Man killed - recovery - Page 5




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  1. #81
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    Default Re: Man killed - recovery

    Quote Originally Posted by Engel View Post
    Standard electrodes that most people use in their backyards are not as strong as co2.
    Ok, but low strength is the opposite of brittle, especially when it comes to welding.

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    Default Re: Man killed - recovery

    Quote Originally Posted by Engel View Post
    The guys use arc welding and if not treated can be brittle. I use co2 on welds, proper welding prepared with about 4 runs. Then bolts if I can. But I can promise you that you will tear the steel off and not break the bolts.
    The type I referred too are factory tow points which snap off.

    My rear points are welded on but they aren't coming off :-)
    Neil

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    Default Re: Man killed - recovery

    Quote Originally Posted by Engel View Post
    probably the single most dangerous product in recovery ever.
    Because it only have one hole for a bolt instead of two? And it looks thin.

    Please explain, I need to be educated.
    1993 Samurai. 2004 Jeep TJ Sport. V8 Lexus VVTi.

  4. #84
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    Default Re: Man killed - recovery

    Quote Originally Posted by Chris Stoffel View Post
    Because it only have one hole for a bolt instead of two? And it looks thin.

    Please explain, I need to be educated.
    +1
    Like Chris, I dislike these sort of unsupported statements. That is why I asked my question about failure mode of factory tie-down points.


  5. #85
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    Default Re: Man killed - recovery

    Quote Originally Posted by Chris Stoffel View Post
    Because it only have one hole for a bolt instead of two? And it looks thin.

    Please explain, I need to be educated.
    Its the same reasoning why a soft shackle is better, no weight flying around. A towbar is not designed to be recovered from. The forces and stresses far exceed the manufacturer's limitations. The the towbar fail, then tears open and you have a 4kg block of steel doing 300km/h. Also if someone throw the pin away, and replace it with a mild steel pin, you have no indication on the shear force limits. To me a big nono, and thats why oom.

    Quote Originally Posted by RodS View Post
    +1
    Like Chris, I dislike these sort of unsupported statements. That is why I asked my question about failure mode of factory tie-down points.

    Because stuff like this has been discussed for the last 10 years on the forum. At recovery training I will explain it to those that come ....wait for it....MAHALA, free, nada, Nothing niks.
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  6. #86
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    Default Re: Man killed - recovery

    Quote Originally Posted by Engel View Post
    A towbar is not designed to be recovered from. The forces and stresses far exceed the manufacturer's limitations. The the towbar fail, then tears open....
    Hi Engel

    I'm interested in this part. What are the actual forces involved in a recovery? Numerically? Anyone have an idea?

    For instance AS4177 requires that the tow bar is capable of holding full tow rating of the vehicle in the direction of tow without any plastic deformation. So the typical ute has a tow rating 3500kg, which means that to be compliant with AS4177 the manufacturer has to have proven that the towbar can withstand 3.5t without anything bending. Typical mild steel has a UTS of about two times yield, so I'd expect you could pull 7t+ before bits start flying off.

    That's a significant amount of force, is it enough?

  7. #87
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    Default Re: Man killed - recovery

    Quote Originally Posted by BruceB View Post
    Hi Engel

    I'm interested in this part. What are the actual forces involved in a recovery? Numerically? Anyone have an idea?

    For instance AS4177 requires that the tow bar is capable of holding full tow rating of the vehicle in the direction of tow without any plastic deformation. So the typical ute has a tow rating 3500kg, which means that to be compliant with AS4177 the manufacturer has to have proven that the towbar can withstand 3.5t without anything bending. Typical mild steel has a UTS of about two times yield, so I'd expect you could pull 7t+ before bits start flying off.

    That's a significant amount of force, is it enough?
    Look at this, I think I copied it from the forum.
    Attached Images Attached Images  
    Last edited by Chris Stoffel; 5 Days Ago at 06:49 AM.
    1993 Samurai. 2004 Jeep TJ Sport. V8 Lexus VVTi.

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    Default Re: Man killed - recovery

    And this.
    Attached Images Attached Images  
    1993 Samurai. 2004 Jeep TJ Sport. V8 Lexus VVTi.

  9. #89
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    Default Re: Man killed - recovery

    Quote Originally Posted by BruceB View Post
    with AS4177 the manufacturer has to have proven that the towbar can withstand 3.5t without anything bending. Typical mild steel has a UTS of about two times yield, so I'd expect you could pull 7t+ before bits start flying off.

    That's a significant amount of force, is it enough?
    Your recovery strap is rated at 8t & your rated 4.75 shackle will realistically withstand over 30t, so the attachment point becomes by far the weakest point.
    Neil

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  11. #90
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    Default Re: Man killed - recovery

    Quote Originally Posted by BruceB View Post
    Hi Engel

    I'm interested in this part. What are the actual forces involved in a recovery? Numerically? Anyone have an idea?

    For instance AS4177 requires that the tow bar is capable of holding full tow rating of the vehicle in the direction of tow without any plastic deformation. So the typical ute has a tow rating 3500kg, which means that to be compliant with AS4177 the manufacturer has to have proven that the towbar can withstand 3.5t without anything bending. Typical mild steel has a UTS of about two times yield, so I'd expect you could pull 7t+ before bits start flying off.

    That's a significant amount of force, is it enough?
    I am preparing for training, but like Neil said, forces are much more than what it's designed for, and attachment points must be the strongest. People break 12t ropes, so you need much stronger points. But I will explain it all on training
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  13. #91
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    Default Re: Man killed - recovery

    Quote Originally Posted by XJ Junkie View Post
    Your recovery strap is rated at 8t & your rated 4.75 shackle will realistically withstand over 30t, so the attachment point becomes by far the weakest point.
    So you're looking for a pad eye, that's what's it's called in oil and gas, with a +30t ultimate force? On the 2mm plate of your average car body? Sure too easy.

    If that strap snaps at 8t, that's pretty similar to the towbar, too close for comfort. These things are everywhere in Qld. I'm curious how something like this keeps on the market in a country as litigious as Australia.

  14. #92
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    Default Re: Man killed - recovery

    Quote Originally Posted by XJ Junkie View Post
    Your recovery strap is rated at 8t & your rated 4.75 shackle will realistically withstand over 30t, so the attachment point becomes by far the weakest point.
    So you're looking for a pad eye, that's what's it's called in oil and gas, with a +30t ultimate force? On the 2mm plate of your average car body? Sure too easy.

    If that strap snaps at 8t, that's pretty similar to the towbar, too close for comfort. These things are everywhere in Qld. I'm curious how something like this keeps on the market in a country as litigious as Australia.

  15. #93
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    Default Re: Man killed - recovery

    Quote Originally Posted by Chris Stoffel View Post
    And this.
    Quite an easy chart that is totally useless and you cannot determine the friction /resistance, rolling resistance and probably don't know the weight either.

    Dont make it difficult, make it easy.
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  16. #94
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    Default Re: Man killed - recovery

    Quote Originally Posted by Chris Stoffel View Post
    And this.
    Quite an easy chart that is totally useless and you cannot determine the friction /resistance, rolling resistance and probably don't know the weight either.

    Dont make it difficult, make it easy. You will have a quick understanding once you start recovering a lot.
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