I have used the pin method a lot on the beach,, but only for gentle tugs, except once when it was a case of get the series 3 (and trailer!)over the lip or lose it to the tide, ripped the eye stitching quite significantly but didnt bend the pin.
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I have used the pin method a lot on the beach,, but only for gentle tugs, except once when it was a case of get the series 3 (and trailer!)over the lip or lose it to the tide, ripped the eye stitching quite significantly but didnt bend the pin.
That's horrific! (turkeybrains post)
I think the lesson from this is not to use a snatch strap, at least until you have a 'proper' recovery point set up and then only at a walking pace if absolutely required.
I've used them lots in the past but over the last year or two have noticed that LR's 4wd engineer guru for the last 40 years (Roger Crathorne) says to never ever using a snatch strap, do a little pre-tow ground prep if required and do a slow tow with a non-dynamic tow strap/rope. If anything breaks then there's little energy stored in the tow strap and things pretty much fall to the ground - at least they don't shoot through the entire car!
I've come around to Roger's way of thinking and found it take a little more time but gets the job done. I do still carry a snatch strap though for those times when no one has any grip at all: in my experience that is only when both vehicles are on wet clay.
This was a couple of my mates, not me.Quote:
Originally Posted by ramblingboy42
I agree though, the weak point was the bolts which held the tow hitch on. I had a look at the nuts and bolts after the incident, and other than some serious thread damage which would have happened in the failure, there was also evidence of rust in the threads, which would have weakened them at least a little. I know I checked, but I have forgotten what they were rated. The mounting point also isn't in line with the hitch plate, further weakening the whole system by providing a lever arm. The owner of the vehicle is planning on upgrading to proper rated recovery points before using snatch straps or other recovery gear again. I don't expect he'll put a shackle through the tongue ever again!
At least everybody lived to tell the tale.
-Martin
We rabbit on about using rated equipment and quite rightly so but where tow bars are concerned we tend to over look the rating of tow bars because they are hard bolted to the car - even using a Haymen Reece type bar with a square receiver hitch the max rating of 95% of these bars is 3500kg (there are a few higher and most are less). Yet we quite happily snatch using these 3500kg rated bars with 9000kg rated snatch straps - and really in a heavily loaded vehicle, really bogged in a snatch situation there is every chance you will exceed the 3500kg of the bar and we see how often 9,000kg rated snatch straps break.
If we adhere to the rated gear philosophy we should really not be using tow bars in our snatch recovery processes.
I also agree about trying to tow before snatch - many people go straight for the snatch recovery when with a little bit of thought a simple tow may work.
Garry
Quote:
Originally Posted by garrycol
My thoughts exactly Gary, im not a fan of snatch recovery and will try the to method first everytime,
Good point Gary, but you are missing the fact that if the HR type towbar is officially "RATED" by a Government agency equipped and authourised to do so, the 3500kg rating you are talking of is the WLL or SWL of the bar. If a rated bar is 3500kg SWL then it will have a Safety Factor built in of 5 or 6, meaning that the bar has been tested and has a Guaranteed Breaking Strain (GBS) which when divided by the Safety Factor (SF) will give you the RATED load of 3500kg.
My point is that no Government authourised testing/rating authourity is going to rate anything at it's GBS.
Now I am totally against "Rating" a recovery item (snatch strap, etc.) at it's GBS like the Manufacturers/Retailers of recovery equipment do. No recovery equipment should ever be used to it's breaking strain, but it seems most 4WDrivers do it daily.
So if anyone is buying proper Rated recovery equipment, don't buy it from someone who can't tell you the SWL/WLL of the item you're buying or has knocked them up in his backyard and then advertises it as a "RATED" recovery point, as far as I know only ARB tests to destruction it's recovery point, which have been renamed as "Tow Points", so be aware of what works and what might kill you, Regards Frank.
Who knows what standard the towbars have to be rated at but it is unlikely to be rigging standards that you are so fond of. Towbars require certification to meet government standards for towbars (ADRs ???) just as bull bars are. what that criteria are I do not know.
Garry
They are not Rigging standards, they are Australian Standards (AS****) and they apply to all Rated items from Wood heaters (AS4013) to Motor vehicles.Quote:
Originally Posted by garrycol
My HR tow bar has a compliance plate showing that it complies with AS whatever the number is (can't make it out on mine) it is "Rated to Tow 4000kgs, and a towball weight of 120kgs.
If you think there is not a SF built into those figures then imagine the loads under braking when towing a 4000kg trailer, you can't tell me that those figures won't be exceded. That's why SF are included giving you a safe load that that towbar can handle, just about any item you buy will have an AS to comply with, regards Frank.
A big influence in this case is that the point of attachment from the snatchstrap is a big long lever back to the fixing point bolts. Increasing the level and direction of stress applied to those bolts.Quote:
Originally Posted by turkeybrain
Getting back to the original question, and taking on board all of the very good points made.......
I personally wouldn't be using a towbar with only 2 bolts holding it on.
If you choose to do it, make sure everything is in a very straight line so that there are no forces placed at an angle to the bar. If this happens I'd imagine that a large proportion of the stress of a snatch recovery would go to ONE bolt.(I'm not an engineer so stand to be corrected)