Improving Trailer Safety Chain Connections

We often joke about safety — Yup, Safety 3rd.  While it’s fun to joke, there are a few things we do get quite serious about.  How to attach trailer safety chains is one.  Today we’re looking at connecting chains on the trailer tongue, so the chain is the right length. But how long should they be?

Instead of guessing on chain length, make them adjustable.  We cover the reasoning and many attachment ideas in the article “How To Attach Safety Chains.”  Then, in today’s article, we’ll look at another solution that is both easy to install, and adjustably permanent.

Yes, there are many levels of “safety”.  From being careful while turning a wrench, to safety that involves people’s lives.  Trailer chains fit the higher category.  So, we will walk the talk by giving you Free Plans for one good way to connect trailer safety chains.  Why not?  It can make things safer.  See the links below.  After all, good safety chains are on the list of Critical Things To Get Right on your trailer.

Adjustable?  Or  Permanent?

What do I mean by “Adjustably Permanent”?  There are ways to attach safety chains that are very adjustable.  One of the best is the Link Lock System which does a great job of making the chains very easily adjustable.  On the other hand, there are attachments that make the chains permanent — like welding chain hangers.  (Please don’t weld chain links.)

Personally, I want a method that acts permanent (from a solid attachment and security perspective), yet is adjustable.  It must be rock solid — as in no room for failure.  I also want a system that is easy to fabricate from common materials.

If you’re like me, it is rare to pull my trailer with a vehicle other than my truck.  So, I rarely need to adjust chain length.  I’m fine with something a little less convenient to adjust (especially if that makes it absolutely solid).  Yet, for the rare times when I do tow with a different vehicle, like a friend borrowing it, I want the ability to adjust chain length.  I call this paradigm “Adjustably Permanent”.

Hmmmm.  A permanent, rock solid, feel when in use, yet adjustable when we need it.  Can we get there?

How To Attach Safety Chains

This is an important issue that doesn’t get a lot of attention generally.  People talk about wheels, about weight distribution hitches, about aerodynamics and ride quality, because they have something to be enthusiastic for.  Safety chains are another matter.  They’re mundane, don’t do much, they’re often in the way, etc..

Crash Did Not Have To Be This Bad
Sometimes the most important things are not the most interesting.  Well, until you suddenly need them !!
I love this photo, and yes, we’ve used it before, because the damage did not have to be this bad.  Properly attach safety chains to minimize possible damage.  Reduce chain length, then things can’t get so out of control.

While most people will never actually “need” the chains, if you ever do, they are suddenly VERY important.  If the install is poor, then they won’t do the job, which can lead to horrible outcomes.  (Like this when the Trailer Came Loose.)  Even if no one is injured or killed, property damage can still be a mess.

The photo here is a great example.  Note that only one chain is still attached.  Notice how long the chains are.  Their length gave the trailer freedom to seriously bash in the rear door.  With proper length chains, the damage would be much less.

The trick to getting chains to function better is actually pretty easy.  We must attach the chains so they are as short as practical.

Over the years, I’ve tried several ways to connect trailer safety chain.  From cool ideas, to weird stuff.  To see some, read the previous article about Adjustability for Trailer Safety Chains.

Anyway, past ideas have all stimulated something easier.  (That’s the way it is with good ideas, there’s almost always something that can make it better.)

The Genesis

Bolts make a great semi-permanent attachment method.  Attaching trailer chain with bolts is a great idea — except chains don’t like to be bolted.

For safety, bolts really need to clamp solid.  Bolts just work better when they clamp tight.  No rattle, no movement, and no tearing in the holes if they suddenly yank into action.  Impact loading is a bad idea for loose bolts.  On the other hand, chains want to be loose to respond in whatever direction the demand comes.  That makes a mismatch in requirements.  (Engineering speak.)

The first good concept to attach chains uses washers to take the space so only one chain link is bolts solid.  This works, but grinding the washers to fit is a pain, then worse, re-stacking the washers to adjust chain length.  OK, good idea, but not good enough.

<Photo of chains with washers>

The next idea is a better approach to the same thing.  Special formed spacers will solve the capturing issues and make it easy for a solid connection.  So, I did the design, and got a quote.  Ouch.  Production cost was too high unless I made 100,000+ parts, which I really don’t want to warehouse.  I was thinking it would be cool to have these for customers, as a give-away, but the price was way too high.  Humph.

Attach Safety Chain With Bolts

Well, back to the drawing board.

