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spring-type seat belt pre-tensioners



 
 
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  #1  
Old March 4th 19, 03:53 AM posted to rec.autos.tech
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Default spring-type seat belt pre-tensioners

Cars I have driven had explosive pre-tensioners. I learned there was also
mechanical spring pre-tensioners. Which vehicles used these?
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  #3  
Old March 13th 19, 02:05 PM posted to rec.autos.tech
Scott Dorsey
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Default spring-type seat belt pre-tensioners

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.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #5  
Old March 14th 19, 03:42 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."
  #6  
Old March 15th 19, 11:22 AM posted to rec.autos.tech
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Posts: 113
Default spring-type seat belt pre-tensioners

On Wednesday, March 13, 2019 at 10:05:35 PM UTC+8, Scott Dorsey wrote:
>
> 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.
> --scott
>

I saw them in Youtube videos (by themself not in a car).
Just wondered what vehicles used them.
Presumably they were less reliable and needed a good housing to keep
dirt out.
 




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