Correct use of shackles - Chapter 2

Submitted: Saturday, Feb 28, 2015 at 16:31
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About twelve months ago I posted about the use of shackles in vehicle recoveries. It was at thread 101049
http://www.exploroz.com/Forum/Topic/101049/Correct_use_of_shackles.aspx?ky=shackles&sn=&p=%2fForum%2fDefault.aspx%3fs%3d1%26ky%3dshackles%26pn%3d1
I now know more about this subject so I though I would update my post.
In vehicle recoveries there are no Standards with the exception of the snatch strap. We all learn that if we use a shackle then it must be a rated shackle. The only rated shackles are those used in the lifting industry which is what we as four wheel drivers use by default.
In the lifting industry it is a no no to attach a strap to a shackle at the pin. The requirement is to have the strap in the bow and the pin in the attachment point. ARB (and others) make vehicle recovery points with slots and the instructions for use say that the bow goes into the recovery point and the strap is attached at the pin. This is the opposite to the lifting industry and some people are arguing that ARB are incorrect. ARB are correct IMHO and this is why. The Standards of the lifting industry do not apply to vehicle recovery as the equipment, forces, and risks are different, and to do so is inappropriate and potentially dangerous. In lifting you are dealing with static loads, known angles, and equipment that has been rated for the purpose. In vehicle recovery you are dealing with loads that are hard to even estimate, with angles that can vary during use, with equipment most of which is not rated for purpose, forces that are also hard to estimate, and shock loads as opposed to static loads. ARB have designed their vehicle recovery points and tested them to give the safest possible recovery, and real world testing has shown that the shackle through the recovery point and the strap attached by the pin is the safest. When you think about it it does make sense. In the lifting industry the Standards for a shackle is a tonne rating and stamped on the shackle. This rating is on the basis of a straight pull, and if you are lifting using a shackle where there is any side force another Standard says you must downgrade the shackles rating by a factor that varies with the angle of the side force. By putting the bow into the recovery point and the strap onto the pin there is no side force on the shackle as in turns with the angle of the pull so that the shackle is always at its maximum strength, and arguably its safest.
Not all recovery points have slots, the most notable is the shackle on a tow bar receiver which you replace your towball tongue with at a vehicles rear. This means that you have no choice but to have the strap in the bow and the pin in the recovery point. This is not usually much of problem as the shackle rating is to a lifting standard where the rating is about one seventh of its actual breaking point. What the user should keep in mind is that any side pull on a shackle reduces it strength and that if they are doing a difficult recovery where the forces are significant to take this fact into consideration.
I am not sure why in the lifting industry attaching a strap to a bow shackle pin is a no no, but given that many of the Standards came about as a result of a Coroner's recommendation someone probably died along the way. Most people involved in a vehicle recovery suggest when that using a shackle that you do the pin up finger tight and then back it off about a quarter turn. This suggests that the pin undoing itself in vehicle recoveries is not seen as a issue. I personally always tighten the pin by hand as tight as I can as extra insurance against the pin becoming loose. This means that sometimes I have to get a tool of some sort to undo the pin, but for me you cannot be too safe.
Every vehicle recovery is different as there are just so many variables. We are all aware that it is dangerous and a number of people have been killed during vehicle recoveries gone wrong. As I said at the start there are no vehicle recovery standards so we all can have varying opinions a to what are the correct methods. The purpose of this post is point out some issues for you to consider so that hopefully you are better informed to make your next recovery as safe as possible.
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Reply By: Peter_n_Margaret - Saturday, Feb 28, 2015 at 17:53

Saturday, Feb 28, 2015 at 17:53
I carry shackles, but prefer to avoid using them at all, if I can.

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Peter
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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 08:47

Sunday, Mar 01, 2015 at 08:47
Agree. Shackles are probably the strongest part in any recovery but of all the people killed in a recovery gone wrong I believe the majority where hit by a flying shackle.
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Follow Up By: Roachie.kadina.sa.au - Sunday, Mar 01, 2015 at 09:39

Sunday, Mar 01, 2015 at 09:39
Peter,

I'm just in the process of sorting out my recovery equipment for my "new" (to me) Silverado.

Given that this rig is probably about the same weight (GVM 4490.....and already VERY close to that figure) I am curious as to what size/rating shackles you carry?

I have always carried 4.25T shackles for my Patrols/Landcruiser, and was wondering whether 6.25T or the 8.5T size would be best? Same goes for snatch straps and equalising straps?

As for the actual use of shackles in the first instance.....with my current and last few vehicles, there really isn't a choice, as the recovery "hooks" (a misnomer really, as they are more correctly "loops") preclude the idea of just slipping the eye of a strap over a hook. As such, a snatch strap (or any other type of strap) MUST be secured to the vehicle with a shackle. The Silverado has enormous recovery "loops" (factory fit) on both sides at the front and the fear is always going to be that the system of attaching those recovery points to the chassis might not be up to the task. IE: we attach the strap to the shackle then to the recovery loop....now we have 2 hefty items that could become potential missiles IF the bolts that hold the recovery loops to the chassis, or the chassis steel itself, should happen to fail!! I have no doubts about the integrity of either the shackle/s and/or the recovery loop....it is that attachment to the chassis that bothers me the most as THAT is the unknown quantity.

