Vent Something about the minimum weight of the seat belt being met?

treqi · Aug 24, 2012

So school just started and my friends and I carpool. Today the other "pick-up" mom and I were getting into our cars and I noticed there was no seat for the other girl and only a rearfacing Marathon I asked if she had the booster and it turns out I had left it in another familys car on Monday. I told her I wasn't ok with the girl riding in between the Frontier and the Marathon with just the belt and wasn't going to let that happen so the other mom flipped the Marathon and that was that. When I called the girls mother concerned, she told me that she was ok with it

and that her daughter had ridden before without a booster :thumbsdown: and it was "safe" because her daughter is ~52lbs and that is within the minimum weight for just a seat belt. I have never heard of such a thing? I thought once a child is in a booster it's not really a weight matter but mostly a height for proper belt positioning. Now this girl is 5 and turns 6 soon, and while she is big for her age she's nowhere near 4'9" (I'd guess max 48" maybe 50" if my kid is taller than I think for comparison). Am I just being a crazy carseat nazi? I would have been willing to stay with the kid and install the carseats but I def wasn't ok with a lil girl riding for about 10min (maybe a bit less) at speeds of 20-45mph without a seat. So is there any info about this seat belt minimum weight I can only find booster stuff when I Google and this girls mom is training to be an EMT and she mentioned that when she was referencing the weight being ok with a belt so maybe an EMT could shed some more light on the situation?

ketchupqueen · Aug 24, 2012

Well, it's true that seat belts have a minimum weight under which they're not likely to lock in a collision. However, it's also true that belt FIT is just as important- and if it locks but doesn't fit right, the child is at risk for submarining, seatbelt syndrome, partial ejection, spinal injuries, and other injuries because the belt cannot optimally protect someone who is not wearing it positioned correctly across the strong hip and shoulder bones rather than over the soft belly.

The minimum weight is usually referenced here more as a concern that the belt will function properly for booster riders. Because, well, children who don't fit the belt need a booster, until they pass the 5-step test, period.

treqi · Aug 24, 2012

OOOOOHHHHHH so thats like 30lbs? I assume this since Cosco prints that as the min weight on their boosters and I assume they'd at least have to follow that guideline?

safeinthecar · Aug 24, 2012

ketchupqueen said:
Well, it's true that seat belts have a minimum weight under which they're not likely to lock in a collision. However, it's also true that belt FIT is just as important- and if it locks but doesn't fit right, the child is at risk for submarining, seatbelt syndrome, partial ejection, spinal injuries, and other injuries because the belt cannot optimally protect someone who is not wearing it positioned correctly across the strong hip and shoulder bones rather than over the soft belly.

The minimum weight is usually referenced here more as a concern that the belt will function properly for booster riders. Because, well, children who don't fit the belt need a booster, until they pass the 5-step test, period.

This actually isn't the case. It's kinda on the path, but not quite. The seat belt retractor has a pendulum that swings with a sudden change in direction and locks the pawls in place. This happens through inertia and is not affected by weight at all. Now, there needs to be weight or tension on the belt to keep it locked in place or the pendulum will rebound and unlock the belt again, but the belt will be locked initially.

ketchupqueen · Aug 24, 2012

Then why do some vehicle manufacturers state that the belt is not intended for use with passengers under a certain weight and may not function properly in a crash? I'm guessing because they won't hit it hard enough in many collisions to cause the locking mechanism to function because of their lower weight?

_juune · Aug 24, 2012

ketchupqueen said:
Then why do some vehicle manufacturers state that the belt is not intended for use with passengers under a certain weight and may not function properly in a crash? I'm guessing because they won't hit it hard enough in many collisions to cause the locking mechanism to function because of their lower weight?

This is actually interesting. Might it be that it's simply a way for vehicle manufacturers to impress on people the need for child restraints? Ok, this is not ARL belts, bet if we look at Europe -- we have ERL belts, and, say, a bucket seat can weight as little as 3-4 kg [bases are not popular where I live] and a newborn around 3 kg. Correct me if I'm wrong -- lockoffs are there to position the seat before crash, right? To hold it in place before seatbelts lock? Then saying that a seatbelt might not lock on a 15kg child is as good as saying it won't lock on a 3 kg baby in a 3 kg bucket seat? Am I getting something really wrong, or are ERL belts just very different? Sorry for offtopick

This has been bugging me for a while.

treqi · Aug 24, 2012

_juune said:
Correct me if I'm wrong -- lockoffs are there to position the seat before crash, right? To hold it in place before seatbelts lock? Then saying that a seatbelt might not lock on a 15kg child is as good as saying it won't lock on a 3 kg baby in a 3 kg bucket seat? Am I getting something really wrong, or are ERL belts just very different? Sorry for offtopick This has been bugging me for a while.

