Is it safe to sideload metal shackles during vehicle recovery?
Crosby Shackle Sideload Chart
This one falls under the heading: Just because it is repeated over and over does not make it true.
How many of you have seen people post or say something along the lines of: "Never, ever side load a steel shackle--sideloading lowers the rated strength of the shackle!!!"?
Note: I may upset a person or two with this one.
I see it all the time. Such misleading statements are a pet peeve of mine. Apparently, these folks only get stuck in parking lots where straight-on recovery is always an option. Personally, I seldom get stuck in really convenient locations. Do you? I have ended up sideways on a snowy shelf-road where you could not pull me forward or to the rear but had to spin me in the road. That required sideloads. That happens in real life. But I digress...
Let's not start out wrong; I am not saying that sideloading a steel shackle does not lower its load rating. It does. I am pointing out how little that may matter for what we do and how we use them. Bold claim? Before you get your bloomers in a twist and start calling names, allow me to explain.
The general point of the claim seems to be that it is **unsafe** to sideload a standard bow shackle due to it not being at 100% of its straight load rating. Let's examine that for a moment.
What if I tell you a sideloaded "rated" 3/4" steel pin or bolt shackle is STILL rated stronger than most other recovery items people use? Yes, for many applications, even at a 90-degree sideload. ASME's overhead lifting rules, which they seemingly try to paraphrase, do not say you should never sideload a bow shackle, either. That is why they specifically state how to rate the load capacity when you do so.
A standard "rated" 3/4" Bolt Type and Screw Pin type shackle (bow shackle) has a rated, tested, and legally specified (for overhead lifting) minimum breaking strength of at least 47,500 pounds. (NOTE: Pin-type (round pin w/ cotter key) shackles are not rated for side loading by their manufacturers, so you should not use them for side loads or for any recovery.)
As already stated, the most commonly used shackle for off-roaders is a standard, 3/4" rated shackle with a Minimum Breaking Strength (MBS) of 47,500 pounds. Crosby, a premier manufacturer of shackles and other materials handling equipment, says we should reduce our rating to 70% of the initial 47,000 lbs. 70% of 47,000 pounds is 33,250 pounds. That is still far stronger than many people's snatch straps or KERRS and multiple times stronger than their winch lines. At a 90-degree sideload, which, let's face it, should not happen very often, if ever, Crosby (and OSHA) tell us to use a reduction of 50% of the initial rating. That is still 23,750 pounds.
How strong is your winchline again? How about your recovery rope/strap? Again, 90-degree pulls should still be avoided for many reasons, but the load rating is still higher than many other recovery components some people use.
Some Crosby shackles have an even higher strength rating and safety factor. That means those specific 3/4" Crosby shackles start with a straight-line rating of 54,000 pounds. 70% is 37,500 pounds, and 50% is 27,000 pounds. For a little more safety overhead, they are a good idea. NOTE: If you have a really heavy rig, you probably should consider 1" shackles instead of 3/4". The numbers will change, but the idea will be the same.
So, if you did not already, you now know that quality, rated, Bolt Type, and Screw Pin type shackles (bow shackles) ARE specifically rated for side loads by their manufacturers.
Nothing I said here means you shouldn't be concerned with sideloading during recoveries. It is undoubtedly STILL a concern and strains components in ways a straight pull does not. Keep bogged (mire) recovery factors in mind (or take the time to learn about them). Shackles are certainly not the only components where sideloading can have a negative effect. Of course, a straight pull, when possible, is the better option.
You should ask yourself: Are my recovery points also up to the task? My straps? My soft-shakles? How about my winch rope? Did I do what I could to reduce the load, such as shoveling or using traction aids? Can I use a snatch block or recovery ring to minimize sideloading? These are all things you should think about.
Remember, every component in a recovery needs to be up to the task at hand. Sideloading a shackle is only one of many areas of concern, but I hope this info will help you understand how it affects your recoveries a little better.