Safety chain dependability

[CharlesinGA]

Chains should have a BREAKING strength at least equal to the gross weight of the trailer. You should use G70 rated chain. Generally 5/16 inch G70 is rated at 4700 lbs working load and breaking strength is at least THREE times that amount (actually 18,800 lbs). If you have a really heavy trailer, you might need 3/8 chain. which has a 6,600 lb working load limit and a breaking strength of 26,400 lbs. G70 chain is marked every foot in the 5/16 and 3/8 sizes, stamped into the link.

One word of caution, you do NOT want short link chain (thats for load binding) you want standard length link chain.

From the Federal Motor Carrier Safety Administration...... When two safety chains are used, must the ultimate combined breaking strength of each chain be equal to the gross weight of the towed vehicle(s) or would the requirements be met if the combined breaking strength of the two chains is equal to the gross weight of the towed vehicle(s)?
Guidance: If the ultimate combined breaking strength of the two chains is equal to the gross weight of the towed vehicle(s), the requirements of §393.70(d) are satisfied. It should be noted that some States may have more stringent requirements for safety chains.

For Hooks, you want open hooks which are know as "slip hooks" with latches, you do not want "grab" hooks that have a rather narrow slot designed to grab a link of chain (for load binding). The hooks need to have clips on them to prevent them from becoming disconnected. The hooks also need to be G70 rated. https://www.thetrailershoppe.com/pro...ok-truck-hitch

The chain shown in post #10 is, that I know for sure, marketed by Curt. I'm sure it can be found elsewhere. Bigfoot uses these chains and one hook has the clip removed and welded to the trailer frame, I'm having issues with the way this is done, but that's another discussion.

Do not twist chains to shorten them, it greatly weakens the chain in the event of stress on it. https://mechanicalelements.com/twisting-safety-chains/ and a video, https://youtu.be/clj42no4DxY

If you need to shorten the chain, what I did is use a double clevis that is G70 rated at least equal to the chain, https://www.thetrailershoppe.com/pro...roved-4700-wll

If the trailer is used on multiple vehicles with different hitch setups and you don't know how long the chains need to be at any given time, you can install the LinkLock system (welded on) that allows you to adjust the length of the chain as needed in a moment. https://www.linklock.net/

ABSOLUTELY do not use the screw links (known as quick links) as they have very low breaking strengths. An example is one I found that is 5/16 and has a safe working load of 2500 lbs, half that of the G70 chain and hooks, and that was the highest I found. https://www.lowes.com/pd/National-Ha...eel/1002254232



For the receiver cross pin, I bought a locking one from Bolt. They make locks that allow you to use your ignition key on many different vehicles. https://www.boltlock.com/

Video https://youtu.be/-Lq6_N5K1L4

References:
RVIA (Recreational Vehicle Institute of America) PDF file of state by state requirements on the use of safety chains https://www.rvia.org/system/files/me...equirement.pdf
https://lacledechain.com/blog/traile...n-quick-facts/
https://fifthwheelst.com/how-to-prop...l-trailer.html
https://www.peerlesschain.com/produc...e-Clevis-Link/
https://www.linklock.net/wp-content/...hite-Paper.PDF
Google search for Trailer Chain Double Clevis https://www.google.com/search?q=trai...+double+clevis
Google search for G70 raated trailer safety chain hooks with latch
https://www.google.com/search?q=trai...with+latch+G70 Note: DO NOT use what is called a "Grab Hook" that has a narrow slot for the throat, you need a "Slip Hook" which has an open throat.

[Raz]

Originally Posted by CharlesinGA

ABSOLUTELY do not use the screw links (known as quick links) as they have very low breaking strengths. An example is one I found that is 5/16 and has a safe working load of 2500 lbs, half that of the G70 chain and hooks, and that was the highest I found. https://www.lowes.com/pd/National-Ha...eel/1002254232

My Trillium weighs 1800 lb wet with a 2200 lb axle. So the ones you reference would work fine for me. After reading Dave Fish post #4 where the S hooks straightened out, I'll stick to my threaded links. Etrailer sells them specifically for towing with higher ratings. That said, all this stuff is made overseas so unless you have the setup to do your own testing who knows what the real rating is on any of these.

[Geronimo John]

[QUOTE=Raz;810556] I went for threaded links. While they are no way as convenient as a hook, they certainly will not straighten out.

Raz: These type of hooks certainly WILL straighten out.... it is just a matter of at what load they will fail. Typically people buy connection hardware the same size as their chains. Bad idea.

As suggested above, ALL connection hardware should have a working load rating well above that of the chains being used. Some assume that just buying connectors one size higher than the chain is a good rule of thumb. Personally I prefer a different approach as the quality of the hardware can make a huge difference in it's strength.

Better would be to check the rated working strength of the chain and buy connection hardware that well exceeds that number. For example, commercial truckers are required to use the Gold Standard for chains. This is the "Grade 70 Yellow Chromate Transport" series.

For RV towing, each chain should have a working strength that is greater than the weight of the trailer. For my 6,000 pound fiberglass trailer, that would mean I should use at least 3/8" chain that meets the Transport specification. My connection hook needs to exceed this chain's 6,600 pound working load.