A More Elegant Solution

As I considered other ways to use a bolt, I suddenly realized chains can have and probably should have space.  Bolts don’t like to be loose, but chains do, so put the chain in a pipe!  Make the bolts tight, but let the chain be loose around the bolt, inside the pipe.  That makes it completely captured.

Better yet, use a square tube so it can bolt down solid.  The tube takes the bolting forces, while the chain is free on the inside to move as it needs.  The bolts are also more supported in case of an emergency.

Tube Connection

The pipe concept allows us to attach the chains with a bolts, without adding any additional stress to the chain.  I like it.

Analyzing farther, we get 2 bolts, doing the same thing in parallel.  Both bolts go through links of the chain, for redundancy.  Also, a double bolt connection constrains the pipe (or tube) so it won’t twist or pivot.  That works.

This manages the “permanent” side where the chains attach super solid.  Then, to adjust chain length, simply pull the bolts and move the chain before installing the bolts again.  It is not as easy as the Link Lock system, but it can be done quickly, and it’s not hard.  That fits the “Adjustably Permanent” paradigm.

How Does It Perform?

We gave some system evaluation questions for attachment methods in a previous article.  Here is that same evaluation for this “Chain in a Pipe” system.

Does it follow the rules?

  1. Are the chains strong enough?  Yes.  Size the tube for the needed size of the chain.
  2. Will it grind chains on the ground?  No.  Chain length adjustment is easy, so there is no reason for droopy chains.
  3. Does it weaken the chain?  No.  It does not weld to the chain, and it does not bend or damage the chain.  Also, the mounting (with Grade 8 bolts of the max diameter that will fit through the chain) is stronger than the chain.
  4. Is it easy to adjust?  Moderate.  It’s not super easy as it does require tools, but it’s straightforward and simple to do.
  5. Are chain forces in the right direction?  Yes.  Direction of forces are in line with the chain.  (I will note, however, if the tongue dives under the vehicle, the pull is backward, but it’s against the steel tube.  As noted above, chain forces on the bolts remain always in the same general direction.)

Conclusion:  This Concept Works.

So this concept does follow the rules.

Patents to Attach Trailer Safety Chains

With every good idea, there is a strong possibility that someone else has already thought about that.  If they did, and if they filed a patent, then we need to respect their intellectual property.  So, after some experimentation with many ways to adjustably attach trailer safety chains, it’s time to research.  I search the USPTO website.  (United States Patent & Trademark Office).  After some searching, I found a patent for the Link Lock system.  It is kind of similar, so examined it.

As an Engineering Consultant, I am frequently asked by customers to find ways around competitors patents.  I’ve been quite successful at this, and I’ve learned how to read the legalese to understand what is proprietary.  In this case, the approach to attach the trailer safety chains is different than the Link Lock system.  So we are free to build them, and free to show you what we did.

This idea does accomplish many of the same objectives stated by Link Lock, but with some key differences.  First, it is NOT nearly as easy to adjust.  It’s the concept of “Adjustably Permanent”.  Second, it does NOT guide the chain.  Third, the attachment of the chain is the attachment of the tube.  One is not separate from the other.  The tube is only there to hold the bolt clamping load.  The chain through is not part of the attachment.  Finally, this design does NOT require any special parts.  A simple piece of square tube and some grade 8 bolts (both size appropriate for the chain.)

Comparing Ways To Attach Chains

This idea overcomes some of the drawbacks listed in the Link Lock review article, but at the same time, it does NOT do some of the cool things that Link Lock does so well.  It’s a different animal.  The two key differences — 1.  It is not as easily adjustable;  2.  It is made from common materials (no special parts).

The system consists of 3 things (each side).  Chain, Tube, and Bolts.  All are common and easy to get.

Nice features of this system are:

  1. Bolts holding the chain do not pinch the chain.  The chain is free to move.  No extra stress.
  2. Bolts holding the chain are solidly in place.  While the chain is free to move, the bolts are solid.
  3. The bolts are supported on both sides of the chain, giving a strength advantage, like a clevis.

Safety Chain Sizes

One of the big hiccups with this system is the tube size.  Chain only comes in certain sizes, and that’s true of tube also.  Finding the right size tube can become a challenge.  In the case of the chains in the photo above, 1.5″ square tube with 1/8″ wall works well for the smallest chain (3500# trailer).  2″ square tube with 1/4″ wall works well with the large chain (14,000# trailer).  Unfortunately, there is not a convenient tube size that fits the middle chain (10,000# trailer) very well.  That means it will need to be in a tube that’s a little oversized for the chain.  That’s OK, but it is something to note.

