Towball recovery?

[Wooders]

Firstly BJ mate - didn't realise it might touch so "close to home".

I personally recommend specialist recovery points being fitted to the vehicle, but it was as AussieCJ said something that was sparked in my mind as a result of the brief conversation I had last night. I have never seen a tow-ball shear - nor do I wish too....but it seemed that many people said it shouldn't be done and yet none (that I have previously asked) had ever actually seen it occur.

I recalled an article written by 4wd monthly titled "4x4 Myths" or some such thing. and it discussed the strengths of the tow-ball and how it was often a misconceived danger. Now in my mind (non-engineer & alcohol impaired) there was a level of logic to the article.

I'm not a big fan of the tow-ball recovery because I have seen the strap slip off, especially if there is some angle in-play. In each case I've seen when the strap has slipped off it's been effective at low tension, because it seems that the strap will often sit wedged in the lower side of the ball once under load or simply slip off as the load builds – not suddenly at full load.

Also in my mind I was thinking that a snatch was a dynamic recovery - ie the like a rubber band the snatchie would stretch building up kinetic energy progressively - not shock loading the system.
As compared to using static recovery equipment - chains cables which are designed for a gradual take up of load and if used in a dynamic recovery WOULD result in a shock load.....make sense??

I explained earlier briefly about my theory regarding the pin shear resistance vs. the bending effect. So I won’t bring that up again.

Now I have no doubts that if static recovery equipment (chains/wire) was used in a dynamic recovery (ie snatching) without the correct dynamic link to absorb the energy that the shock load COULD result in a sort of catastrophic failure such as tow-ball shear…hence why I would be interested to know if anyone has seen it occur and could comment on the setup employed to determine if it was in fact other poor choices of configuration that lead to the failure.

So then I thought I’d throw the theoretical question onto here – in part expecting to get a “bloody idiot” response – but more importantly to get some ACTUAL clarification. And to try and either prove or disprove categorically the age old tale (so to speak)........

[BundyRumandCoke]

The timing must be right. At our 4wd club meeting last night, this very subject was raised, as a result of someone getting killed recently by a sheared towball (perhaps the unfortunate guy mentioned previously in this thread) QA4WDC basic driver awareness used to teach that the reciever hitch pin is acceptable. These days, they say to remove the ball, and use a rated shackle through the towball hole to connect to the snatchem. Tow ball, NO WAY!!!!!!!!!!!!!!!!!!!!!!!!! They can and do shear off. The reason i see for using the bare towbar tongue in the reciever is because, given the width of the tongue inset into the reciever, there is virtually no gap in the width. Therefore, the shear factor on the pin is greatly reduced. Naturally, the further the distance the load is placed from a fulcrum, the greater the leverage, hence the greater the chance of bending or breaking something. Given the original scenario of this thread, I would remove the towball tongue from the reciever and use the reciever pin as an anchor point. Correctly mounted recovery points fitted front and rear would negate the arguement completely.

[napsta]

i'm not saying u can use the ball, but the ball shearing stories are mostly for awhile ago when tow balls were made of two different sections, the ball and the treaded bar. thus they used to shear off at the joint, not just on snatch's, but normal towing aswell.

now they have to conform to standards and other things, and the accidents are far fewer.but from reading above, they obviouly do happen.

[oldhilux]

BJ WROTE

A good friend of mine died 30 kilometres from my house towing from the towball, on the 21st of March 2003 (less than two weeks ago) NO OLD WIVES TAILS, That is as true as I am sitting here, the ball sheared off, and tore his head in half. His Landrover Defender 130 was trapped in quicksand on the beach. He was towing with his Tractor.

I can confirm this is NO OLD WIFES TAIL it happend

Don't let it happen to you JUST DON'T DO IT



MIKE

[POS]

GREAT TOPIC WOODERS!!

This is really good and i might even mention to Ruff and Sam if we can have a dedicated "4WD Safty column" (might be some sort of legal issue though) but this should be more frequent on this board!!

I have used the TOW BALL once or twice only when there has been nothing else to use and only on VERY light pulls!

After talking to BJ the other week and hearing that horrible story i thought to myself never again!

I have heard from a couple of other people that this Gentleman was a very Experienced 4 wheeler!

