Bumper Shackle Scam?? (1 Viewer)

[vegas702]

I'm very new to recovery - period.
I just finished reading Bill Vista's Recovery Bible
Pirate4x4.Com - Extreme Four Wheel Drive
I found it very informative as to actual weight loads and physics of winching. I'm reading as much as I can. I'm trying to educate myself before I get out there and hurt myself, or worse yet, hurt someone else.

Shackles can be cheap or expensive, but commonly range between only a 2,000 to 5,000 lb. load rating. I found a Crosby Anchor Shackle (used for crane rigging) rated at 27,000 lbs. but costs $199.50.

I have two tow hooks on top of my front bumper (thanks to a mud member recommendation). Each hook is rated at 10,000 lbs. If I use a bridle strap, depending on the angles, I almost double to 20,000 lbs.

Rather than use shackles on a bumper, aren't you better off using a weld on lashing ring? A 5/8 ring is rated at 18,000 lbs. If you weld it to a plate and bolt it on - seems that is stronger than shackles as well (unless you go for the Crosby shackle). I calculate that 4 M10 grade 10.9 bolts will hold just over 45,000 lbs.
BTW - a 5/8 weld on lashing ring will set you back about $10.

Then the question is - do you use a shackle on the lashing ring? I say no - use a clevis hook. My Warn clevis hook, if I measured it correctly, is rated at more than 35,000 lbs.

So ... unless you buy a Crosby rigging quality shackle for $200, are the rest of the shackles the weak link of a recovery operation? I have to be missing something obvious ... EVERYONE uses bumper shackles.

 

[ducktapeguy]

I'm no expert in recovery either, but I did lot of reading trying to figure this stuff out too because it's pretty confusing

You may be confusing working load (W.L.L) with breaking strength. All components are rated for a certain load which is only a fraction of how much weight they can actually carry, the ratio being the Factor of Safety (F.O.S). For instance, according to the Superwinch website, their small shackles are rated at 2 tons, but the actual strength is 24,000 lbs, so the Factor of safety is 6:1. For hoisting or overhead lifting where lives are at stake, usually the F.O.S is much higher, like 10:1 or more. So that Crosby anchor rated at 27,000 lbs might have an actual breaking strength of 270K lbs. It's not always easy to find the ultimate strength of these components, so the only thing you can compare is the rated load, and some ratings are more conservative than others.

In the end, the weakest point of the winching setup is probably going to be winch motor or winch cable which is probably rated much closer to the actual strength. If you look at it, the shackles are usually at least 3/4" in diameter solid steel at the narrowest point, while the cable is typically only 3/8" or less.

 

[vegas702]

Yup Mr. duck - that makes sense!!
After what I did find out about weld on lashing rings - I'm a fan of them. You really can't paint them to match your rig, like most jokers do with shackles on their plastic Rubicons (that have never left pavement).
Weld on lashing rings caught my eye as I was driving to work and I saw a row of them welded onto a heavy trailer. The welded on rings were rigged to hold down a pretty big Caterpillar dozer. Very simple, very cheap, and very strong.
Again - thanks for the explanation.

 

[N22]

One down side of lashing rings is that they rattle going down the road. Which is may or may not bother you. At least with a shackle you can take it out when it's not needed.

That's pretty much the only reason why I haven't welded a pair to my bumper yet.

 

[ducktapeguy]

IMO, the biggest drawback of the lashing ring is the welding. How much do you trust the welder doing it? I wouldn't trust myself or some guy off the street to weld them on, but that's because I suck at welding. I'd take it to my friend who's a certified welder that knows what they're doing, even then i'd always be suspect. It's easy to make a weld look strong, not so easy to make it strong. At least with a shackle mounts on some of the better designed bumpers, the mounts go all the way through the bumper and get welded on both sides. Sometimes they go all the way through and bolt to the frame so the welds themselves don't take the load.

I looked up the 5/8 lash ring, rated load is 6,300 lbs, breaking strength is 18,900. So although it's rated for more load, ultimately it's weaker than a shackle.

 

[Cruiserdrew]

A rated 3/4 inch shackle will be more than strong enough for any rigging job associated with 4 wheeling. You are worrying about a problem that doesn't exist.

Crosby or Columbus McKinnon shackles will serve you well all of your days, and cost about $20 each. So buy 3-4. paint an ugly loud color so you get them back and carry on.

I would avoid the unrated shackles from Tractor supply, 4 wheel parts or Smitty built.

