Seat belt retractor

摘要

A seat belt retractor has a webbing spool fixed to a ratchet wheel having a plurality of teeth spaced about its circumference. A locking pawl has a plurality of teeth with a pitch less than the pitch of the teeth on the ratchet wheel. The pawl is arranged to pivot into engagement with the ratchet wheel, on activation of a crash sensor. Preferably there are two locking pawls and two toothed ratchet wheels. The two locking pawls may each have the same number of teeth or alternatively one may have an extra tooth which serves as a sensor tooth, engaging first with the spool ratchet wheel and phasing engagement of the other teeth as the load increases.