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  1. #21
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    Post Re: Tow balls kill

    Quote Originally Posted by PieterOos View Post
    What is unsafe here?
    It seems like smooth movements, well controlled with not a lot of strain.

    (It actually proves the opposite of what you are trying to convey?)
    Pieter its just a joke any excuse to finally get a toyota attached to the back of the paj. Normally its the paj's traction control freaking out in mud, needing a toyotas help.

    However I wont trust a towball. Not a chance.
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  3. #22
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    Default Re: Tow balls kill

    Quote Originally Posted by jonoB View Post
    No definitely not... These are the worst if you ask me.
    Care to explain? Have you ever seen one break?
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    Default Re: Tow balls kill

    Quote Originally Posted by jonoB View Post
    No definitely not... These are the worst if you ask me.

    This is a goose neck...
    Do you really believe the goose neck tow bar is not as strong as this recovery hook:
    Click image for larger version. 

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  5. #24
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    Default Re: Tow balls kill

    Quote Originally Posted by A1ex View Post
    Now i'm confused two conflicting statements between you and Johan?

    And which ones are you saying are the worst?
    I was originally referring to the conventional tow-ball that is fitted to most drawbars. The one that is tied with 2x M16 G8.8 bolts. (As per your post A1ex)
    I must confess that I have on numerous times snatched vehicles over the years in the KL-River with my old G-wagen's standard donkievoŽl. Must say it is a fixed model.

    These new fold-away hooks I cannot comment on.
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  7. #25
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    Default Re: Tow balls kill

    Thanks Johan, just out of interest do you guys use safety blankets even when snatching? I have seen some guys do and some guys don't...

    My theory is you obviously can't put it by the middle but you can put it near the end where your shackle sits.
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    Default Re: Tow balls kill

    Quote Originally Posted by JohanMaree View Post
    I was originally referring to the conventional tow-ball that is fitted to most drawbars. The one that is tied with 2x M16 G8.8 bolts. (As per your post A1ex)
    I must confess that I have on numerous times snatched vehicles .....
    Yes also did some recovery with those tow balls,. I calculated same time back the force these tow balls can take. Cant remember the figures you really have to gun it and use a tow rope, not a snatch rope, if the bumper can take it. But rather use the recovery points if you are not sure about it.
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  9. #27
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    Default Re: Tow balls kill

    Quote Originally Posted by MarcR View Post
    Is there an actual recorded incident of a tow ball that has broken off in South Africa?
    Why are we even bothering about this? It seems to be an Australian problem... and even they went to a lot of trouble, eight attempts, to get their tow ball to break.

    Doesn't look like the tow ball is the problem to me.

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  11. #28
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    Default Re: Tow balls kill

    So this subject has been flogged to death

    BTW a really good test on the towballs, It illustrates a whole lot of things

    The first thing that everyone must understand that by conducting unsafe recoveries severely increases the chance of an accident. Fatal or not.

    The whole principal here is safety. Eliminating risk.

    But the platform for safe responsible offroading has been set over the last 10 years and more just here on the forum. There is a lot of knowledgeable people here that share their knowledge, its for you to accept or reject.

    So please join me on a recovery event, yes for free my my side, and I will share all the nitty gritty with you.
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  13. #29
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    Default Re: Tow balls kill

    The towball recovery surely just one of the errors, or am I mad to use bridles both sides when recovering, whether snatch or straight pull?
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    Default Re: Tow balls kill

    Quote Originally Posted by MarcR View Post
    Why are we even bothering about this? It seems to be an Australian problem... and even they went to a lot of trouble, eight attempts, to get their tow ball to break.

    Doesn't look like the tow ball is the problem to me.
    And they had to weaken it

    Lets hope this is a good lesson for the towball police.

    A towball will never break in a recovery where you just pull. A vehicle can not generate force via the 4 wheels' traction to break a towball.

    The problem comes when you start jerking or snatching.

    To pull someone out via a towball is safe in terms of the towball but always take precautions in case the tow hitch is not properly attached or the rope fails.

    Id even maybe consider to say that a factory towball is stronger than many so called recovery points.

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  16. #31
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    Default Re: Tow balls kill

    Here is my 10c worth......