Roachie



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Follow Up By: Member - Scott M (NSW) - Sunday, Mar 01, 2015 at 11:08

Sunday, Mar 01, 2015 at 11:08
Roachie, these are the hooks I have on the front of the vehicle - hopefully noy much chance if them letting go.



back set up is fairly standard and I don't think the shackle will let go in a hurry...

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Follow Up By: Slow one - Sunday, Mar 01, 2015 at 11:43

Sunday, Mar 01, 2015 at 11:43
Roachie,

Max WWL of the shackle is exactly that when lifting, you can lift that weight all day and the next until the cows come home as long as there is no damage of wear on the shackle and the same pin is used that came with that shackle.

When used for towing (and it should never be used for lifting again) that same shackle will break about 6 times the wwl, so your 4.25t will break at around 24 tonnes. I have never had a shackle let go, but I have stretched them and then thrown them away. This will occur well before they break.

You can get a special shackle called a web sling saver that limits the eye of the sling from bunching.

Thing with using them for towing is not to let the pin be allowed to come into tension or let the eye of the soft sling or snatch strap become bunched or pinched. Most accidents happen with shackles when two straps are joined and the eye or strap itself snaps and the shackle becomes a missile propelled hopefully not at someone.

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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 17:46

Sunday, Mar 01, 2015 at 17:46
Joining any straps together with a shackle is a BIG no no, far to dangerous. Thread one through the other and put a rolled up magazine or equivalent, in the join to make it easier to undo.
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Follow Up By: Slow one - Sunday, Mar 01, 2015 at 20:26

Sunday, Mar 01, 2015 at 20:26
Yes Chris it is very dangerous, what I was trying to say is, it is virtually always the attachment that fails and not the shackle, whether it is an eye, hook or attachment bolts. The only failure I have ever encountered is when the pin has been placed in tension from pulling on the side of the shackle.



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Follow Up By: Louwai - Monday, Mar 02, 2015 at 14:16

Monday, Mar 02, 2015 at 14:16
Idler Chris,
Doing what you suggest in threading the eye of 1 strap through the other & then putting something through to stop it pulling back is actually weakening the eye of both straps.

Straps (and the eye's) are designed for a straight pull. If you bend the eye as you describe you are effectively changing the "Load" point away from the intended position & moving it up along the body of the eye. Also with what you describe, you would be putting the load onto the side of at least one of the strap eye's.

If I found myself in a situation where I had to join 2 straps, I would join them with a (correctly rated) shackle & put the load on a straight pull, rather than what you suggest.
But I would not join 2 straps to use them in a snatch scenario only for a long distance slow pull recovery.


Having said that,
I have not seen mentioned anywhere about "Shock Load"....
A 2t vehicle recovering another 2t vehicle by way of Snatch-Strap would be putting far greater load onto the recovery gear than the weight of the vehicles.

Snatch-straps are designed to stretch & absorb the shockload, but there is still a considerable amount of load over & above the weight of the vehicles applied to recovery gear.
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Follow Up By: Roachie.kadina.sa.au - Monday, Mar 02, 2015 at 15:26

Monday, Mar 02, 2015 at 15:26
G'day Louwai,

I'm going to argue the toss about whether what you say is right or wrong (ie: about not wanting to join 2 straps by using a rolled-up magazine or similar through the eye of one strap etc.

However, what I WILL say is that through all the training I have done with 4WD clubs, it has ALWAYS been made clear to everybody that shackles should NEVER be used to join 2 straps together and that the magazine method (or a short length of hardwood, such as a piece of shovel handle) is the preferred method.

Based on what you've said, I gather you'd be totally against the method shown in the pic (below) where the strap is "bent" around the steel bar which is attached to the towbar of the Nissan? I thought that was a great idea.

Roachie
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Follow Up By: Roachie.kadina.sa.au - Monday, Mar 02, 2015 at 15:27

Monday, Mar 02, 2015 at 15:27
Whoops.... First sentence should have read : "I'm NOT going to argue the toss about whether what you say is right or wrong (ie: about not wanting to join 2 straps by using a rolled-up magazine or similar through the eye of one strap etc."

Sorry...

Roachie
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Follow Up By: Idler Chris - Vic - Monday, Mar 02, 2015 at 16:05

Monday, Mar 02, 2015 at 16:05
Louwai, I do not know if you are trying to stir the pot or not but anyone who suggests joining any straps with a shackle cannot be taken seriously. A number of things you say simply do not make sense. I cannot be bothered listing and explaining them all, I think others can work them out.
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Follow Up By: Louwai - Monday, Mar 02, 2015 at 23:29

Monday, Mar 02, 2015 at 23:29
Hi Roachie,
My comments are based on the basics of what a strap / nylon sling and shackles are designed for.
Looking at some of the comments I can see that Batts has experience in construction & Rigging, as I'm sure several others on here have also.


