Instead the locking of the webbing is standardized by the regulation R 16 and isgoverned by two independent systems: the geometric and dynamic system.
The geometric system causes the locking of the belt when, due to external events(deceleration, shock, etc.） ， the car moves by a significant number of degrees compared tothe reference horizontal position.
Load limiter
To retain vehicle occupants with safety belts without penalizing the comfort or createsecondary injuries is a relatively complex task; the load limiter represents a valuable aid toreach the goal，thanks to the use of the pretensioners，by now almost standard, which areanalyzed below.
The load limiter, nowadays practically an integral part of the retractor, has the taskof limiting the force transmitted by the belt to the shoulder and the chest during animpact，so as to mitigate any effect on the occupants. Part of the load limiter is the torsionbar，located in the retractor. During impact, it twists around, enabling a limited andcontrolled unwinding of the webbing so as to limit the force exerted on the occupant andthereby mitigating damage to the shoulder and chest.
【Seat Belt Systems】Seat belts are designed for adults and larger children. Small children must be properlyrestrained in child safety seats. A pregnant woman needs to wear a seat belt to protectherself and her unborn child.
