It's Not Just the Ball at Risk

Maybe that tube in the receiver was already suffering from stress attrition before the incident.

More to the point, that shows why HR use solid shanks and not RHS material. I wonder what the maximum working load that the hitch was rated for?

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Peter, as well as the hitch rating I can only wonder what the weight of the pair of vehicles was.
The article referred to "Super Duty" which I understand is Ford's term for their oversized pickups. They probably weighed about 4t each!
Using inertia is never a good way of releasing a vehicle from a deep mud bog. By its nature, mud sucks (in more ways than one) and a slow steady pull is more effective at overcoming the vacuum factor.

An article with the full story is here.

Thankyou Allan for bringing this to our attention.
It is the graphic examples outlined here that reinforces just why one should NEVER do it.
I agree, so sad and tragic because it just should never have happened.
One has got to wonder about engineering approvals on this stuff though. The stresses on that crazy offset hitch could never have been considered acceptable, surely. As you point out, it must have already been fractured from towing and this finished it off. Normally this recovery exercise would have caused it to bend as pointed out and to break like that is an example of longer term metal fatigue.
I just had a look at the standard Toyota issue one I use. While it does not have the offset of the one in the article, it is rather light tube (maybe 4mm) welded to this stupidly heavy tongue. Does not make sense really and easy to figure where the failure point would be should it ever fail.
Bazooka made a good point about tow points to. I have often enough looked at the ones on my prado and wondered if they would take the strain of a decent load. Never considered it could potentially kill the driver of the tow vehicle though. Scarry stuff. Can always upgrade your own but it would be when you are helping some other unfortunate that you could land yourself in trouble here.
Again thanks Allan as this is helpful stuff.
Regards to all,
Roy
Toowoomba

The snapped receiver looks like it crystallised steel from excessive heat when welded imo
Have seen jobs like that before in my former career..

This may be of interest Roy:

Prado Bent Aftermarket Recovery Point

2:20 and 5:40 into video.

Shows Toyota standard tow points and aftermarket recovery points on a 150.
Pretty obviously the passenger side recovery point (alone?) has been used to recover the vehicle at some stage.

My 4x4 has a towbar that is rated to 3.5T. I bought a drop down towbar insert (~120mm drop to suit my small 7x4 trailer) and it has a label that states MAX LOAD 2127kg which is about 60% of the original.
The drop down hitch in this incident looks to be 400mm so I wonder what it was derated to?

Nickb : my guess is this is not a rated tow hitch more likely homemade or similar as per my comment above

Yep we should all know the rated limits of our equipment and what they really mean Nick, although I doubt the vast majority of us could estimate the actual weights/forces involved in a bog recovery. Towing is a completely different kettle of fish to a static pull.

Rating is irrelevant in this case. Drop down hitches especially are not suitable for recovery involving significant kinetic energy and force. The one in the story was pretty clearly placed under enormous stress, may have already had some weakness as some have surmised, but broke pretty much where you'd expect given the extreme drop on the hitch and the pivotal forces involved. Easy in hindsight and from the comfort of home.

The Robert Pepper link in my separate post below has the "full" story, explains why ddh's are generally a no no for recovery, and gives PLENTY of good guidance on techniques and do's and don'ts. Well worth a look.

The author of this article on that US accident is an excellent motoring journo, a rare breed ime :

Drop hitch failure

There was also another incident up that way in the late 90's where a young bloke was towing a tractor tyre around (common enough to grade the tracks), with a strap. The tyre snagged and the attachment ripped out of the tyre and 'shot' him in the back through the rear of the car. Got some pretty severe damage. I cannot recall the names and places precisely, but I thought it was Lorella.

Here's a better image.

Cheers
Jim

A decade ago I got stuck in the mud east of Wiluna after some unseasonal rain disrupted the government environmental project I was volunteering on.

My rescuer used a chain. Told me his department had banned snatch straps for safety reasons.

I don’t recall the chain being all that “gentle” though.

Stay safe in the floods people.

The chain is just a chain - it has no say in the matter - it just connects you to the problem ...lol

The snatch strap would be safer if used correctly, can be used over and over again and can be cut to separate the
vehicle's if you really need to. If you shock load a chain it should be thrown away for safety reasons. I wonder how his department came up with the idea chain is better using it for something it isn't designed for.

Batts The whole point of using a chain is NOT to shock load it - As originally discussed….Safety wise this is by far a safer option for 90% of recoveries

Batts, I am not sure about how many times a snatch strap can be used until all the “stretch” has been taken out of it. Most “experts do not recommend repeated snatching operations. Yes, you can use a snatch strap in a “kinetic” recovery multiple times, but I am not sure how many. Once all the stretch has gone, it is just a “tow” strap, and not a snatch strap. Also, I don’t think I would be cutting it, if it is too long, I would use a shackle and double it back to the recovery vehicle. Happy to stand corrected if I am wrong.

Macca.

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Hi Macca, I have seen "four pulls" nominated a few times but I don't know how they arrived at that. I think it was purely conjecture. The degradation of the strap would be not only the number of uses but also the severity of use, so a nominal figure is just that.... nominal. Provided that the strap rating has not been exceeded to cause filament fractures or weakened by other abuse, it should still be safe to use.

I consider that a major problem of snatch straps is that they are promoted as whizz-bang devices that will pop a stuck vehicle out with the ease of a champagne cork. So a heap of gung-ho drivers will display great prowess and apply heaps of inertia from the start without trying a gentle pull .

The real advantage (and purpose) of the straps is to allow the towing vehicle to attain some engine power and have the clutch fully engaged before the tow load is progressively applied without sudden shock. This is enhanced by some inertial energy of the tow vehicle to accelerate the towed vehicle. If much more inertia is required to dislodge the bogged vehicle then proper preparations have not been made and excessive loads are applied to both vehicles, the strap and its attachments.

So, if the strap is still achieving and absorbing the take-up shock to satisfaction, I would continue to use it. Gently.

Wearing a very similar hat I had come to the same conclusion regarding the failure - a fatigue crack situation similar to many seen in the aviation industry.

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As per my FollowupID: 921287 at the top of this page?

Definitely Allan. It didn't "just snap" out of the blue. Not a ductile failure.

"As per my FollowupID: 921287 at the top of this page?" - yes exactly - I'm supporting your view.

" Not a ductile failure." It's obviously not possible to be definitive on this, however my thought is that it appears (while not being certain) to be initiated as a brittle fracture in the lower part of the section and to propagate upwards - the photo appears to show a clean fracture structure at the lower section with little or no deformation, and some evidence of "tearing" of the metal at the upper horizontal part of the section, which indicates a final ductile failure.

Alan, as you observed (only) the final part - the upper portion of the box section - was anything like ductile. The lower part was IMO definitely brittle fracture.