All straps which have an eye at the end are designed for a direct-pull.
If you alter the connection method of said strap / sling you reduce the WLL proportionately.
Several comments have been made throughout this thread that are misleading.

Some comments being made here assume that the strap is still capable of 100% of it's "rated" capacity when attached in a way other than a direct pull through the eye. Any attachment method other than a direct pull will proportionately reduce the WLL of the strap.


A comment was made that stated using a bridle to utilise 2 recovery points will reduce the load on each by 50%. That's not quite correct.
1) The load is only halved on each if the pull point is exactly in the middle & directly in front pulling directly forward.
Any pull position / direction other than that would load 1 point more than the other.
2) Factory recovery points on any vehicle are designed for a straight forward direct pull. When you use a bridle straight away you are putting side-loading onto the recovery point. Therefore it's "assumed capability" is reduced. And in the case of a non-central pull, this additional side loading onto 1 of the 2 recovery points could possibly be the beginnings of a failure.

I'm probably heading down the same path as your comments regarding the tow hitch mounts etc.

Cheers,

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Reply By: Member - mike g2 - Saturday, Feb 28, 2015 at 18:10

Saturday, Feb 28, 2015 at 18:10
Hi Chris, useful article. Agree, rules for rigging different to recovery.
As a FYI, in abseiling there are static and dynamic ( sretchy)ropes with different uses. recovery straps are dynamic.
Using other methods first if stuck also an idea. ( lower pressure, lowest gear, slow to-fro move....etc.)
Here are some vehicle recovery 'standards' I know of without trying to tell the whole story of how to do a recovery or teaching grandma to suck eggs!- for recovery straps the Minimum breaking strength(MBS) should between 2x to 3x the vehicle gross mass(GVM) , rated recovery points correctly att ( HT bolts to chassis rail or similar) to vehicle specific rated RP or TDP is essential. commercially available straps generally rate at 8,000 kg ( Maxtracs) and have a stretch of about 20%
The snatch strap must suit the lighter of the 2 vehicle's GVM's
a wet strap has reduced strength and stretch and use of a 'damper' on centre of strap recommended.
2 point attachment using triangulated strap is better to reduce excess stress )on the 1 side), but used of a single point -such as a centrally located rear tow hitch with a recovery device att should be ok-
use of pulley systems can increase pull power and can enable a pull from a vehicle not directly located at front or rear. (beware tie down points and obviously DONT use the ball).
as we all know-hand crank HD pullers or electric winches can be used instead of a vehicle and strap.
and so on....
a course is highly useful in managing the whole process of recovery and 4wd in general and there is a lot of general industry info in this regard. Note: RTO 4x4 courses are to a Nat recognised standard.
Is a shackle is needed ? as the loop at ea end of strap can go straight on to hook of RP.

MG.
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Reply By: Michael ( Moss Vale NSW) - Saturday, Feb 28, 2015 at 19:50

Saturday, Feb 28, 2015 at 19:50
What about this!! Michael
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Follow Up By: Idler Chris - Vic - Saturday, Feb 28, 2015 at 20:17

Saturday, Feb 28, 2015 at 20:17
Looks from the photo strong enough to me.
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Follow Up By: Michael ( Moss Vale NSW) - Saturday, Feb 28, 2015 at 20:54

Saturday, Feb 28, 2015 at 20:54
Very simple design Chris, Much of the weight is taken on the 6mm wall tube and so easy to slip on if say the vehicle is stuck in a river or the like. Uses the standard pin and is probably only 20% of the weight of the solid steel unit with a shackle on the end. Michael
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Follow Up By: Michael ( Moss Vale NSW) - Saturday, Feb 28, 2015 at 20:55

Saturday, Feb 28, 2015 at 20:55
The bar is 20mm solid black steel. Michael
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Follow Up By: Idler Chris - Vic - Saturday, Feb 28, 2015 at 21:53

Saturday, Feb 28, 2015 at 21:53
That looks cool. Anything that does away with the shackle has to be good.
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Follow Up By: Roachie.kadina.sa.au - Sunday, Mar 01, 2015 at 09:49

Sunday, Mar 01, 2015 at 09:49
Strewth!!! I just finished typing a long-winded explanation/question (above) regarding the attachment of a strap to my rig/s which have "loops" rather than hooks and emphasising that shackles MUST be used to attach a strap.

Now that picture tells a good story. Whilst that system wouldn't work on the front of my Landcruiser (which has aftermarket bolt-on recovery loops whereby the hole is only really big enough for the pin of a 4.25T shackle), I think the idea would possibly work on my Silverado. This new vehicle has very large loops on each chassis rail (at the front) and it might be possible to push the end of a strap through the loop and then pass a foot-long piece of solid steel bar through the loop to hold it in place....thus negating the need for a shackle. Hmmm...got me thinking!!!

