Buy SHACKLES that aren't shit

Seeing rigging fail once while under load is enough to make me spend the extra few dollars. A lot of energy gets stored up in straps, ropes, and cables.

 

Could you by chance link me to a set of good shackles with a 3/4 pin?

 

https://factor55.com/product/crosby-34-shackles/

http://www.uscargocontrol.com/Rigging-Supplies-Hardware/Made-in-America-Screw-Pin-Anchor-Shackles

 

https://www.relentlessfabrication.c...oducts/3-4-d-ring-shackle?variant=10054733636

 

Is that a 3/4 pin or 7/8 pin on a 3/4 shackle?

 

7/8" diameter pin on all 3/4 D-rings in my experience, these are definitely 7/8 pin. All our bumpers run 15/16" holes in the recovery points for this reason.

 

I have a custom made one off bunper that only has 3/4 holes..... Fml

 

Drill 'em out if theres enough room on the tabs. Or you're stuck running 5/8 shackles- DEFINITELY get 'the good ones' if you cant go with a 3/4

 

Yea, im gonna have to. Hard to put an entire bumper in a drill press though. Lol. Fml

 

Wanted to clear up some partial information/misinformation about shackles I saw in this thread.

Shackles from a reputable will be designed to meet the standards set in ASME B30.26 Rigging Hardware. The important requirements as as follows:

• Shackles shall be stamped with a "rated load" or "working load limit" (WLL)
• Shackles under 150 ton WLL shall have a design factor of 5.

Note that as shackles differ from most off road recovery gear, in that they are rated by their WLL, not their ultimate breaking strength. Most ratings you see for straps, non ASME rated hook or anything that doesn't specifically give a "rated load", WLL or identify the code it's complying with are giving you the ultimate breaking strength. So your 30,000 lb strap will likely break there. You can go buy slings that comply with ASME B30.9 (and thus have a design factor of 5), but you'll pay significantly more. Here's a 20' sling with a 31,000 lb capacity. It's $610 and weighs 36 lbs.
https://www.grainger.com/product/LIFT-ALL-20-ft-Eye-and-Eye-Round-Sling-38Z242

3/4" is not a WLL, it's simply the diameter of the shackle at the bow. A manufacture can select from many materials as long as they're suitable for use.

That said, typically, for 3/4" shackles, you'll find the following WLLs.

Carbon - 4.75 tons
Super Carbon - 6.5 tons
Alloy -7 tons

For typical rigging applications, you'll find carbon shackles, as it's easier/cheaper to get a larger shackle if you need more capacity than buying one of a different material. You typically only use the super carbon or alloy if you can't tolerate an increase in size or weight.

While I'm not a shackle design engineer, I am a design engineer. It's extremely unlikely anyone is designing this type of stuff where it would yield at the design load, it will be firmly on the elastic side of the stress strain curve for the material (read no plastic deformation, or yielding). After applying the required 5 times design factor (manufactures will also add some additional design factors on top of this), a 4.75 WLL shackle should no experience any permanent damage or failure till over 47,500 lbs. Breaking strength would be above that. Obviously, this is for equipment in good condition and used properly.

EDIT: B30.26 defines design factor as "ratio between nominal or minimum breaking strength and rated load..." This means that it's possible a 4.75T WLL conforming shackle could fail at exactly 47,500 lbs. This is unlikely to the be case, as additional margin will likely be added to the design to account for variations in the manufacturing process, variability in the materials, etc...

Real world, I would not expect to have issues with a 4.75 ton WLL shackle to fail or be damaged with a properly applied 20,000 lb load.

Same as above regarding the yield vs design load. It's unlikely anyone is designing shackles using the material ultimate strength.


See this generic stress/strain graph. Except for very specific applications (engine head bolts are a common application), a designer will limit themselves to the elastic (axis to yield) region. That means the yield and failure strength are higher, and the shackle doesn't fail until it passes it's ultimate strength.

The video below is representative of what you can expect from a 4.75 ton WLL rated shackles (failure at 77.5k lb)
https://www.youtube.com/watch?v=66BXmM_JuBI

This is a standard for what the federal government will buy, not what manufactures are designing to. In the US, the industry standard for this is ASME B30.26.

Hopefully that clears up some confusion about shackles. Due to the high factor of safety in the design, they're the off road recovery device I worry about the least. It's far more likely you're going to break a strap or winch line prior to damaging a shackle as long as you're using them correctly.

Just keep the following guidelines in mind:

• Buy a ASME B30.26 complaint one stamped with a WLL from a reputable manufacture
• Inspect for damage prior to every use
• Observe the operating limitations (here's a good primer) https://www.lift-it.com/info-shackle-warning
• Get training if you don't know what you're doing

 

Do you have a link to the standard? As far as I know, the safety factor is based on the breaking strength. A 4.75T WLL shackle would need a breaking strength north of 47,500lbs. Also, I don't think I said anyone was designing them to yield at the design load. I have, however, seen videos of tests of cheap Chinese shackles where the pins have deformed at around 12,000 lbs and won't come out.

 

Try here https://www.astaco.ir/wp-content/uploads/ASME-B30.26-2015.pdf

While there's a few slightly different interpretations, FOS can be based on yield stress (permanent deformation), ultimate stress (failure), or just be an amount above the design load (which will already includes margin). It's industry and application specific as to what's chosen.

EDIT: While the above is generally true, design factor in the context of B30.26 means the "...ratio between nominal or minimum breaking strength and rated load...".

When I said yield at the design load, I meant at the load * 5x FOS.

As for breaking strength, I think you'll find that reputable 4.75T WLL shackles do all have breaking strengths at or above 47,500 lbs. Key word is reputable. I agree with you that you should stay away from unknown or unmarked products.

 

I have personally seen Crosby shackles that deformed (deformed and wouldn't release) at something less than I expected - due to the hideous way they were carelessly loaded. Use of lifting and rigging devices requires a lick of sense.........

 

Thinking about failed recovery gear is frightening. All that energy just "shooting" out is gnarly.

I feel like the only way to go it top quality.

 

It's important to understand how to use this sort of equipment. How is just as important as what......

 

Just to add, at least with Crosby when referring to the size it does not refer to pin diameter. https://www.thecrosbygroup.com/catalog/shackles/crosby-209-carbon-screw-pin-anchor-shackles/

 

https://www.thecrosbygroup.com/catalog/shackles/crosby-209-carbon-screw-pin-anchor-shackles/

 

Load direction plays a huge roll in working limits. This why I point people to Crosby's web site as one will see Crosby's shackles have markings and they all mean something. Plus on there website if you do a looking one can educate themselves on all what it means and get a basic understanding of forces and loads.

 

This where I would suspect most get into trouble. (Real world, I would not expect to have issues with a 4.75 ton WLL shackle to fail or be damaged with a properly applied 20,000 lb load.) As well as if it is a static or dynamic load. We all have seen videos of people trying to get a running start with slack in the strap at significant angles then we all see what carnage that creates. Great write up by you.