    I'm not condoning recovery with a tow ball, nor am I an expert in recoveries or tow balls in general. Please think safety first when attempting a recovery!
    I do however know a bit about fracture mechanics and materials though.
    Have a look at the tow ball below, looks exactly like the tow ball in the videos right? Have you noticed the nice big CHROME printed on the label.
    Chrome is good for making lovely shiny tow balls, however it has a serious detrimental effect on the fracture toughness of steel. A metal with low fracture toughness will snap of (have a brittle break) rather than bend. Exactly like the balls in the video. Almost no deformation just a clean break. Fracture toughness is most important when you apply a shock load to the metal......

    Have you noticed what a typical south african tow bar ball looks like?

    Notice the rough finish at the bottom and the paint? Over noticed how your tow ball rusts if the paint comes off? There is NO CHROME in this tow ball, it is made from cast steel, exactly like a bow shackle and your recovery point.
    This thing is much less likely to snap than the chrome balls in the video.
    Last edited by Jaghasie; 2019/02/04 at 07:49 AM.

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  18. #32
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    Default Re: Tow balls kill

    Post #31 has some good points. Things break in the weakest point. The way they did that video is that there is a sudden shock load. Brittle material doesn't like such. Heat treatment, hot dip galvanizing without hydrogen removal, wrong material composition, metal temperature etc. all can contribute to make material brittle.

    "Soft" material can also fail. It just fails differently.

    If the flying object is the pumper or the ball hitting person the result is the same.

    In the "do it correct" they put a pin. Diameter of it is not that great. Having wrong material or wrong technique that double shear pin will fail.

    Just spent several days looking into design calculation of pin and lugs. People think that design of these is easy - far from it. These recovery points are pin/lug designs one or the other way. They are single of double shear.

    If you like to do the design calcs: Stress Analysis Manual by Gene E. Maddux, Air Force Flight Dynamics Laboratory. You find the paper from:
    https://www.ntis.gov/
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  19. #33
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    Default Re: Tow balls kill

    Quote Originally Posted by Engel View Post
    So this subject has been flogged to death

    BTW a really good test on the towballs, It illustrates a whole lot of things

    The first thing that everyone must understand that by conducting unsafe recoveries severely increases the chance of an accident. Fatal or not.

    The whole principal here is safety. Eliminating risk.

    But the platform for safe responsible offroading has been set over the last 10 years and more just here on the forum. There is a lot of knowledgeable people here that share their knowledge, its for you to accept or reject.

    So please join me on a recovery event, yes for free my my side, and I will share all the nitty gritty with you.
    I know this has been talked about "in perpetuum" but one good thing from that video is that a lot of forum guys were under the impression that a chain, because of the links, is "dead". It has at least shown that a chain is not dead but it actually becomes another part of shrapnel.

    One thing that was missing from that video was the use of a chain without a kinetic strap (looong chain). I can only imagine that it will react no different to the kinetic strap.
    Last edited by Captainhook; 2019/02/06 at 08:27 AM.
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  20. #34
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    Default Re: Tow balls kill

    Quote Originally Posted by Jaghasie View Post
    ..........

    Have you noticed what a typical south african tow bar ball looks like?

    Notice the rough finish at the bottom and the paint? Over noticed how your tow ball rusts if the paint comes off? There is NO CHROME in this tow ball, it is made from cast steel, exactly like a bow shackle and your recovery point.
    This thing is much less likely to snap than the chrome balls in the video.
    What many do not take into consideration are the forced introduced by the off-centre force application by having the strap around the tow ball above the neutral axis of the 2 bolts below. The resultant moment can twist the whole attachment down and break something. This has happened and the whole bang shoot became airborne.

    Also, some of these tow balls come from suspect manufacturers. They might look the same, but certainly are not as strong as each other. When I researched this a decade or more ago, I did come across reports of some broken ones. Use them at your peril.


  21. #35
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    Default Re: Tow balls kill

    I totally agree with not using a tow ball as a recovery point. My choice and thats where I will leave my opinion on that.

    I do have a question though, on the current Ford Everests, would it be safe to use the existing set up but remove the tow ball and put a rated shackle on the insert ?