Great idea Michael!!
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Follow Up By: Dion - Sunday, Mar 01, 2015 at 11:25

Sunday, Mar 01, 2015 at 11:25
Before using a bit of solid steel bar Roachie, try using a wooden sledge or blocksplitter handle, cut to 1' long. These wooden handles actually have good sheer strength.
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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 17:37

Sunday, Mar 01, 2015 at 17:37
Roachie I agree with slowone your 4.25t shackles should be fine. Having a very heavy vehicle requires very careful consideration of the safety issues. Suggest you check with the likes of ARB as to the safest snatch strap for your vehicle you may need an 11,000 lb strap. With your weight I would strongly suggest that you use a bridle at the front which halves the load on each recovery point. Not using a shackle at all and putting the eye of the strap through your recovery loop and securing it with a wooden stick is a really great idea. The use of a bridle at the back should also be considered given your vehicles weight.
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Follow Up By: Roachie.kadina.sa.au - Monday, Mar 02, 2015 at 15:28

Monday, Mar 02, 2015 at 15:28
Thanks Chris.
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Follow Up By: Idler Chris - Vic - Monday, Mar 02, 2015 at 16:19

Monday, Mar 02, 2015 at 16:19
Michael, The more I think about your idea and the more posts I read here the more I like your solution. It is just so superior to using a shackle it is not funny. Old way, small contact area with the shackle and a 180 degree turn, your way two lengths of the strap in contact and only a 90 degree turn.
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Follow Up By: Michael ( Moss Vale NSW) - Monday, Mar 02, 2015 at 17:01

Monday, Mar 02, 2015 at 17:01
Chris! I wish I could lay claim to the idea and it is brilliant, and simple! A guy named Ray on Patrol 4x4 got someone to make it up for him and it works well, I simply copied it. We have used it on a few fairly easy snatches and and no drama. Even if the round bar did bend, it is black bar, it would not snap off and stay with the snatch strap, it would simply bend and let the bare strap go. As i mentioned, most of the weight is placed on the square 6mm wall tube and minimal on the round bar. I have also incorporated one into my removable second spare so i have the option when the spare is in the tow hitch! Regards, Michael
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Follow Up By: Michael ( Moss Vale NSW) - Monday, Mar 02, 2015 at 17:08

Monday, Mar 02, 2015 at 17:08
Forgot to mention, the unit in the lower two photos weighs 2.4 kg. Michael.
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Follow Up By: Idler Chris - Vic - Monday, Mar 02, 2015 at 17:38

Monday, Mar 02, 2015 at 17:38
I have two rated anchor points on the back of my vehicle and I use a bridle between them. I have it this way because my Cruiser can be 3.5 tonne and if seriously stuck and I needed to be recovered backwards this, I feel, is the safest. The problem is that when I am recovering someone else my end is strong but I have no control of the their end, and if it lets go then I cop the flying shackle. What I am going to do is make one of these receivers with the round cross bar a bit smaller so that it becomes the weakest link in the recovery, because as you say if the round bars bend and the strap slips off its is no big deal. If this happens I go to plan B and turn the truck around and use the winch. It just goes to show you are never to old to learn, thanks Michael.
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Follow Up By: Michael ( Moss Vale NSW) - Monday, Mar 02, 2015 at 18:32

Monday, Mar 02, 2015 at 18:32
Chris, Probably try 16mm diameter black bar. The round bar is 190mm long, you need this long at least so it cant slip off one side with a normal looped snatch strap. Michael.
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Follow Up By: Drew - Karratha - Monday, Mar 02, 2015 at 19:34

Monday, Mar 02, 2015 at 19:34
What would be wrong with putting the pin of the receiver through the loop in the end of the snatch strap? The pin is as big (or bigger) than the pin of a shackle, there is no way the pin can become a projectile, there is nothing else to be a projectile apart from the strap itself (and that should have a dampener on it anyway). To me, adding anything to it (the device shown, or the commercially sold recovery hitch) only adds to the chance of a potentially fatal projectile...
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Follow Up By: Roachie.kadina.sa.au - Monday, Mar 02, 2015 at 20:16

Monday, Mar 02, 2015 at 20:16
Drew... Playing devil's advocate for a moment, if I may....

When you say: " there is nothing else to be a projectile apart from the strap itself"....I hope you are correct.

The potential problem (in my eyes) is that we have virtually no control over the next step/s in the mounting. Take for example the above pic of that nifty box-section with the solid steel bar. Great bit of gear for sure and I would have every confidence in it not failing.

However, what is THAT attached to? Well, let's see: It is mounted in the vehicle's standard tow hitch receiver (Hayman Reece or similar). That box section is welded to the main section of the tow bar assembly. Accordingly, we have to have faith in the welding quality of that joint.

The cross-arm of the towbar usually has 2 sections (one at either end)of heavy gauge flat (or angle) steel which is bolted to the chassis. In many of these set-ups the cross member is attached to these 2 end brackets via welds, but the square box section is mounted through square holes in those end pieces. That is good news.

