winch equipment

[Cord]

I have a 20,000 lb winch I'm installing on a small loader. I wanted some rigging gear so I bought a couple of clevis's off Ebay. They were rated 12 tons. Looking at the clevis's, I now realize they were rated for lifting, not pulling. They way too large for my application. Anybody know how much a clevis would be derated for pulling?

 

[Shmudda]

Cord,

The clevis is rated for the load that is either stamped or embossed on the side of the thing. It doesn't matter whether the load exerted on the clevis is from pulling or lifting. The load exerted is the same no matter what.

What you have to be careful of in any instance is the impact loading of the clevis if the load is "jerked". That in itself will increase the fatigue factor of the clevis quickly leading to failure.

Craig

 

[excelagator]

I think a lifting clevis normally is rated 2-1/2 times the actual lift rating. Mainly because it is lifting overhead. I maybe wrong on this though!

Dan

 

[KJM]

Here in Oz, lifting widgets like shackles etc are minimum design factor 5.

I use 3.2Tonne shackles for my 4WD recovery - which is naughty - using some of the 5x!

/Kevin

 

[Cord]

Yep, that's what I found: a 5x safety factor for over head applicatons. A 3-4 ton rated shackle will have the capacity that I need and a little resever left over.

 

[SnowRidge]

I have a 20,000 lb winch I'm installing on a small loader. I wanted some rigging gear so I bought a couple of clevis's off Ebay. They were rated 12 tons. Looking at the clevis's, I now realize they were rated for lifting, not pulling. They way too large for my application. Anybody know how much a clevis would be derated for pulling?

I am curious how you can tell the clevis was rated for overhead lifting? Regardless, the working load limit (WLL) is the working load limit. It doesn't need to be derated. The clevises you use should have a WLL equal to or higher than the WLL of the cable on the winch. The actual breaking strength will be substantially higher.

Only buy from sources who state their rating in terms of working load limit. That is what the rating stamped into the clevis should be, but with world sourcing of this kind of stuff, the only way to be safe is to buy from reputable suppliers.

 

[SnowRidge]

Yep, that's what I found: a 5x safety factor for over head applicatons. A 3-4 ton rated shackle will have the capacity that I need and a little resever left over.

Pray that you don't kill someone using 6,000 lb WLL rated hardware with a 20,000 lb WLL rated cable.

 

[Cord]

Pray that you don't kill someone using 6,000 lb WLL rated hardware with a 20,000 lb WLL rated cable.

Not true. A rolling 20,000lb load has significantly less resitance than a lifting 20,000lb load. This is illustrated by the ultimate strength of this equipment. If you take the ultimate strength and divide it by 5 you will get the working load for a lifting application. That means the ultimate strength of the 12 ton clevis's that I bought is 120,000lbs! When you hold the 5/8" winch cable next to a clevis with a 1-1/4" pin that's the size of your hand you'll realize how much redundancy is built into lifting equipment. I am not and will not be using this equipment for lifting so the 5:1 saftey factor is unnessary. A 3 ton shackle rated for lifting will still have a safety factor of 1.5 and a 4 ton shackle will have a safety factor of 2:1. That's more than adequate for a winching application. T

his whole theory was reinforced when I was trying to research my question above. I was on a of the winch mfrs. website where they were talking about using a winch for over head lifting. The winch was capable of lifting overhead, provided two things were provided: one was a brake to hold the load, the second is a safety factor of 3:1. The winch mfr. already had a safty factor of 2:1 design into their winch, but that wasn't good enough for over head lifting. With a clevis rated for overhead lifting, we are simply applying the same theory, but in reverse.

 

[SnowRidge]

A 20,000 lb load is a 20,000 lb load, whether it is horizontal and rolling or hanging vertically off of a roller. You are confusing the weight of the object versus the load on the winch. A rolling 20,000 lb object will not present itself as a 20,000 lb load. It will be less.

But you are trying to equip a 20,000 lb winch, which means you need tackle that can meet or exceed its rating. It doesn't matter what the load is. If it hangs up, the winch will pull until it stalls -- or something breaks. The winch needs to be equipped with cable and tackle that will not break or be subjected to more than its rated working load limit before the winch stalls. The same thing goes for the winch's mount.

In other words, the winch itself must be the weakest link. Anything else is dangerous and can be deadly.

 

[mwb]

A 20,000 lb load is a 20,000 lb load, whether it is horizontal and rolling or hanging vertically off of a roller. You are confusing the weight of the object versus the load on the winch. A rolling 20,000 lb object will not present itself as a 20,000 lb load. It will be less.

I don't think this is the issue; what is rated is the maximum line pull of the winch; the winch does not know what direction it is pulling in. What is the issue is RISK. Overhead lifting is what requires the extra factor of safety. If you are towing a log out of the bush and your system breaks (cable or whatever) then the worst that could happen is the loose end of the cable is flung towards whatever end is still attached (could be through the operator if he happens to be inline with it).

With vertical lifting the RISK is much higher if something breaks; gravity takes over and becomes velocity. ANYONE selling stuff for vertical lift (payload or people) will want to minimise liability and do so by increasing the FS.

Also remember that the winch is rated 20K for the first layer; significantly reduces as additional layers of cable are retrieved. You probably have only 8K on the last layer (where you do most pulling?).

Do you really want a 20K winch attached to your loader arms? I think the fuseable link would be something on your tractor.