Typically Grade 70 Clevis Slip Hooks for transport are rated as:

3/8" Size is 5,250 pounds working load
1/2" Size is 9,000 pounds working load

So to be safe, the 1/2" size is the go to connector for the weight of my trailer. In this case, for this manufacturer's product, using the Transport specification, the one size larger rule of thumb works. But for lesser quality connectors it does not always work out that way.

So, PLEASE check the working loads and go stronger for your connection hardware. Also verify that your chain sizes are such that one chain can handle the weight of your trailer. Having two chains of course gives you additional safety when things go badly.

(As the Airstream owner in Idaho found out:

https://www.airforums.com/forums/f23...lp-220442.html

https://www.jaycoowners.com/forums/f...way-85020.html

Geronimo John

[DJD]

Originally Posted by CPW

If I were to replace safety chains on a trailer, I would replace the chains with coiled cables, sold online by Amazon or places like eTrailer. They are a lot neater and because the cables are vinyl coated, do not clank around like chains.

I second the cables idea! I used a pair with safety chains for about six years before they began to rust a little. I replaced those with new ones a couple years ago and use the old ones around the place when I need to wrap around a tree and put a pull on it when I need to drop a tree into a certain spot. (The coiled cable stays where you put it).
Also Geronimo is giving good advice. I use only forged hooks rated at 5000 lbs, and remember that each chain should be rated high enough to handle the entire load. Crossing the chains a couple times provides a cradle for the trailer tongue but there’s not much chance (think sway) that the two sides will equally share the load in a calamity.

[Peder_y2k]

Safety chain strength is seriously degraded by being dragged on pavement. Examine the lowest hanging links for worn flat spots. If found, replace chain.

[pedalmike]

March 15th, 2021 in Idaho, A couple towing a travel trailer with a Ford Super Duty Pickup lost control of the tow vehicle. It went over the side of the bridge. The only reason the truck didn't plunge into the gorge below was the safety chains that kept it connected to the trailer! I'd like to know what their chain setup was...it saved their lives

https://jalopnik.com/couple-inside-f...bri-1846493605

[Shazbat Sandy]

Similar thing happened to me. Good news was I was going UP a big hill.

[Raz]

Originally Posted by Geronimo John

Raz: These type of hooks certainly WILL straighten out.... it is just a matter of at what load they will fail. Typically people buy connection hardware the same size as their chains. Bad idea.

Obviously, any option can fail. Given the fact that I had safety chains with no way to attach them to the tow vehicle, I chose what I consider the more robust solution. Grade 70 clevis hooks were not one of my options. Just as well as attaching them to the chain would have been problematic anyway.

Originally Posted by Geronimo John

As suggested above, ALL connection hardware should have a working load rating well above that of the chains being used. Some assume that just buying connectors one size higher than the chain is a good rule of thumb. Personally I prefer a different approach as the quality of the hardware can make a huge difference in it's strength.

Better would be to check the rated working strength of the chain and buy connection hardware that well exceeds that number.

Unfortunately most folks, myself included, don't know what the rating is for the chain attached to their trailer as the trailer manufacturer made that choice for us. What we do know or can easily find out is the weight of our trailer or at the very least the axle capacity. That's what I used. Now I can ONLY hope that the hardware I bought actually meets the advertised rating and was not part of the lot that didn't meet the specifications of the buyer and was sold to a third party by the manufacturer to cut his losses.


Now, just to stir the pot, in a previous post there is a picture of chains attached using a bolt and a washer. Is that more likely to fail than welding? Or can the heat from welding change the ratings of the welded link?

[WDavidG]

Originally Posted by Raz

Now, just to stir the pot, in a previous post there is a picture of chains attached using a bolt and a washer. Is that more likely to fail than welding? Or can the heat from welding change the ratings of the welded link?

And to stir it a bit more: Scamp fastens both chains to the tongue with a single bolt. I've not done anything about modifying mine, but wonder about the engineering wisdom of connecting two safety chains with a single point of potential failure.

[AlanKilian]

I don't know if it's right, but I run one end of the chain UP through the frame, over the top to the tow vehicle and the other one DOWN to the tow vehicle.

I figure that way if the trailer comes loose and the bolt breaks the chain is still passing through the frame and will hold the trailer.

They may be sparks and damage, but it won't come loose without actually breaking the chain.

I'm all ears for expert advice.

[Raz]

Originally Posted by WDavidG

And to stir it a bit more: Scamp fastens both chains to the tongue with a single bolt. I've not done anything about modifying mine, but wonder about the engineering wisdom of connecting two safety chains with a single point of potential failure.

And what grade is the bolt?

[WDavidG]

Originally Posted by Raz

And what grade is the bolt?

Key question of course Raz, and I don't know the answer. Would the grade be stamped on it? Even if an adequate grade bolt however I think the tensile and shear specs for a graded bolt assume an application with a specified standard hole clearance. Bolting through a link of chain isn't remotely close to a "standard" hole profile. It appears that this configuration will allow the bolt to bend, perhaps substantially, when under the load of an unhitch situation.