What about the bolts that hold the total towbar assembly to the chassis? Are these "rated"? Even if they are....have you ever had a gander inside the chassis cavity? In many instances the bolts are held in place by welded captive nuts put there by the original manufacturer and designed to hold the original bumper bar in position.

Accordingly, in my mind, it would not be unreasonable to doubt the integrity of those bolts and/or the captive nuts....they are simply welded to the relatively thin steel that forms the chassis.

If any ONE of those items lets go there could be some clean undies being required by driver/s and/or bystanders.

Roachie
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Follow Up By: Idler Chris - Vic - Monday, Mar 02, 2015 at 20:45

Monday, Mar 02, 2015 at 20:45
To Drew, nothing wrong with putting the eye of the strap into the towbar receiver in 99% of all recoveries, its a very common practise. Just be aware that while its rare I have seen the pin bend a bit making getting the pin out a nightmare. With a receiver in the towbar the forces on the pin are on the sides whereas if there is a strap being held by the pin the force is in the middle of the pin.

To Roachie, me thinks you have been at the devils juice. lol
Everything you say is correct of course but this post is really about shackles and one assumes (maybe incorrectly) that if the towbar is rated to pull the maximum load applicable to the vehicle that it is also strong enough to effect a difficult recovery. If you look at recoveries gone wrong on You Tube you see plenty of flying shackles going through body panels and windows etc, but when the whole bullbar or the backside of a vehicle lets go they don't tend to go through windows and body panels. Having said that next week when the Cruiser is on the hoist I will inspect the fitment of my towbar and satisfy myself of its strength and its abilty to effect a heavy recovery.
Thanks again Roachie I hope others have learnt as much as I have from this post.
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Follow Up By: Drew - Karratha - Monday, Mar 02, 2015 at 20:46

Monday, Mar 02, 2015 at 20:46
Agree 100% Roachie! But....... If the whole towbar assembly lets go - that is bad (very bad!!). I don't think putting the strap through the receiver pin would make the whole assembly part company any sooner than adding the 'recovery hitch' to it, it is just that you are adding another potential projectile into the recovery for (in my opinion) no good reason... And please correct me if I am wrong as I'm not an engineer, nor do I have any qualifications in any area that would make my thoughts any better than anyone else's (but I did snatch out 2 jeeps last week - both wanting to put the loop over the tow ball.....- I refused...)
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Follow Up By: gbc - Tuesday, Mar 03, 2015 at 19:49

Tuesday, Mar 03, 2015 at 19:49
On most bars with just towballs, you can start by opening the strap eye and sliding it completely over the bar and ball. Then twist the loop and bring it back past the ball. This way the towball bears no load, but it does help locate the strap very similarly to the crossbar setup above. Caveats for this type of attachment would include checking the tow bar for sharp edges which will cut the strap eye.
For the bloke worried about eye strength when joining straps, it simply isn't true that eye strength is diminished when the strap is reeved about another. They are meant to do that. Finally, there isn't a shackle manufacturer on the planet that rates a shackle for dynamic loading. It may be common place to use shackles with snatch straps and closed recovery loops, but that certainly doesn't make it right. Snatch straps go on hooks or nothing. Recovery loops and shackles are for winching.
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Reply By: Batt's - Sunday, Mar 01, 2015 at 00:43

Sunday, Mar 01, 2015 at 00:43
Shackles have been designed to be used in a manner where you attach the pin side to the load and the Bow or D to the sling this will help to reduce the amount the pin comes undone when moving the sling around it will help prevent it possibly pinching fabric slings n the pin and if the pin gets scuffed up due to rubbing on metal lugs/lifting points it can be replaced only with the correct size pin and your sling is out of harms way always being used on a smooth surface at all times. It's an individual choice and you don't have to leave the pin done up tight for an individual recovery or when lifting something it can then be easily removed and rigged again because sometimes you need to do this quickly lots of different circumstances involved especially when lifting with cranes. Backing the pin off half a turn can also be important when lifting very heavy items because if you don't when you take the weight you can potentially tighten the pin considerably when the load is taken up and it then may be difficult to undo it. If I was towing someone which I have done several times for an unusually long distance I would definitely nip it up with a shifter because the pin can come undone, bolt pin shackles are advisable to be used if leaving you shackle done up for considerable lengths at a time of permanently. With some of these aftermarket recovery hitches they also have the potential to cause damage for the unwary especially if the supplier suggests you can fit 2 for a vehicle that was only designed to have 1 fitted by the car manufacturer this can place stress on the chassis where it wasn't designed to have it placed potentially creating damage to the chassis etc.
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Follow Up By: Batt's - Sunday, Mar 01, 2015 at 00:52

Sunday, Mar 01, 2015 at 00:52
Forgot to add you can position the shackles when lifting so that it doesn't tighten up but you don't always remember to do that.
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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 08:43