    If that is safe, where can I get a second insert for this purpose? Or maybe have one made up with a solid loop so no shackle is needed.
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    Last edited by mox; 2019/02/06 at 08:42 AM. Reason: Picture update

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    Default Re: Tow balls kill

    Quote Originally Posted by mox View Post
    I totally agree with not using a tow ball as a recovery point. My choice and thats where I will leave my opinion on that.

    I do have a question though, on the current Ford Everests, would it be safe to use the existing set up but remove the tow ball and put a rated shackle on the insert ?


    If that is safe, where can I get a second insert for this purpose? Or maybe have one made up with a solid loop so no shackle is needed.
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  24. #37
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    Default Re: Tow balls kill

    Quote Originally Posted by mox View Post
    i totally agree with not using a tow ball as a recovery point. my choice and thats where i will leave my opinion on that.

    I do have a question though, on the current ford everests, would it be safe to use the existing set up but remove the tow ball and put a rated shackle on the insert ?


    If that is safe, where can i get a second insert for this purpose? Or maybe have one made up with a solid loop so no shackle is needed.
    why?

  25. #38
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    Default Re: Tow balls kill

    MarcR I have seen one fail and it is scary. I have no idea of the condition it was in but on a snatch it came off with incredible speed. I would rather not take the chance myself thanks.

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  27. #39
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    Default Re: Tow balls kill

    "This is a goose neck..."

    The word goose neck has been in use as long as I can remember to describe the old type of towball, looong before the new vonkiedoŽl was developed to fit the latest vehicles.
    Imho and from experience with the "old" goose neck, it is strong and robust and is used every day to tow huge boats and caravans so it can surely be used to tow another vehicle weighing the same or less.
    The weak point of a towball/towbar/bullbar is its mounting bolts if not properly done (Ive even seen a towball welded to a towbar) which will put it in the same league as a recovery point mounted with mild steel bolts and rivnuts.
    So what Im saying is Ive seen goosenecks bend but never shear under serious forces.
    However Im sure its not designed for a proper recovery of for instance a heavily bogged down vehicle hence the warning to only use recovery points which I absolutely agree with.

    If you live each day as if it was your last, someday you'll most certainly be right. SJ

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    Default Re: Tow balls kill

    Quote Originally Posted by Jaghasie View Post
    Here is my 10c worth......

    I do however know a bit about fracture mechanics and materials though.
    Have a look at the tow ball below, looks exactly like the tow ball in the videos right? Have you noticed the nice big CHROME printed on the label.
    Chrome is good for making lovely shiny tow balls, however it has a serious detrimental effect on the fracture toughness of steel. A metal with low fracture toughness will snap of (have a brittle break) rather than bend. Exactly like the balls in the video. Almost no deformation just a clean break. Fracture toughness is most important when you apply a shock load to the metal......

    Have you noticed what a typical south african tow bar ball looks like?

    Notice the rough finish at the bottom and the paint? Over noticed how your tow ball rusts if the paint comes off? There is NO CHROME in this tow ball, it is made from cast steel, exactly like a bow shackle and your recovery point.
    This thing is much less likely to snap than the chrome balls in the video.

    Interesting point but Iím not so sure that Chromium is actually a problem, its fracture toughness and most other properties are actually better than steel (see values below). Chromium is a slightly stiffer material (by about 20%) but that specific tow ball system is so rigid that modulus of elasticity E (stiffness) is almost irrelevant. Shock loading isnít really present either, the load is applied in a relatively linear manner. A chain or normal rope would induce shock loading but then nothing survives mainly because of the massive resultant force associated with momentum.

    Will comment on tow bar failure separately a bit later.


    Fracture toughness range for Chromium = 120 to 150MPa√m
    Fracture toughness range for Stainless Steel (steel with chromium) = 112 to 278MPa√m
    Fracture toughness range for Mild (low carbon) Steel = 41 to 82MPa√m
    Fracture toughness range for High Tensile (high carbon) Steel= 27 to 92MPa√m

    Tensile strength range for Chromium = 370 to 760MPa
    Tensile strength range for Stainless Steel = 480 to 620MPa
    Tensile strength range for Mild Steel = 345 to 580MPa
    Tensile strength range for HT Steel = 550 to 1640MPa

    Shear Modulus (MOR) for Chromium = 115GPa
    Shear Modulus (MOR) for Mild Steel = 80GPa (stainless steel is similar)

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