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Wizard of Brakes
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Discussion Starter · #1 ·
The number one question I see asked about any device used for recovery is what is it rated at for strength.

A good discussion needs to take place to put all of the various industries and their rules into the proper perspective so that the mixing and matching of safety factors and Working Load Limits is understood so you can make a PROPER informed decision.

The easiest way to start is to give an idea of what one industry "rigging for overhead lifting and crane work" requires typically.

Most devices that will be used with a hoist for overhead lifting of anything have a WLL that is 1/5 of breaking strength as the typical minimum safety factor and they tend to go higher.

Put another way, if a crane wants to lift a 1000 lb. load, the cable on the hoist will be rated at a minimum breaking strength of 5000 lbs and any shackle, sling, or bridle that sees the lifting load will be rated in a similar fashion.

Most all of the devices used in the rigging industry for overhead lifting are specified in that manner. If you want a shackle or d-ring that you can use for a 1000 lb. load, it is marked permanently with a WLL (working load limit) of 1/2 Ton or 1000 lbs. You can calculate the breaking strength at a minimum by multiplying that number by 5 to find out what it breaks at.

I'll get some pictures up tomorrow to compare a few things to show just how ridiculous the recovery industry is but we have to start some where.

So, if we try to apply an unrelated industry's standards to what we use and do during a recovery, what is the WLL of your 9500 lb winch that has a 5/16" steel cable on it rated at 9800 lbs breaking strength?

We learned a few things in the snatch block thread, apply that and start thinking about how much less sense it makes to mix and match industry standards.
 

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Wizard of Brakes
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Discussion Starter · #6 ·
Glad I got my smittybilt XRC 8 for free then ;) Now if only it didn't have a line out speed equal to that of a drunk turtle...
The point really isn't what you paid for your winch or even what it is worth. It is the fact that it isn't a hoist. A hoist is used for overhead lifting, you don't have a hoist so why do you want to apply the standards from one industry to another?
 

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I'm going to guess that the industry standard for rigging cranes and overhead loads is applied with different things in mind such as the 100s of thousands of dollars of damage a break will cause, as well as countless lives potentially lost, especially in an urban setting. I dunno, maybe I'm way off. Maybe the lines are longer and there's more stretching and contracting going on too.

But since you specifically brought up the winch I have a question that I've been dying to ask someone for years, who could provide a good answer. Why is a 10,000# winch only secured with 4 small grade 5 (or metric equivalent) 5/16" (or metric equivalent) bolts? It doesn't seem right, although I have personally seen nor heard of winch mounting bolts breaking.
 

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Wizard of Brakes
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Discussion Starter · #8 ·
I'm going to guess that the industry standard for rigging cranes and overhead loads is applied with different things in mind such as the 100s of thousands of dollars of damage a break will cause, as well as countless lives potentially lost, especially in an urban setting. I dunno, maybe I'm way off. Maybe the lines are longer and there's more stretching and contracting going on too.

But since you specifically brought up the winch I have a question that I've been dying to ask someone for years, who could provide a good answer. Why is a 10,000# winch only secured with 4 small grade 5 (or metric equivalent) 5/16" (or metric equivalent) bolts? It doesn't seem right, although I have personally seen nor heard of winch mounting bolts breaking.
The winch is held to the winch plate with that size bolt because that is what it takes to perform the task at hand. The reason you question it is due to normal lack of understanding (that we are all capable/guilty) of what it takes to perform the task.

I'm investigating building a test stand/bench for testing parts used in recovery to figure out some more things. While digging around looking for the column buckling strengths so I know what size square or rectangular tubing to use, I came across a post on a forum from a guy wanting to know what size tube to use for legs on his stand for a 250 gallon aquarium with a weight of around 2000 lbs or 1 ton.

Several suggestions indicated he should step up to 2" x 2" 1/4" wall square tube. In reality, he needed 1x2 20g rectangular steel tube and it was overkill with a total load capacity for the 4 legs of around 15,000 lbs or 1 leg could carry nearly twice the weight of the aquarium. The recommended size or close to it in 1.5 x 2.5 x 12g or about 1/8" thick walls could carry a total of around 80,000 lbs.

So, when you bolt your winch down with 4 of those little bitty bolts, they have employed a safety factor of twice what it needs to stay put. Put another way, the 4 bolts generate about 20,000 lbs of clamping force to stop the winch from moving around.
 

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I came across a post on a forum from a guy wanting to know what size tube to use for legs on his stand for a 250 gallon aquarium with a weight of around 2000 lbs or 1 ton.

Several suggestions indicated he should step up to 2" x 2" 1/4" wall square tube. In reality, he needed 1x2 20g rectangular steel tube and it was overkill with a total load capacity for the 4 legs of around 15,000 lbs or 1 leg could carry nearly twice the weight of the aquarium. The recommended size or close to it in 1.5 x 2.5 x 12g or about 1/8" thick walls could carry a total of around 80,000 lbs.
I actually had to to figure out almost that exact thing once upon a time (270 gallon tank). I wish I remembered exactly what we ended up using but the nice looking cabinet you see does have a pretty sturdy steel subframe under it. I really miss that tank, although it was a lot of work. Saltwater with live coral tank maybe a hobby that you can waste more money on than jeeps.
 