Sunday, Mar 01, 2015 at 08:43
Thats great Batt's. As I have already said lifting and vehicle recovery are two different things. What this highlights to me is that in the lifting industry the equipment being used is NOT owned by the user. It is supplied by the organisation they are working for and is used by many others. As there is a profit motive the equipment they use may not be in first class condition and is most likely one of the reasons why there are so many Standards in the lifting business. In vehicle recovery you are in control as you are using your own equipment which for most, if not all, of us in first class condition. If I had a shackle that was in anyway damaged I would replace it. However faced with no choice and a shackle with a rough pin I would still attach the strap to the pin as there is little movement of the strap on the pin and I would prefer the shackle to be pulling straight and so at its maximum strength. The reader now has more information and can make better decisions as to which is the safest way to use a shackle in any particular situation.
Batt's also made an interesting comment about tightening the pin. I said I always do the pin up as tight as I can by hand on the basis that it is no big deal if I have to go to the tool kit to get something to undo the pin. What Batt's has said is that there could be situations where it maybe necessary to be able to undo the shackle quickly in which case backing the pin off a bit is the best (safest) thing to do. As no two recoveries are the same the user will have to assess, and decide on the safest way.
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Follow Up By: pop2jocem - Sunday, Mar 01, 2015 at 12:46

Sunday, Mar 01, 2015 at 12:46
From experience the weak point in vehicle recovery generally is the method that is used to attach the shackle to the front or rear. There are some nice videos of bumpers and 'roo bars being removed in their entirety from the front of vehicles. Fortunately the sheer mass of a 'roo bar doesn't allow it to go too far. Well most of the time.
The dangerous objects that are likely to get accelerated to dangerous speeds are the shackles themselves together with the tow hook that was holding them to the chassis because the bolts that were holding them, or the point they were attached, were inadequate.
With a safety factor of around 6 times the rated capacity, lifting gear has a fair safety margin to cope with shock loads.
Keep in mind that this degree of margin may be needed to allow for the sudden failure of a piece of equipment or loads slipping in the crane (lifting) industry. Pieces of equipment such as snatch straps are never used in that application for obvious reasons. Therefor when a component of the lifting gear is called upon to arrest a falling load the shock is quite substantial because no part of that equipment has any appreciable elasticity. The snatch strap on the other hand relies on that elasticity and the ability to store and use the kinetic energy of the towing vehicle to assist in the recovery process without the sharp instantaneous jolt of non elastic gear.
To allow this ability to store and use that energy in the most effective way the chosen snatch strap should always be matched to the mass of the vehicle to be recovered.
Not much point using a 12,000 kg rated strap to recover an 800 kg Suzuki.

A correctly rated shackle should never be the weak point in any recovery.

Cheers
Pop
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Follow Up By: Batt's - Sunday, Mar 01, 2015 at 14:36

Sunday, Mar 01, 2015 at 14:36
But quite often in the real world you don't carry multiply sized straps so what you have at hand will do the job and will work fine as long as you use common sense
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Follow Up By: pop2jocem - Sunday, Mar 01, 2015 at 17:52

Sunday, Mar 01, 2015 at 17:52
You're quite right Batt's, unfortunately that particular commodity (common sense) seems to not be included in many vehicle recovery kits or the owners thought processes.

I personally haven't seen it advertised in any catalogues.

Cheers
Pop

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Follow Up By: Bob Y. - Qld - Monday, Mar 02, 2015 at 19:29

Monday, Mar 02, 2015 at 19:29
Pop,

They were selling it at Bunnings, aisle 31, as I recall.

Seems they no longer stock it as most people didn't know how to use it. :-)

The Saturday morning training sessions "How to use your Common Sense" were poorly attended as well, and this led to the product being taken off the shelves. :-(

Bob



Seen it all, Done it all.
Can't remember most of it.

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Reply By: HarryH - Sunday, Mar 01, 2015 at 11:06

Sunday, Mar 01, 2015 at 11:06
Have not used this soft shackle but it could well be a good thing? link below.
soft shackle
AnswerID: 546758

Reply By: Peter_n_Margaret - Sunday, Mar 01, 2015 at 11:10

Sunday, Mar 01, 2015 at 11:10
If you do ever use a shackle, make sure it is NOT the weak link in the system and that the strap breaks first if something breaks.

Cheers,
Peter
OKA196 Motorhome
AnswerID: 546759

Reply By: Shaver - Sunday, Mar 01, 2015 at 12:08

Sunday, Mar 01, 2015 at 12:08
Idler Chris,

As a ex Army Recovery Mechanic (Rec Mech) there are 3 types of Shackle that I am aware of and they are a "D Shackle" - "Bow Shackle" & a "Plate Shackle. By your statement I would imply that you are referring to a "D Shackle" which is used for straight line pulls with no side force. The "Bow" is used where there is likely to be a side force. The "Plate" is used normally to join 2 lenghts of SWR together. There are various Recovery lay outs when winching such as straight line pulls, belly pulls, compound layouts & compound compensating layouts each with there own benefits & advantages. To imply that there is no Standards in Recovery than may I suggest Course's in Army Recovery. Also you do know what forces apply in a TPR as Ground Resistance, Degrees of Slope, Turning Resistance, Frictional Losses, plus a 25% safety factore are formulated in before any attempted recovery takes place. If you are recovering a 50 ton Tank with a 20 ton winch even before the winch turns you know exactly what is going to happen. There is nothing more frightening than to hear a SWR "Sing" & sparks fly off the winch drum after it lays on from the fairlead I can assure you. Cheers !
AnswerID: 546764