System Analysis

This system holds the chain with two bolts.  In reality only one bolt will hold the load if the need arises, so each bolt must be capable of carrying the entire load.  We recommend Grade 8 bolts of the largest size to fit through a link.  That maximizes functional security.  It may be tempting to use Stainless Steel, but make sure you understand stainless and it’s strength before you do.

Comparing this approach to direct bolting, we see some differences.

  1. For a bolt clamping a link, if the chain yanks, it may turn the bolt because the chain is under the bolt head.  If, on the other hand, we attach the chains in a tube, a yank does not change the interaction with the bolt.  The tube directs the chain so it cannot twist the bolt.
  2. In a tube, a yank of the chain does not put a pure bending force on the bolt (like to bend it over).  Especially with 2 bolts.  That makes the chain attachment much stronger.
  3. The chain cannot come loose.  Not even if a link or a bolt bends.  Something must break to un-attach the chains.
  4. If the chains are suddenly in action, pull forces are always in the same direction.  In most other systems, if the tongue dives under the tow car, or veers sideways, forces where chains attach will switch.  They pull back, or sideways, not forward.  In this system, the direction can reverse, but because of the tube, forces at the chain link around the bolt will remain in the same direction.
  5. Does it adjust?  Yes.  It is not as easy or as quick as Link Lock, but it is not complicated, or time consuming.  2 bolts out, adjust, then 2 bolts back in.  Interestingly, because bolting (and especially lock-nuts) take both tools and time, this concept provides greater theft security.

See the plans for more detail.

The Practical Side

Tube size must be appropriate.  Yes, the chain must pass down through the tube, but the tube itself must be strong enough for the forces.  In a straight back situation – like if the breakaway kit kicks in – then the tubes take very little load.  In cases where the tube does take load, it can deflect and deform and it won’t really matter.

If you’re making this an installation on an existing trailer, just bolt the tubes to the trailer frame (because the bolts hold everything).  When building a new trailer, you can weld the tubes to the trailer frame.  That makes the system marginally stronger, but welding is not required to make it work.

As an option to help with adjustments, you can glue the tubes to the trailer frame.  When glued, they stay in place on the frame even when you remove the bolts for adjusting.  Glue won’t help in an emergency, but then the bolts are in, so the glue doesn’t matter.  Glue will just make adjustments easier.

Attach Your Chains With Free Plans

We believe trailer safety chains are really important.  If we can help save one life, or help avoid one injury, or reduce the cost of a mishap, we’re in.  So, we will walk the talk, and give these ideas for free.  They are yours.  See the Free Plans here.

There are some things to figure out as you approach this.  The plans are simple, and they are generic.  Rather than trying to fit chains from every manufacturer, these plans show where to measure the chains for the dimensions and how to figure out the bolts and tube.

Even More Ideas

Yes, more ideas to attach safety chains . . .  We won’t go into much detail, but have a look at the images, then I’m sure you can figure out how to build them.  These are a couple other ways we’ve done safety chains for customers over the years.

First is a system with a single anchor bolt each side.  The keys to successfully implementing this system are 1) alignment; and 2) good welds.

Single Bolt Adjustment

Second is a similar system with bolting redundancy.  Keys to success with this system are the same as above.  To get bolt spacing correct, use the calculations for the 2 bolt tube system above, shown on the page with the free plans.

Twin Bolts to Attach Chains

A note about bolt orientation.  One of our rules, #2, Will it grind chains on the ground?  It is easy to see that the bolts in these 2 images are below the bottom of the tongue tube.  That leaves a point to snag.  While it does not directly abraid the chain, it’s not the best situation.  For convenience we’d like the bolt heads on top to avoid snags of cloths or flesh when dealing with the trailer.  So, how do we resolve it?  Or is it a problem worth worrying about?

On my trailers, I weld a bent arc, usually 1/4″ x 1″ or 1.5″ looping down an inch or so under the tongue as a “skid plate”.  I’ve never had a tongue come off where it needed to act as a skid, but it helps in awkward situations where the hitch or tongue hit the ground.  (Sometimes off-road, or on steep driveways.)  You can place the bolts facing up as in the featured image at the top of the article, and/or add a skid plate.  It’s a niggly thing, but worth noting.

Good Luck As You Attach Your Chains.

Thank you for taking the time to read.  We hope you will adjust your chains short and solid for increased safety.  Chain length is a big factor in how serious an accident can be.


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