The belt force limiter reduces the force of the seat belt above a certain threshold and, in conjunction with belt tensioners and airbags, lessens the risk of upper body injuries being caused to front passengers. In order to achieve this, a torsion bar in the belt retractor distorts under load. The system then releases the belt at a predefined force level. This reduces the maximum shoulder belt force and occupants are intercepted more gently by belt and airbag.