Follow Up By: Member - mike g2 - Sunday, Mar 01, 2015 at 16:38

Sunday, Mar 01, 2015 at 16:38
Hi Chris , as an ex ARes, I also learnt a lot about 4x4 in Army, then followed up with 2 civ courses. cant get much better than Pilbara Regiment exercises or 10 TPT tng + field exercises in some of the toughest country around . Clubs are also excellent for gaining experience, giving back to the community, learning about track care, working with the authorities, enjoying the camaraderie of likeminded people....
To all: - Any tng course + experience is better than none. agree that standards DO exist, as in my post check - aust standards for RTO 4X4 courses.
Had the experience once of being in a 3 Tn Parenti 4x4 ambulance in Pilbara and helping pull someone from mud in mangroves- the stuck vehicle started to pull us in when we put pwr onto our winch!
I say, avoid the need for recovery in first place whenever poss by use of appropriate tyre pressures, vehicle loading, gearing and (common) track sense . Minimal use of any object capable of becoming a missile is good - can add a 'secondary tie' to shackle- short piece of 100lb fishing line trace or 2mm braided nylon ? this may act as a damper/retainer.
PS: I have seen someone bog into sand near Lancelin who had driven onto beach in a small sedan car!!
MG
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Follow Up By: Shaver - Sunday, Mar 01, 2015 at 18:22

Sunday, Mar 01, 2015 at 18:22
mike g2

The trouble is the old memory is getting on now with a lot of the experiences being lost in time. I was a Regular & done 6 Years with time spent in Vietnam with my trusty old M543 6x6 Wrecker (23ton with a full CES). When one looks back you could write a book on some of the incidents that happened. I remember one occasion in Aust up at Shoalwater Bay Qld, whereapon we had to extract a Cat 966B in poring rain that had sunk up to the drivers seat. Never seen a place like it, if you jumped onto the ground it shook all around you, & once the surface was broken everything sank like quicksand. I think from memory it took a 4 to 1 indirect with a 24ton winch to extract him. They ended up calling off the exercise as it never stopped raining at the time. I know that the whole time I was wearing soaked clothes as you couldn't dry anything. Cheers !
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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 23:03

Sunday, Mar 01, 2015 at 23:03
The "secondary tie" idea is another good one. You get called on from time to time to assist someone who has got themselves stuck. Unfortunately some of the time they do not have proper anchor points. If their anchor point lets go its you who wears the flying shackle. What I do in these situations is to put the eye of Tree Trunk Protector into the shackle used to attach the snatch strap to the recovery point and tie the other end to the bull bar or other suitable places. Then if their recovery point lets go the flying shackle will be held back by the TTP.
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Reply By: pop2jocem - Sunday, Mar 01, 2015 at 18:08

Sunday, Mar 01, 2015 at 18:08
Maybe another facet of the recovery process that needs mentioning is what I consider to be primary preparation even before starting out on the snatch strap or winching phase.

By this I mean when having a heavy 4B bogged to the belly plate and diffs with all 4 wheels spinning, doing a little work with the long handled shovel to remove as much as possible the mud, sand or bloody big rock that brought you to an unscheduled stop.

I am sure some of you will have seen a rescue attempt where the vehicle is in that unfortunate forward momentum deprived situation. Out comes the snatch strap, the recovering vehicle backs up, hooks up, and then takes off like a bat out of hell using the full slack length of the strap for his run up and then wondering why his mates car is still in the bog and the attaching hardware is now buried in his tail gate.

Quite often all it would have needed was a little preparation and just maybe the stuck vehicle could have been pulled free with a lot less drama and danger to all concerned.

Cheers
Pop
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Follow Up By: Idler Chris - Vic - Sunday, Mar 01, 2015 at 22:51

Sunday, Mar 01, 2015 at 22:51
Another good idea with a seriously stuck vehicle is to use recovery tracks as well as the snatch strap. I little bit of extra work but much safer.
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Reply By: Louwai - Monday, Mar 02, 2015 at 15:38

Monday, Mar 02, 2015 at 15:38
There are many great comments & suggestions here.

I think a general knowledge of rigging & lifting gear would be a good thing. We are talking about vehicle recovery & towing, but the general basics of lifting & rigging apply as well.

Individuals should acquire knowledge about rated equipment from a Rigging & Lifting specialist. Places like A.Noble & Son, or Bulivants, etc.
Nobles produce a booklet called "The Riggers Handbook". Highly recommended & very informative.

A person should;
Understand your vehicle weights & loads. Understand what equipment is required & purchase the most suitable equipment.

An understanding of how the usage configuration can either significantly increase or decrease the strength of a strap. eg. What forces are exerted if you bend & "hitch" the strap eye rather than use a shackle?
What happens to a strap if you put it around a tree & then shackle the end back onto itself??