Having said that, I don't have the engineering knowledge to judge whether Scamp's arrangement is "good enough". It certainly looks a bit sketchy.

For all the years I've owned the scamp I've put my concern aside and assumed (maybe just hoped) it must be safe. But this thread has led me to reconsider the safety chain arrangement.

[AlanKilian]

Here in the Commonwealth of Massachusetts, from the way I read it, my Scamp chains do not meet state regulations.

"Each chain with its means of attachment shall be entirely independent of the other chain or of the coupling and shall have an ultimate strength at least equal to the gross weight of the trailer and its load.” 540 Mass. Reg. 22.10"

That sounds to me like I cannot use one chain either looped through the neck, or bolted to the neck through one link.

When I have the axle welded on, I'm going to have them weld on two plates with holes in them so I can attach two separate chains.

Ref: https://casetext.com/regulation/code...wing-a-trailer

[Raz]

Usually bolt grade is indicated by marks in the head. As I recall grade 5 has 3 marks and grade 8 has 5 marks. FWIW I know of at least one person who had their Scamp come off the ball and the chains held.

[Glenn Baglo]

Originally Posted by Raz

FWIW I know of at least one person who had their Scamp come off the ball and the chains held.

Which begs the question, "how many people are there, with Scamps, that you don't know"?

[WDavidG]

Even though their ultimate goal is to sell us their product, this paper has a lot of very interesting data and information on both the legal and engineering aspects of safety chains/cables.

https://www.linklock.net/wp-content/...hite-Paper.pdf

[CharlesinGA]

Originally Posted by WDavidG

Even though their ultimate goal is to sell us their product, this paper has a lot of very interesting data and information on both the legal and engineering aspects of safety chains/cables.

https://www.linklock.net/wp-content/...hite-Paper.pdf

I included that link in my post above. I don't think they are trying to sell you their product. i think the white paper came first, as a result of their conducting several trailer separation accidents (with at least one fatal). I actually like the product enough that I will eventually buy the parts (reasonably priced) and have them installed by a certified welder (I am not a competent welder). I do not trust the installation of the chains on my Bigfoot 25B21RB. I don't consider it as much BF's fault as BAL who I believe is the chassis/frame builder.

Charles

[Raz]

7David, thanks for posting the article. I think you are correct in that this is a sales pitch. The article focuses primarily on chain and chain length with chain attachment secondary at best. Other than heat reducing chain strength, welding vs bolts is not discussed. Also other than strength, the types of hooks is not discussed. The authors, all three are professional engineers, work for Alpine Engineering (PE licenses are state issued and require significant tests). Link Locks contact info, Alpine, Utah. That said, it is an interesting article with lots of useful information. I do have to wonder if there is a trailer on the road that is legal in all 50 states.

Finally, there's this picture. Atleast chain drag won't be a problem.

[Villen]

"ABSOLUTELY do not use the screw links (known as quick links) as they have very low breaking strengths. An example is one I found that is 5/16 and has a safe working load of 2500 lbs, half that of the G70 chain and hooks, and that was the highest I found. https://www.lowes.com/pd/National-Ha...eel/1002254232"




Lesson 1: Do not buy rigging hardware from Lowe's
Lesson 2: Not everything you read is true and accurate


I went to my rigging box and pulled out a 5/16 quicklink made out of 316 stainless with a SWL (Safe Working Load) of 2500lbs. That gives it a minimum breaking load of 10,000lbs (Unless you buy it from Lowe's. Their supplier belongs to the club that calculates SWL as 1/3 of breaking load, not 1/4 Perfectly legal, just not Kosher) My quicklink will hold your 2500lb trailer, plus the shock factor, if any, by itself, So aren't you using 2 of them? If you want a bit more security, Sea Dog sell 304 stainless quicklink #153008-1 through boat dealers and people like West Marine that have a slightly higher capacity of 3000lb SWL and 12000lb breaking strength. Their 3/8 quicklink #153010-1 has a 4900lb SWL and 19800lb breaking strength.

Now this is a bit of a bore to have to screw this thing on and off. the answer is to use your quicklink to attach a 1/2" Green Pin hook https://daubnerusa.com/product/cse-g...en-1677-2-gr8/
This hook has SWL of 5.4 metric tons which is 11880lbs. It can singlehandedly hang your entire FG trailer with your entire family and full tanks. You could go smaller and cheaper, say 3/8?

Two of these and Bob's your uncle!

[Villen]

Originally Posted by WDavidG

And to stir it a bit more: Scamp fastens both chains to the tongue with a single bolt. I've not done anything about modifying mine, but wonder about the engineering wisdom of connecting two safety chains with a single point of potential failure.

Looking at the picture I see one chain with a bolt thru one link downgrading the installation to the strength of one chain. The chain on the left could be an owner with brains did not like the original installation and added a separate chain? That chain looks newer but who knows. Might be better quality galvanizing. I would like to see the specs on OEM safety chain, but mostly I just trade them out with a grade I figure the trailer needs. You'd be surprised what a certain 12,500lb GVWR dump trailer called safety chains.