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Wizard of Brakes
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Discussion Starter · #11 ·
So, if I want an 8000# winch, and I also want to follow this rule... How big is a 40,000# winch?
I've seen a 20,000 lb winch on the front of a widened Suburban and it was big enough that it would probably drop the front of a 4" lifted TJ by at least 2" if you hung it off the front bumper and loaded it with steel cable.

What we need to do instead is go the other way and recognize and understand that our winches are not being used under the same rules. They are not hoists, they are winches. The applicable safety factors from the overhead rigging industry can be used as guidelines to help pick out recovery gear, but they are no way straight across applicable unless you plan to hold all items in the recovery chain to the same standards. If you hold your winch to the same standard, you paid a lot of money for something that has the power of a good come-along.
 

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I would like to see some real world load testing on an average rock crawling outing. Hooking digital recording scale to the end of the winch line during the average recovery to show what the actual pulls are. I would imagine that there would be a few spikes that come close to the stall/breaking point of the line, but I would say that most of the pull is within a 2:1 or greater break/pull amount.

I will agree that marketing/sales has thrown off the perception of what a winch is capable of as compared to a hoist, if people would read the hoist specs, they will find the comparable gear ratio/HP/line size ratings have the 5:1 safety factor already built in.
 

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How much can your winch pull?
I don't really know the math to apply, but the specs for it say it can pull 8k pounds on the first layer of line. That 8k pound pull will put an amount of load on the winch, its internals, motor, gears, whatever the limiting factor is.

So in other situations my winch can pull whatever amount of weight combined with the line layer its on, if there's a snatch block involved, etc that equals the same internal load on the winch that is it's limiting point.

This feels very wordy, but if I knew the math behind it I could just create an equation that would equal the internal load on the winch, but I don't so I have this for my explanation. :D
 

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Correct me if I am wrong.... I am shopping for a winch... and I feel I really don't need the >=10K size, but the catch is the < 10k winches typically have lower duty cycles, features etc. So in the end, folks are mostly paying for run-time, speed, etc.

I have seen a 5000 ATV/Utility harbor freight winch pull a Toyota out of a mud pit where the mud was up in the cab... catch was.. a few minutes on... several minutes off.. and it took a while, but got the job done.
 

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A 5000lb ATV winch may get the job done, but as you found, not very efficiently. You do not want to have a drastically undersized winch and become a trail blockage as you spend 20 min making a 3 minute pull. Using the correct tool for the job in this instance.
 

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I don't really know the math to apply, but the specs for it say it can pull 8k pounds on the first layer of line. That 8k pound pull will put an amount of load on the winch, its internals, motor, gears, whatever the limiting factor is.

So in other situations my winch can pull whatever amount of weight combined with the line layer its on, if there's a snatch block involved, etc that equals the same internal load on the winch that is it's limiting point.

This feels very wordy, but if I knew the math behind it I could just create an equation that would equal the internal load on the winch, but I don't so I have this for my explanation. :D
Your winch can create 8000lbs of tension in the rope, best case scenario. Anything your rope is anchored by will see that force times however many segments are going to it.


Top scenario:
Everything sees 8000lbs, max

Middle scenario:
Snatch block, tree, and everything connecting them sees 16,000lbs, max.
Winch and shackle at the bumper see 8000lbs max (individually).
Bumper as a whole sees 16,000lbs, max.

Bottom scenario:
Winch sees 8000lbs, max.
Snatch block, tree, and everything connecting them sees 16,000lbs, max.
Snatch block and shackle at the bumper see 16,000lbs, max.
Bumper as a whole sees 24,000lbs, max.
Final anchor point sees 8,000lbs, max.

So it's probably safe to say the breaking strength of your tree straps, snatch blocks, and shackles should be >2x your winches rated pull.
 

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Wizard of Brakes
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Discussion Starter · #20 ·
I don't really know the math to apply, but the specs for it say it can pull 8k pounds on the first layer of line. That 8k pound pull will put an amount of load on the winch, its internals, motor, gears, whatever the limiting factor is.

So in other situations my winch can pull whatever amount of weight combined with the line layer its on, if there's a snatch block involved, etc that equals the same internal load on the winch that is it's limiting point.

This feels very wordy, but if I knew the math behind it I could just create an equation that would equal the internal load on the winch, but I don't so I have this for my explanation. :D
Start with the first layer of line. How many wraps does the mfg. recommend be on the drum before you can tension the line at full load? Most of them I've seen literature for recommend a minimum of 5 wraps.

What diameter is the drum?

How many wraps are there total on the first layer?
 
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