Understanding what forces you put onto the recovery points if you use a bridle & under what conditions. eg, Std recovery points are designed for a direct straight pull, but a "Bridle" will apply load the the point on an angle. How will this effect the recovery point? Could a side load rip a std point from the chassis??

Understanding the shock-loads that are present during a recovery.


Almost all individual recovery components are designed for a straight, direct pull / load.
The slightest change in pull / load direction can have a big effect on the strength of all components within the set-up.
AnswerID: 546836

Reply By: Member - Munji - Monday, Mar 02, 2015 at 17:02

Monday, Mar 02, 2015 at 17:02
Idler Chris

Backing off the pin is only done that way because people are generally lazy.
The bow shackle pin is designed so that you can leave it tight and undo it with either a pin or a spanner hence the shape of the pin head.
Also bear in mind that rigging techniques used in the lifting industry are mostly best practice rather than a set standard.
Usually when lifts are being done the slings need to be at either a 30, 60 or 90 deg angle so the bow allows them to straight line from the shackle itself where this would not be possible if connected to the pin, they would all be crimped together.
Bow shackles also have a safety factor which in a technical sense increases its mark WLL.
AnswerID: 546837

Follow Up By: Batt's - Monday, Mar 02, 2015 at 18:23

Monday, Mar 02, 2015 at 18:23
You're completely wrong about people being lazy especially if you're working/hanging off scaffolding or building structures the less tools you need to carry the better and the quicker you can fit or remove shackles the better as well especially in windy conditions where the boom of the crane can be moving several meters at rest getting things done quickly, safely and keeping your hands in high risk areas for minimal time between wind gusts is important. Just remember it's not a perfect world with perfect conditions so risks are taken and sometimes can't be avoided because it's not always factored into the engineering of things quite often inexperienced people think everything can be done without risk in the real world that's not true. All shackles should be used in a straight line, side loads should be avoided but if they can't the wll will be reduced accordingly for a 90 deg angle a 50% reduction in the wll should be implemented. One more thing bow shackles have the same rating as it's equivalent d shackle eg if you have a 10 mm bow it's good for 1 ton same as the d shackle and it stays the same throughout the size variations.
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Follow Up By: Idler Chris - Vic - Monday, Mar 02, 2015 at 21:07

Monday, Mar 02, 2015 at 21:07
I think we are mixing apples and oranges here. Munji is referring to vehicle recovery and Batt's to a lifting situation which are different, and I agree with both of them. With a vehicle recovery the vast majority of the time you have the time to get a tool if the shackle pin is to tight to undo by hand. As Batt's pointed out in the lifting business you do not have the time the vast majority of times. Every vehicle recovery is different and if I considered that it may be necessary to be able to quickly release the strap then I would back the pin off a bit. For the rest of the time I will do the pin as tight as I can by hand and if I have to get something to undo the pin, well so be it, at least I will feel I have done it more safely.
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Reply By: Mitchelll - Tuesday, Mar 03, 2015 at 21:13

Tuesday, Mar 03, 2015 at 21:13
Weak links and components most likely to fail:

In an isolated system of 1 vehicle recovering another through the use of a snatch strap in a standard, idealised, straight line pull, what component should be the weak link?

The snatch strap? (Seems to be the general consensus)

If the snatch strap is to be the weak link, how much stronger should the bow shackles be? Factor of Safety etc
(My workplace mandates that snatch straps be attached via rated shackles to the rated recovery points affixed to the vehicles or via the pin in the rear tow receiver when the tow hitch is removed.)

In light of this research http://ro.uow.edu.au/engpapers/2956/ do bow shackles rated for static loads behave in a similar way under dynamic loads? (ie a snatch recovery)
"Both new and heavily worn karabiners were tested open and closed, and results from static and dynamic tests were compared. We found that the dynamic failure loads of closed karabiners were up to 50% lower than the failure loads in static tests ... "

Has anyone come across similar research for bow shackles?

AnswerID: 546966

Follow Up By: Idler Chris - Vic - Wednesday, Mar 04, 2015 at 00:05

Wednesday, Mar 04, 2015 at 00:05
I would not worry to much about the strength of a bow shackle. Your chance of breaking a bow shackle in good condition in a vehicle recovery I would suggest is zilch. A 4.25 tonne rated shackle is rated for a lifting application and with the safety margin you are going to need a force in excess of 25 tonne to break it and no snatch strap can do that. This post is about how you use the shackle because it strength is not in doubt. If a recovery goes wrong about the worst thing that can happen is you have a shackle flying through the air at lethal velocity. The best solution is not to use a shackle at all and there have been a number of good suggestion in this post for people to consider. If you must use a shackle you should take as many step as you can to ensure that that shackle does not become a dangerous missile. As an example the suggestion from Michael from Moss Vale does away with the shackle. You can argue about the merits of it but if it should fail then there is unlikely to be any damage, so on that basis I say it has great merit as it is substantially safer.
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