3) attached at one end to the locking wheel and at the other end to the spool. A secondary force limiting mechanism, preferably a wire (5), is releasably coupled in the force path between the spool and locking wheel, the mechanism being de-coupled after a predetermined number of turns of the torsion bar. The locking unit comprises a locking element (4) which is resiliently biased to a spool-locking position and is held out of locking engagement by the secondary force limiting mechanism.</p> |
