Tongue help

[RandyG]

I am kinda stuck right now in my build when comes to the tongue. I made my own frame from .063 alum. with C channel and U channel, it's plenty strong but as far as having a strong enough point to attach a coupler, there are a few ways I have considered but think it's a good idea to get outside eyes in. Sorry for the orientation, the frame was against the wall. The 2 C-channels (black)and the U (redish) run the length of the whole frame. I also need to make the tongue 18" longer. So... ideas?

[CarlLaFong]

I can't make heads or tails out of those pix. Drag the frame outside and take some better ones

[RandyG]

I thought the pics would cause problems, I'll take some more weekend. This has just been on my mind alot.

[angib]

The tongue is a U-section with two sides and a flat top, right? How wide? You can buy couplers for 2.5" and 3" sections.

[RandyG]

Better pics



The U and the space between the Cs is 1 7/8
From edge of C to the other side is 5"
I have a piece of 2" square that can slide over the U but with that alone, I don't trust it.

[RandyG]

So here is what I am leaning towards...
Put a 2 ft piece of tubing over the U
Place another piece on top of that, the final length of the tongue
Cut 2 piece of SS .40 to slide into the C's and extend to the coupler, also be tied in on the sides of both tubings
Rivet and bolt everything together
Make a piece of solid stock Al. to slide into the tube just to give the couple something solid.

I hope this makes some kind of sense. I really think 2 pieces of square tubing will be more than enough but this is one part where overkill is a good thing.

[KCStudly]

Whatever you do needs to tie back into the strength of what you already have. You don't want to concentrate any loads at any one point between what you add and what you already have.

[Ron Dickey]

On the boxkite I have a my tung set up much the same way but it is a full square it was an old boat trailer and broke at the right time and the wrong place. (another story) anyway it broke just about 5 inches away from the trailer. there is a lot of weight there your car goes up and your trailer goes down and then your car goes down and your trailer goes up and you do not think about it you just know it is following you.

I went up it went up I went down it went down I went straight and it stayed down. I thought the coupler had come off. I was just a block form a very fast highway in L.A. Area. When I stopped I got out and walked around it was still connected. It had snapped and was holding on buy just the top part of the hitch.

It was rebuilt latter that day, new pc's added and is now 5 inches shorter in length.

This part is more important then you think and also the cross chains or cables in my case will save you a lot in many ways.

Ron

[RandyG]

Oh I know how important the tongue is and how much stress is put on it. That is why I'm asking everyone i know for advise. My frame is one of a kind, and with that proposes unique challenges.

[pchast]

Randy,

Don't patch the piece together. Adding short tubes and your side bolsters
induces 'hard points' concentrating bending forces. I'm no materials engineer
but I think You need to decide if your material is durable enough to take
the flexing from road forces without breaking.

If not, use full length bracing strong enough to resist all such forces and
resist the damage from bending.

Otherwise:
I have doubts that the U channel will maintain its shape over its expected
service life in that singled up tongue without banding or squaring the material.
It may even require internal gussets to resist losing the square.

[RandyG]

My whole frame is made of an aluminum that rarely cracks, it will bend before it will crack. Not sure if its a good thing...
But yes you are right, the U will not be enough by itself. I will add plate and tubing to the U that will also extend into the spine of the frame.
Hopefully my airframe skills will help me make the right choices. I do have a few more people to ask at work, some have been working on jets longer then Ive been alive.

[KCStudly]

Can you fit a longer length of alum box tube into the center channel and have it extend under the floor a good long way (perhaps to the back of the trailer), rivet that into the channel all along, put anti-crush sleeves in the tip and bolt the coupler to that?

I know hindsight is 20/20, but I'm a little surprised that you did not have this worked out before starting.

There will be a solution, all is not lost, but since you are breaking new ground (in our little world, at least) you may find that folks are a little reluctant to give any kind of hard engineered solution... unfamiliar with particulars of your unit body build method and material schedule.

[RandyG]

Ya know... I thought I did have it all planned out but plans changed for the sake of keeping it all aluminum to rid dissimular metals causing corrosion. I have considered running a tube all the way through, and I spoke with a friend that can machine me a piece of that crush block you speak of. We thought of the same ideas. I'll take that as a sign as that being the top choice.

[angib]

I'm avoiding commenting on your plans, as it's almost impossible to tell in detail what you're planning just from words and the devil is in the detail.

Remember that the maximum bending load on the tongue is right at the front of the trailer's main frame and it gradually reduces to nearly nothing at the coupler. So it's the strength at the back where it meets the Cs that really matters. Adding anything in front of that point, even just 1/4" in front of that point, doesn't add strength.