I just went and looked at one of my CM 3/4" shackles. It's WLL (for overhead lifts) is 6.5 tons. The Breaking strength is supposed to be 5 times that. So I'm thinking a breaking strength over 30 tons, is likely not to be the weak point in your rigging. Available on line or a industrial supply places for $20 give or take.

Columbus McKinnon M652P Super Strong Anchor Shackles - 3/4" Screw Pin | Tanner

 

[half k cruiser]

How are you going to hook up to that lashing ring for recovery ?

 

[vegas702]

My idea was a self locking clevis hook. WLL is over 22,000 lbs.
I was thinking that it could be fastened to the end of a strap - instead of a chain. It’s made for a chain - so it probably wouldn’t work.
I’ve been corrected as to shackle strength.
Based on what I’ve read - the last guys to do a recovery with chains was Fred Flinstone and Barney Rubble.

 

[gnob]

Definitely err on the side of safety.
This particular hook is pretty but its 5/8. Your winch is 5/16 or 3/8.

Check out www.factor55.com

 

[ducktapeguy]

Found this shackle test from another site

UNSEALED 4X4 ISSUE 038

Even though they only tested one of each device, I think it's pretty safe to say that most all the winch rated shackles on the market are more than strong enough for the job.

 

[cody c]

I have the weld on D clevis mounts on the front of my 80, no problems, I had the rattle and found some rubber to cram in there so they don't make any noise, but I've seen someone use rubber bushings, like the "herco 1003 round double stud" cut in half so that it rests on rubber.

The nice thing about them is they are harder to steal or loose then a regular shackle, but obviously a lot less portable. I should get some synthetic rope shackles (just have some regular hoisting shackles in the back as well), the OP should read up on synthetic shackles, synthetic winch cable vs. cable (wire rope) and stored energy if he hasn't already.

 

[e9999]

One thing to keep in mind when talking about Working Loads and Breaking loads is that the former is what you don't want to exceed. It's not like "eh, I can have 5 times more load than the WL before I reach the Breaking point, so going 4.5 times over WL is for sure safe". Not a good idea, probably. The whole point of WL is that this the max load the Engineers (admittedly perhaps under lawyers' pressure nowadays) feel confident to say publicly you are safe to use routinely. IOW, above that there may be issues. Surely rare and unlikely, yes, but certainly possible. Maybe unexpected manufacturing defects, previous overstrain because of excessive shock loads, etc. So, yes, the safety factor is there but if it was a sure thing that you could exceed the WL, well then, they would advertise the WL as higher than what it is now, I imagine. So, would I be terrified to use occasionally a load a bit higher than the WL when I have a safety factor of 5? No. Would I do it routinely on purpose? No. If you plan on routinely exceeding the WL for a piece of gear, then get a bigger one, safety factor notwithstanding. Especially since it's rather difficult to estimate the magnitude of a load, especially a shock one, short of measuring it with a cell.
But as to a well-chosen welded tie point, yup, I would think the weak point there is more likely to be the welding than the item unless the welder is very competent. Which may also be a moot consideration if the weak point in the system is something else, like the bumper itself or its attachment points, which I suspect people routinely overlook as a possible issue.

 

[shelfboy1]

ive always used military shakles and after only 50 years of wheeling never had one fail

 

[Kaninja]

7/8" shackles with minimum 4.5t WLL. Never seen one fail ever. A couple in a recovery bag is all you need.....unless you have a Jeep in which case you need 4 mounted while cruising the mall parking lot.

 

[Sonofaskipper]

7/8" shackles with minimum 4.5t WLL. Never seen one fail ever. A couple in a recovery bag is all you need.....

7/8” is a pretty big shackle, and heavy too…maybe a bit over kill? We hang heavy tow gear on deck with 3/4” shackles on the tug boat

 

[MUDZLLA]

SWL for rigging is based on inadvertent dynamic loading I believe. I once designed a clamp-on lifting device (for pulling up and repairing high tension power wires in the mountains of BC) which was to be rated for a 15T pull. To test it I did a 3x SWL lift (45T) using an overhead gantry crane and a smelter pot fresh out of the line. The cable slipped about 6" and thankfully held or it would have flattened the semi-trailer below it. The dynamic loading generated by the slip and grip shook the building and nearly buckled the 100T gantry crane. Anyway I gave my device a pass, but it shows one reason why engineers might tend to over design lifting equipment.
Cheers