Well technically you should have your 5-pt harness seat locked all the time either with a locking clip or pulling out the seat belt until it auto locks but with boosters it seems that either the car or booster prohibits locking or there is no guideline and locking the belt can be used for training a child in a booster... but that is only 1 hour of research I'm super new to boosters

ketchupqueen · Aug 24, 2012

No, that's true and I guess I never questioned the manuals. I think it's what SITC says- they may not STAY locked, which is kind of different. A locking clip doesn't lock the belt, it holds it in place until the belt can lock, too. It may also have to do with the different shape of a small child's body vs. a car seat belt path vs. an adult belt path?

treqi · Aug 24, 2012

ketchupqueen said:
A locking clip doesn't lock the belt, it holds it in place until the belt can lock, too.

The locking clip should lock the lap portion into place permanently though and the 5-pt seat should not move regardless of if the belt ever locks, thats the point of them is to keep seat belts that don't have the child-seat ARL "click" feature in place all the time.

ketchupqueen · Aug 24, 2012

A locking clip is a pre-crash positioner. It does not lock the belt permanently into place, it holds for the split second it should take the ELR to kick in. (It could, potentially, come off, break, bend in a crash; that would be ok. It would have done its job already. It should also be checked periodically to make sure it hasn't slid out of place.) A booster seat positions the belt properly pre-crash too. An adult needs neither because the belt should fit properly to be positioned correctly pre-crash as well. None of those locks the belt- only an ALR belt actually locks the belt pre-crash.

treqi · Aug 24, 2012

These really break?

I don't see how that's possible?

ketchupqueen · Aug 24, 2012

I doubt they would usually break. In a severe crash, at the right angle, one of the tines might. They could definitely bend under crash forces, though, deform, allow the belt to come out. They're not intended to hold all the way through a severe crash. Not saying they COULDN'T but they don't NEED to anyway, so it's not a big deal if they don't.

_juune · Aug 24, 2012

treqi said:
These really break? I don't see how that's possible?

Might this be an answer to your question? If I'm getting it right the BSC is the one clip indeed meant to hold seatbelt locked on it's own?

Euro seats are somewhat different. As pretty much all cars here have ERL belts, car-seats have built in lock-offs. The one's I've used [not that many] had just big plastic clips. Like here on Concord Ultimax "base" part -- blue lockoff for RF and red lockoff for FF, and here the big blue clip on the backside of a Jane Strata. But that's just whole lot more offtopick

sorry

ketchupqueen said:
It may also have to do with the different shape of a small child's body vs. a car seat belt path vs. an adult belt path?

I thought something like that, too. That the shape of what's held by the belt is also important?

ketchupqueen · Aug 24, 2012

Yeah. Belt shortening clips are larger, stronger, and used differently (not just pinching the belt together in two pieces) and are designed to hold the belt at a certain length differently so that they basically lock the belt by pulling it all the way out, so it only IS at that certain length to hold the car seat tight- all the slack is removed so the retractor becomes kind of irrelevant. Like why lap-only belts with locking latchplates or LATCH belts don't need a retractor- they're designed to stay at one particular length once shortened, so that they hold the seat permanently in that position with the belt at that one length. A locking clip doesn't do the same job the same way.

treqi · Aug 24, 2012

I guess I never realized there was a difference as I've used both and just thought one was a "cheaper" version

ketchupqueen · Aug 24, 2012

To be clear, a BSC may be used as a locking clip but might still come off in a crash.

spokaneCPST · Aug 24, 2012

In our teaching kit, we have a locking clip that went through a severe crash. All of the tines are totally bent out of shape and there is no way to put it on a seatbelt anymore because it is so deformed. It deformed and came off in the crash sequence.

ketchupqueen · Aug 24, 2012

I've seen pictures of that but never seen it in person.

Avery'sMama · Aug 24, 2012

treqi said:
I guess I never realized there was a difference as I've used both and just thought one was a "cheaper" version

There is no way to know which is a belt shortening clip unless you take it out of a package marked as such. I have locking clips that look identical to the belt shortening clips in weight/size and other locking clips that are thinner and a gold-ish color.

While you can use a belt shortening clip as a locking clip, you CAN NOT use a locking clip as a belt shortening clip. Belt shortening clips go on the opposite side, and serve a different purpose than locking clips.

Also, just a note that just because a seat belt doesn't switch into locked mode you do not *need* a locking clip. Many cars have locking latch plates which serve the purpose of locking the belt. I see even techs (coming in for sign offs) make the mistake of check to see if a belt locks, and if it doesn't using a locking clip, when the vast majority of the time that is not true.

Brianna · Aug 24, 2012

This is the visual difference http://www.car-seat.org/showpost.php?p=489632&postcount=26 but I would never attempt to identify a belt shortening clip as such just from looking at it- I would be absolutely sure I had ordered a BSC and took it right out of the package.

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