A double-safety emergency locking belt retractor for vehicle safety belt systems comprises an improved automatic-locking mechanism in which an axially movable latch disc locks the reel to the retractor frame upon rotation of the reel relative to an inertia wheel in the belt-unwinding direction. Such relative motion occurs when an inertia-sensitive device stops rotation of the inertia wheel in response to acceleration of the vehicle at from about 0.3 g to about 0.7 g or the inertia of the wheel causes it to lag the reel when the belt is accelerated at about 0.7 g or higher. The latch and inertia wheel are cammed axially apart upon such relative rotation, the inertia wheel being locked to a cover for certainty of cam function and the latch disc thereupon being locked to the frame.
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