Correct use of shackles - Chapter 2

Submitted: Saturday, Feb 28, 2015 at 16:31
ThreadID: 111277 Views:6045 Replies:11 FollowUps:42
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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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