Building A Better Folding Trailer Tongue

Intrigued by the cool potential of saving storage space, increased security, and removal of a shin knocker to step over, this new folding trailer tongue adds greater utility to a trailer. This is part of the continuing story of design, and DIY building.  To get the full picture, start with this post on the Economics of DIY projects.

3 Drivers For A Hinged Tongue:

1. When you store a trailer, the tongue length adds a lot to storage needs.  A 5×8 Utility Trailer, for instance, requires about 4 extra feet to store because of the tongue.  With a folding trailer tongue, it takes an extra 6 inches instead!  That saves a lot of space!  For this particular trailer, the tongue is even longer, so the benefit is bigger.
2. How do you secure a trailer?  There are a ton of products from cheap to expensive.  One guy told me, just buy good insurance, because nothing is fool-proof.  Well, I agree, and the real issue is most systems are additive — meaning you add a lock or chain or other feature.  Most of these can be defeated with the right hammer or pry bar or saw and a little time.  Yet, What If . . . we made it subtractive instead?  It’s not fool-proof, but it creates an element of uncommon inconvenience — perhaps enough to thwart a thief.
3. OK, this is a little egocentric, but I like things that are a little different and unique.  I also like to improve on ideas I’ve seen, or invent something new to accomplish a task.

Given these 3 drivers above, a folding trailer tongue is a good idea.  Store the trailer in less space, take the special bolts with you (security), and it’s pretty unique.

The Folding Trailer Tongue

The concept is a tongue that hinges vertically instead of horizontally (like this previous product).  The tongue then folds all the way over to lay on top of the bed for storage.  In this case, we’ve incorporated a really long tongue for stability experimentation, for long material handling, as well as to prove the hinge concept.

In proving the concept, there is one special consideration.  A longer tongue definitely gives more stress and higher forces at the hinge point.  The new design must handle that.

Trailer Tongue in the Extended Position:

Folding Trailer Tongue Hinged Back Onto The Trailer Bed:

The folding trailer tongue is accomplished by manufacturing a few simple parts.  The parts are flat, laser cut (or water jet) then welded with the tongue tube.  Bolts hold it all together.  Four steel tubes are also welded on.

For security, I chose long bolts that are not very common.  They also require some wrenching.  For this design, the bolts are high stress members so if someone tried to use a rope or something instead, it would probably break.  Yeah, it’s not totally secure, but it’s probably enough to frustrate an opportunistic thief.  If not, there’s insurance.

Parts for the folding trailer tongue are show in the images above (green), and in silhouettes (gray).  Then, the assembly ready welding is in the photo below.

Why Do They Look So Funny?

This question is for the Engineer.  First, They are tall because the trailer tongue must fold up and over the front frame member.  That means the hinge point must be well above the top of the tongue tube.

The “pointy thing” is to allow welding in areas of the tongue beam that are less stressed — basically, the mid section.  Third, the notches let parts interlock, and align properly.  That makes for easier construction.  Finally, the small holes are for bolts, and the larger holes are for weld access.

Synthesis did the design with CAD and validation with Finite Element Analysis.  It’s good for a 5000# trailer load — even with that really long tongue!

Fabricating

Putting it all together was a little tricky as you really have to hold all the parts together, in place, at the same time.  Good thing there are a lot of various C-Clamps!

To make things align, the bolts are in place through the steel tubes and tight to hold things for welding.

Note:  Extra bolts hold things for welding, because the heat of welding changes the temper of the bolts.  For actual trailer use, we install new bolts.

Another little trick . . . a thin piece of sheet metal inserts at the joint prior to clamping.  That acts as:  1) a shield to keep weld from going over the boundary; and  2) as a stop to be sure all the parts meet at the same plane.  You can see the sheet metal in the clamping photo if you look carefully.  It’s also in the video below.

As with building a trailer frame, everything is carefully tacked together, then full welds are progressively done later.

Finalizing The Build

For a description of how this all finishes up, enjoy this video.  It explains a lot about setting up for welding as well as final fitment so it all works properly.

Some Things We Learned

One interesting thing we learned is the powder coating extends into the holes more than expected.  Because we want a tight-ish fit, we had to drill them out again.

Another point:  You Must Protect The Wires!  It’s really easy to forget to carefully tuck the wires up into the tongue tube as you extend the tongue.  I had to replace the first wire I put in there because I wasn’t careful.  These images don’t show it, but they’ll have flexible conduit soon.

More . . .

If you want to build one of these for yourself, please let us know.  If there is enough interest, then we’ll make plans available for download.  Just so you know, it takes some time to format plans and write instructions.   However, if you want it, I’ll take the time to do it.

Next up is the how and why of the unique twin torsion suspension for this trailer.  Or read more about tongue length.

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