I also remember reading in 4wd monthly that it was quite OK to use the Towball, I FOR ONE WON"T BE FINDING OUT!!!

In the long run when you think about it we are all out there to have fun and get home in one piece.

So take some of these suggestions to mind and next time you see someone doing the wrong thing or you go to do the wrong thing think about this topic and change the plan of attack!!!!!

Once again thanks WOODERS for bringing up such a TOPIC as it has certainly helped some of the NEWBIES out and hopfully it may have taught the odd OLD DOG a new thing or two.

[RUFF]

Ok i havent seen it personaly but i have seen it on a Video a mates father has. He was at a driver training day somewhere and they had a lifting strap(not a snatch) tied to a tree and then conected to the back of a GQ patrol via the tow ball.
Between the GQ and the tree was a bonnet with a small hole cut through it for the strap to pass through. They attached the strap and accelerated fairly hard till the strap took up on the ball. It didnt even look like it took much effort at all and sheered the tow ball off like it had been machined of in a lathe.
The ball also punched a huge hole straight through the bonnet.
I have never and would never snatch from a tow ball. I dont even like recovering from the tounge if it is not a receiver hitch style towbar as i have seen a few towbars ripped clean off the frame mainly on zooks and hilux's.

[hypo]

Now I know the stories of tow balls breaking and causing death & mayhem....But I'd like to get some facts or at least detailed theory on this.
I mean first & formost has ANYONE ACTUALLY seen a towball shearoff? No old wives tales....
Seems plenty of you will relie upon the pin (is that rated??) compared to the ball which according to ADR's SHOULD be rated.....
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well if it is a haymen reece tow bar then the pin should b strong enuf.

and i cannot uderstand how there is any more load placed on the pin than there wood b if u used the hitch with the tow ball removed...............

[RUFF]

There is more load placed on it because with the hitch fitted the load is evenly placed on both sides but with a strap it is usually placed right in the centre of the pin causing it to bend.

[taziiy]

ive been told the same thing as most of u have been saying take the ball and tongue out and use the pin in the hayman reece type bars

[landy_man]

If we go back to high school physics, some of you may remember this....

f = ma

where f is force
m is mass
and a is acceleration


do the math and you will find the force being exerted on the towball will be near it's 3500KG rating, which is for constant load

[bj on roids]

Firstly BJ mate - didn't realise it might touch so "close to home".

I am not offended, I just hope that people heed the advice, and DO NOT do it.

[bj on roids]

GREAT TOPIC WOODERS!!

This is really good and i might even mention to Ruff and Sam if we can have a dedicated "4WD Safty column" (might be some sort of legal issue though) but this should be more frequent on this board!!

I have used the TOW BALL once or twice only when there has been nothing else to use and only on VERY light pulls!

After talking to BJ the other week and hearing that horrible story i thought to myself never again!

I have heard from a couple of other people that this Gentleman was a very Experienced 4 wheeler!

I also remember reading in 4wd monthly that it was quite OK to use the Towball, I FOR ONE WON"T BE FINDING OUT!!!.

I read that article too. Interesting.

[bj on roids]

Ok my $0.02

Tow ball is designed to have a full coupling around it and a soild draw bar meaning there is a very soild connection reducing shock load

this also means the line of force is kept pretty square on to the ball

There is also downward weight on the tow ball

A strap on the ball wll only load up a very small part of the ball and will effectly pull the ball on a angle

The tow ball has a single sheer point where the bolt goes throw the tounge when you twist this it means a very small contact point increasing the sheer load. Then you had the stretch and kinetic energy of the strap and things go bang sure you may get away with it a number of times but I WILL NEVER HELP YOU RECOVER IF YOU WANT TO USE THIS METHOD

The pin has 2 sheer points either side of the hitch tube this makes it a lot harder to sheer the pin and the pin will remain square to the tube maximising the contact patch and spreading the sheer load.

