Why seat belts on the car pulled slowly pull it out, pull it stuck fast?

Why seat belts on the Car pulled slowly pull it out, pull it stuck fast? Pull on the seat belt stuck fast, which Is one of the most basic functions of the seat belt, the seat belt when pulled fast, skewing or sudden deceleration, the inside of the seat belt retractor locking seat belt emergency locking mechanIsm to prevent the seat belt further elongated, in order to better fixed members, play a protective role, but also to another during normal use does not affect comfort.

the seat belt locking function: when the seat belt load and duration of action beyond a predetermined level, rotational force in an emergency locking mechanIsm and the shaft ELR , leading to the torsion bar in the shaft torsional ELR locks the emergency, with the torsion bar twIsting, bending element passes through the constriction, which increases the load limits the load of the torsion bar, when the bending element contracted in the end, the end of its role, the ELR shaft only torsion bar torque.

In addition to the additional rear seat belt emergency locking (the ELR) function, as well as Automatic locking in general (ALR) function, the ALR mode Is also called fixing the child seat mode, used when installing the child seat. When the seat belt Is fully extended, can enter the ALR mode, i.e. when the total contraction of the belt, the belt Will lock to the direction of shrinkage, Will not be stretched further, when the seat belt when approaching the fully retracted, ALR mode function Is canceled, the seat belt returns to the state of normal use.

Usually five three-point seat adopt emergency locking seat belt (the ELR); the exclusive seat Automatic emergency locking seatbelt locking + (AL -ELR, be used to secure the child seat); most modern Cars further belt further having a shoulder belt pretensioner and the lap belt pretensioner, so that a collIsion among the timely tightened to eliminate the collIsion safety signal thIs gap leads to belt Is too loose, reduce the amount of forward dIsplacement of the human chest, better protect the safety of occupants.