Wild Coast
Member
Was confused by the various 'ratings' I saw on different shackles, ended up doing some research to understand, figured I'd share - I'm sure others will find this useful.
Amazon and other offroad sites are full of cheap D-shackles. You can get them for less than 10 bucks. However not all shackles are created equal, even if the 'rating' on the shackles makes it appear so.
Lets take these shackles on Amazon as an example: FieryRed 3/4" D Ring Shackle (2 Pack) 22,046Ibs Break Strength
To be considered 'rated' a shackle must have the WLL (working load limit) listed on the shackle. And these, like all 3/4" D-ring shackles are standardized at a WLL of 4-3/4 ton (4.75 *metric* tons) - this is equivalent to 10,471 lbs.
However, different manufacturers use different quality materials and the actual failure-rating of shackles with the same WLL of 4.75ton varies widely. This failure point is expressed as a ratio to WLL and referred to as the Safety Factor. When the above shackles say 22,046lbs failure point, that means that their Safety Factor is 2.1:1 (22,046lbs / 10,471 lbs).
A safety factor of 2:1 is actually pretty poor as far as shackles go and doesn't give you much room for error. The stress put on recovery gear is far far higher than the vehicle weight when any sort of dynamic forces are involved. So if you have a 6000 lbs truck, you can easily be putting x3 that if the vehicle jerks/slips. Well, 6,000lbs*3 is 18,000 and that's below the listed 22,046 lbs failure point you say, no problem, right? Actually NO, the problem is, if a shackle is ever side-loaded (45 degrees from straight pull) it loses 30% of it's WLL! If you side load a shackle fully side-ways (90 degrees) it drops 50% of it's WLL. To have a shackle rotate on your anchor in a jerking recovery situation such as when using a snatch strap is pretty easy. So suddenly your failure point is 22,046 minus 30% = 15,400lbs. Or if it's 90 degrees side loaded you get 22,046 minus 50% = 11023lbs. This is below the 18,000 lbs force your vehicle is putting at the shackles. SNAP! This is why these cheap shackles DO fail on people...
If you look at high-quality shackles such as those made by Crosby or Columbus McKinnon, they have a Safety Factor of 5:1 or 6:1. This means that they fail at 10,471*5 = 52,000 lbs!! Lots of safety margin for any sort of 4x4 recovery. That's why these are actually rated for rigging work. Sure, they're a bit more expensive, 30$ a pop, but the way higher safety margin is worth the extra 15$ I think. If this is resonating with you, just fyi: Factor55.com sells Crosby shackles which are epoxy powder coated if you like nice black or red shackles.
Just food for thought, figured I'd share so others benefit and can make an informed decisions.
Amazon and other offroad sites are full of cheap D-shackles. You can get them for less than 10 bucks. However not all shackles are created equal, even if the 'rating' on the shackles makes it appear so.
Lets take these shackles on Amazon as an example: FieryRed 3/4" D Ring Shackle (2 Pack) 22,046Ibs Break Strength
To be considered 'rated' a shackle must have the WLL (working load limit) listed on the shackle. And these, like all 3/4" D-ring shackles are standardized at a WLL of 4-3/4 ton (4.75 *metric* tons) - this is equivalent to 10,471 lbs.
However, different manufacturers use different quality materials and the actual failure-rating of shackles with the same WLL of 4.75ton varies widely. This failure point is expressed as a ratio to WLL and referred to as the Safety Factor. When the above shackles say 22,046lbs failure point, that means that their Safety Factor is 2.1:1 (22,046lbs / 10,471 lbs).
A safety factor of 2:1 is actually pretty poor as far as shackles go and doesn't give you much room for error. The stress put on recovery gear is far far higher than the vehicle weight when any sort of dynamic forces are involved. So if you have a 6000 lbs truck, you can easily be putting x3 that if the vehicle jerks/slips. Well, 6,000lbs*3 is 18,000 and that's below the listed 22,046 lbs failure point you say, no problem, right? Actually NO, the problem is, if a shackle is ever side-loaded (45 degrees from straight pull) it loses 30% of it's WLL! If you side load a shackle fully side-ways (90 degrees) it drops 50% of it's WLL. To have a shackle rotate on your anchor in a jerking recovery situation such as when using a snatch strap is pretty easy. So suddenly your failure point is 22,046 minus 30% = 15,400lbs. Or if it's 90 degrees side loaded you get 22,046 minus 50% = 11023lbs. This is below the 18,000 lbs force your vehicle is putting at the shackles. SNAP! This is why these cheap shackles DO fail on people...
If you look at high-quality shackles such as those made by Crosby or Columbus McKinnon, they have a Safety Factor of 5:1 or 6:1. This means that they fail at 10,471*5 = 52,000 lbs!! Lots of safety margin for any sort of 4x4 recovery. That's why these are actually rated for rigging work. Sure, they're a bit more expensive, 30$ a pop, but the way higher safety margin is worth the extra 15$ I think. If this is resonating with you, just fyi: Factor55.com sells Crosby shackles which are epoxy powder coated if you like nice black or red shackles.
Just food for thought, figured I'd share so others benefit and can make an informed decisions.
