Yoda I kept the tags on my chains. I just went out and took pics. They're hard to read but for my 2907RSTS the chain is 11,700.

And I use hammerlocks to connect to the hitch. Update: Got the X-015-13 from tulsachain.com. 1/2" 15,000 pound. Although they're available everywhere.

Terry

Thanks for posting Terry - I think your choice of the hammerlocks is a lot better than what others appear to be doing.

Interesting information on the tags.
You trailer GVWR is just shy of 10K and the chain break strength (not working load limit) is 11,700lbs. Not much of a safety factor (my opinion) but appear to meet regulations. If I am reading the tag correctly they are 5/16 grade 40.

My dad had a boat trailer come off once and it broke both safety chains. Made a mess of the hitch. Fortunately he was going slow out of the marina across some RR tracks.. He forgot to lock it, or it did not lock correctly - lock pin was missing. I think I was 16 at the time - big lesson learned.

Thanks for posting the tag pictures . I wonder if they are different for different GVW TT's.

Keith

The more I look, I think it's 5/16 grade 43. I don't see a grade 40 looking online. And 43 is 11,700 break strength.

So now the question. One chain has an 11,700 break strength. Are those numbers additive when you have 2 chains? Or something less since you can't be assured of equal stress when something let's go.

Lastly, I'm not sure about the little loop welded to the frame that the chains connect to. It doesn't look like it would be any stronger than a single 5/16 chain IF even that strong.

Terry

All good questions. Hopefully a chain expert will come along. A picture of the welded loop would be good if possible.

In my OSHA construction safety class they went though everything including what chain could be used of lifting etc (grade 80 I think). They also covered what to look for such as stretched links or improper welding and the use of lower rated attachments (hooks, loops, shackles) than the chain rating. This was in the early 2000. He indicated he liked to see a 3x chain rating to the load or more and when double chaining each chain should be 3x in case one broke for some reason the other would hold. He talked about failure modes that the load could double or triple as the weight shifted and jerked. This may have change. Good catch on the grade 43.

Good thoughts and discusion
Keith

We needed chain extensions when we added our Propride P3 hitch. ( we bought used and I didn't trust the extensions that came with it since I didn't know the rating) My chains are rated around 10K ( unit is 8500) so I chose these double clevis links to attach the added length of chain. And bought the highest rated chain I could find to meet the camper weight. It wasn't quite as high as the original but covered the camper weight.

https://www.tractorsupply.com/tsc/pr...c?cm_vc=-10005

They are rated for 9200 lbs

Keith, Standard chain (gr 43) has a MBL of 3x the rated working load for transport / lashing operations. Grade 70 lashing chain is 4x WLL for MBL. And lfting chain is typically grade 80 or 100 and again 4X WLL for MBL. Not knowing but guessing that the bar they use on a 5/16" chain is probably a grade 36 3/8" diameter (guessing here no Trailer with chains close to measure). Pure tensile load of single 3/8 bar should be about 3,900 lbs (single bar) this is neglecting any angles, bends, etc.

We use a lot (miles) of chain at work yearly for lashing for a client that requires new for each load. https://www.columbusmckinnon.com/glo...3-brochure.pdf we use the Gr 70 stuff (and on some loads have 10+ chains and binders) https://www.columbusmckinnon.com/glo...0-brochure.pdf

The spring retainers used on the trailer hooks prevent proper attachment to some of the newer factory hitches. With them removed it still takes a bit of trial and error to make a proper connection. On the 17 and 18 GM (only ones I have access to), the hook needs to be pushed up through the bottom holes then the free end ran out the rear hole, then pull the hook back through the bottom hole. (almost need a video to explain it)

I think the only reason TT chains have tags has to do with Canada Requirements. All of our Canadian equipment chains must have a tag similar to the ones found on travel trailers. None of my utility trailers have such tags on the chains.

Here's the pic of the welded loop. 0.443 so guessing it's 7/16 stock if you account for my potential error in measurement.

Yoda Agreeing with Joseph Jlawles2 , Years ago I owned an auto towing company. All of our equipment carried 5/16 grade 70 transport chain, which was required by DOT, CHP and probably others for the light class of tow trucks. Bigger equipment, say medium duty and up, requires heavier chain, but I believe it is still grade 70. Increasing chain size exponentially increases capacity. From memory, safe working load was 4700 pounds, one third of breaking strength. But that rating was for binding down (putting tension) the victim vehicle to the truck. We also used this chain as a safety chain, because that is what the truck was equipped with. In that use, it was overkill. Never came close to a failure, though. The weakest link....is probably at whatever connection device is at the end of the chain. Some have weight ratings, and some don't. I would be leery of a chain attachment without a rating. Since we aren't lifting anything, I think the breaking strength is going to be the relevant rating here. If I were starting from scratch, a 50% margin up would seem reasonable. So if you had a 10K gvwr trailer, you would want two chains each with a breaking strength of at least 7500 pounds, as a minimum.

My .02

Dave

Here's a link for a great document that provides the specifications for different types of chains.

https://www.fehr.com/img/product/des...ifications.pdf

Helpful post--thank you. I'm going to copy it to the Reference Material section. (The engineers here will geek out for sure over the information in the PDF!)

Just an observation: The safety chains do not need to carry the full weight (GVWR) of the trailer. They do need to support the tongue weight plus impact loading from when the hitch jumps off the ball and drops. They also need to be able to take the tension of the trailer's lateral movement as it is first towed by the chains and then restrained by the chains during braking. With that said, sizing the chains so that each could support the GVWR is probably as good a method as any and a lot simpler than trying to come up with the actual load (there are probably mechanical engineers out there already salivating at the thought of tackling this problem).

A second observation is that under ideal situations (static conditions) each chain would carry half of the applied load. However, with all the variables on loading, balance, and other forces involved in an incident where the chains are needed, it doesn't seem prudent to size each chain for just half of the GVWR or whatever design weight is used (more salivating mechanical engineers).

My recommendation is to go big, Sizing each chain and end accouterments for the GVWR is safer than sizing for the tongue weight, unless the salivating mechanical engineers come up with a better plan.

As long as we're discussing chains, is it mandatory (e.g. the law) that the chains be crossed or is it just a suggestion? Do the laws differ from state to state? I know the reason for crossing them but can you get cited if they are not crossed if you are stopped?

AZMike Mike, some state require them to be crossed, I remember Tractor time with Tim (https://www.youtube.com/watch?v=H8Lu177WbzE) they talk about crossing the chain plus putting twist in them. Personally twisting the chain should be a big NO as it increases stress in the links. Crossing, I see advantages and dis advantages. Personally I cannot cross the chains with the Andersen Rapid hitch as the chains will snag the hitch and get stretched damaging possibly both the chain and the hitch.

Here's the pic of the welded loop. 0.443 so guessing it's 7/16 stock if you account for my potential error in measurement.


That welded loop does not seem sufficient. Chain strength, size, link coupler strength, hooks wont matter if that point fails. I once towed a rented diesel air compressor and had a failure of a similar chain loop point where the weld broke free. So I started using an additional segment of chain around an A-frame in the tongue point to supplement these type attach points to serve as an additional chain connect loop point. Its not pretty, but if the welded loop fails, the chain loop can help take over to support the hitch chains as the new anchor attach point. Like having 2 or 4 tie-off rope points rappelling instead of one. Maybe my thinking is overkill but if you have experienced a failure in this area like I have it sticks with you.