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Old March 14th 19, 04:42 PM posted to rec.autos.tech
Scott Dorsey
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Default spring-type seat belt pre-tensioners

In article >, Steve W. > wrote:
>Scott Dorsey wrote:
>> In article >, Steve W. > wrote:
>>> wrote:
>>>> Cars I have driven had explosive pre-tensioners. I learned there was also
>>>> mechanical spring pre-tensioners. Which vehicles used these?
>>> Usually those are only in the bargain basement vehicles not sold in the US.

>>
>> The first cars I drove with seatbelts had no mechanism at all, you just
>> adjusted the shoulder belt to fit you and it didn't move in or out. People
>> hated them.
>>
>> For many years, seatbelt systems used a ratchet retractor gadget that
>> allowed the seatbelts to be pulled out slowly but they would stop if they
>> were pulled out too quickly.
>>
>> I don't know of any mechanical pretensioners, although I would not be
>> surprised if they existed in the transition period between retracting belts
>> and the modern explosive pretensioner.

>
>They are more common outside the US. Basically a simple inertial weight
>and spring with a pawl that releases and locks the belt, same basic
>design as the child seat style belts but self locking if the weights
>trigger them.


That's not pretensioning at all. That's just a locking belt, like we had
in the US throughout the eighties.

A pretensioner would need a much larger weight that actually tightens the
belt instead of just locking.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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