The pin can bend as you are putting the load in the middle of the pin where normally the load is on the edges of the ping near the indside surface of the tube


If none of this makes sense do these 3 tests and tell me what you think

1. Wrap your hand around the other hand made as a fist then push down and pull at the same time how hard is it to bend your wrist of the hand made into a fist ??? This is a tow ball and coupling

2. make a fist then wrap a bit of string around it and pull it should be easier to bend your wrist this is a strap on a tow ball

3. get a pen and put either end behind a couple of books and put a bit of string around the pen and pull between the gap in the 2 books how hard is it to break the pen ??? This is the pin in the tube

The pin is my 2nd choice option

My number 1 option is to remove the tow ball and use the tounge or easier still is to carry something like the Warn recovery hook hitch

I was about to make the points of single and double shear yesterday but had to leave suddenly. Double shear (both sides of the pin must break off to cause a projectile) (think about this)

[BundyRumandCoke]

A couple of points of interest. On training days, we do a demo on how dangerous a flying skackle is. Attach a snatchem to a tree in the correct manner, (tree protector, rated shackles, ect). Attach another rated shackle to the other end of the snatchem. Now introduce a weak link into the system by making a loop of about 12mm poly rope. Attach this loop between the rated shackle and the recovery point of a vehicle. You can lean an old bonnet of a car against the tree above the treee protector. Now do a normal recovery type departure in the recovery vehicle. The stretch factor of the snatchem will take place. The weak link (poly rope loop) will then break, and the snatchem will recoil with shackle in tow. The damage to the bonnet will convince you of the importance of keeping well clear of a recovery operation, and how lethal this type of recovery can be if something goes wrong.
Another point of interest. A recent copy of 4wd monthly tested to destruction rated shackles. A 3.2 tonne rated shackle broke after 27.2 tonne load was placed on it. Admittadly, this was on a test bed, but still pretty impressive figure.

Cheers
David

[AussieCJ7]

.
Another point of interest. A recent copy of 4wd monthly tested to destruction rated shackles. A 3.2 tonne rated shackle broke after 27.2 tonne load was placed on it. Admittadly, this was on a test bed, but still pretty impressive figure.

Cheers
David

Do dont confuse safe working load and breaking strain !!!!!!

Safe working load just as the name implies means that it is safe to apply that amount of force time over time and you will be well with in the capacity of the shackle or any other device

Breaking point/strain will be well above the SWL value and in most cases well above 5 times more the above example shows approx 9 times How much above the SWL figure is a factor of the quality.

This does not mean you should use the smaller shackles on a big truck as they are cheaper, you should keep the load within the SWL figure but if something goes wrong on your recovery then the shackle is not going to break at that magical figure just like a fuse you do have some saftey margin

[bj on roids]

.
Another point of interest. A recent copy of 4wd monthly tested to destruction rated shackles. A 3.2 tonne rated shackle broke after 27.2 tonne load was placed on it. Admittadly, this was on a test bed, but still pretty impressive figure.

Cheers
David

Do dont confuse safe working load and breaking strain !!!!!!

Safe working load just as the name implies means that it is safe to apply that amount of force time over time and you will be well with in the capacity of the shackle or any other device

Breaking point/strain will be well above the SWL value and in most cases well above 5 times more the above example shows approx 9 times How much above the SWL figure is a factor of the quality.

This does not mean you should use the smaller shackles on a big truck as they are cheaper, you should keep the load within the SWL figure but if something goes wrong on your recovery then the shackle is not going to break at that magical figure just like a fuse you do have some saftey margin

Thanks dude, Good knowledge. Its like axles, if your axles are strong enough to cop a flogging all day from your setup then they are above the SWL your rig is putting on them, if they break sometimes, then sometimes you exceed it and sometimes you dont, exceeding the SWL dramatically wears and fatigues the product.

[BundyRumandCoke]

Agreed Aussie, It used to be, a few years ago, the SWL was a factor of about 7 of the MBL. I think, these days, it is around 6. It has been a few years since Ive had reason to play with mathematics on SWL and MBL. Suffice to say, its still an impressive figure, where as, whats the MBL of a 50mm 3500kg rated towball? And yes BJ, I agree, theres no way you should use anything smaller than a 3.2 tonne rated shackle for recovery.

[Brad]

Aus standard balls have to take around 15 tonne for a certain number of seconds!! so they SHOULDNT break in a snatch! winching would be differant!!

Try putting the strap over tounge and crossing it over the ball, that way the most force is on the younge and the ball only supports it in position!!! Used this many times, WONT BREAK, AND the strap WONT flick off!

I have found this can cause problems with the snatch strap getting cut / worn through on the sharp edge of the tongue.

[big red]

the towball is rated [ if its brand new ] at 3500kg but the further up you apply the load [ from the tongue ] the more leverage you put on it and if its in the groove its about 25 mm up from the tongue.
The pin is supported on both sides so no leverage.
And finally the towball and tongue are held in by the pin anyway so if the pin does shear off the towball and tongue are heading for the back of your head, if its only the towball that shears off its still the towball heading for the back of your head.
If you only use the pin and it shears off the worst is a 50mm wide piece of pin inside the loop of the strap is heading for the back of your head.
I'll take the safest option...the pin method
shane

[Liam]

Had this agruement a few times, theres always some idiot saying "but my tow ball is rated to more than the shackle' ...your not comparing apples to apples. The tow ball is rated for towing, the shackle is rated for snatching in a given direction. these aren't the same. If you got the testing bodies to rate a towball for snatching, the SWL they'd come up with would be very low figure.
If you want to snatch off a towball, I'll try and talk you out of it, then I'll stand back and watch ( because someone should be around to tell the cops what happened to you)

[landy_man]

shackles are NOT rated for snatching.....
they are rated for lifting

There are not ADR's for kinetic recovery i.e. snatching

That is why you will never get a guarantee from a company that their gear wont break.

[GQ Toy]

It is my understanding that an ADR compliant towball rated to 3500kg also has to take a shock load of 8000kg. Saying this I rarely use the towball alone, usually the strap is onto the ball and wrapped back around the hitch frame, as long as there are no sharp edges. This would help the shock loading as well I think.

[AussieCJ7]

Had this agruement a few times, theres always some idiot saying "but my tow ball is rated to more than the shackle' ...your not comparing apples to apples. The tow ball is rated for towing, the shackle is rated for snatching in a given direction. these aren't the same. If you got the testing bodies to rate a towball for snatching, the SWL they'd come up with would be very low figure.
If you want to snatch off a towball, I'll try and talk you out of it, then I'll stand back and watch ( because someone should be around to tell the cops what happened to you)

Also see my post with a couple of little test you can do your self to see how this will work

the key point is that the tow coupling wraps all around the ball and has downwards force aswell as a pulling force the strap does not do this

[Jonesy]

mmmm...i might as well get involed

Ive seen 3 snatch straps break... kind of... never a shackel and just a strap can do quite a bit of damage ( they go off like a rifle )

1. Stiching at the on the loop broke = Toyota Fourunner with smashed grille and radiator

2. ARB strap broke clean just below loop = another runner with 3inch dent in tail gate and broken rear window.

3.STRAP SLIPED OFF BALL = hilux with broken windscreen

[Wooders]

Jonesy,

I've also seen 4 snatches actually break - as you said they still go pow....
2 of those that broke nothing was damaged,
1 of those resulted in a smashed tail light,
1 of those resulted in a 2" dent in panel....

I've also seen one fail where it sorta when "Hmm" and didn't actually break but just became a birds nest of fibre.....

At the end of the day I believe the snatchie SHOULD be the weak link and should be the first thing to fail - even though it can still cause this sort of damage - hence we everyone should get the hell away for the recovery in the first place....

[Guy]

The few snatch recoveries I've seen go wrong, one ended up with minor panel damage .. the other ended up wit the bow shackle tearing a 6 inch cash in the rear tank of a 75 series .. that was after it hit the spring shackle and sheared the head off one of the bolts ..

[BeZeRK]

i though most of us wouldve seen the 60 series at tuff truck that the snap snapped on...

Oh, and its off topic, but how good was them tug o wars!!!!

[spazbot]

the question is do most ppl know how to tell when thier snatch needs replacing ???

there are colored strands that are woven into the snatch straps
that will become visibile when the strap has been overloaded or used way to many times, once these strands can be seen cut the strap up and toss it in the bin. Or use it for a rope swing into the river or some other smart use.

[robbie]

do all snatch straps have the coloured thread woven into them?

I thought only black rat straps had this..

[spazbot]

ARB ones def do aswell
and our old one im not sure were it came from had them cuase you can see the two dright red lines all the way down the strap