Trailer Frame Input

[Cloyd99]

Hello everyone! I am in the early stages of designing and building a teardrop camper and am looking for some information on the trailer frame design. A lot of the links in the stickied threads on the forum now appear to be dead so I am digging for info. Most of the trailer designs I am seeing have the frame on two planes (a square frame above with the tongue attaching underneath). I am more inclined to build a trailer with frame and trailer in a single plane, possibly with a full length tongue. I would think it would be stronger.

Here are a couple rough drawings I did on Microsoft Paint that are more along the lines of what I am thinking. They aren't to scale. Has anyone built a trailer with a similar design? I would appreciate any input I can get.

[rjgimp]

I don't have much advice to offer regarding your design but I have discovered many of those old dead links can still be viewed at archive.org also known as the Wayback Machine.

[twisted lines]

look good,
Overkill; 1- 1/2 X ?
Use triangles in corner's Under
Front joint' ; gusset all the angles instead see above.
Stronger method on rear Joint! more area to weld .

Download (Solid edge) instead of Paint
Free easy and tutorial's .

[QueticoBill]

If you put it all in one plane, you have a lot of moment connections. Keeping the "y" and tongue as well as the cross bars unbroken is going to be stronger. Good welding and gusset plates would be almost as strong.

[tony.latham]

Well... It's considerably stronger if you put the tongue under the frame. It eliminates the tendency to pull the frame apart. There was a Facebook post on one of the Teardrop DIY pages last week that had photos of a trailer with cracks where the tongue butted to the frame and if I recall, it had gussets underneath the corners.



Tony

[twisted lines]

A frame under to the second brace with a cap.
My Heavy trailer; outside frame

[Cloyd99]

Thank you everyone for the input!

Well... It's considerably stronger if you put the tongue under the frame. It eliminates the tendency to pull the frame apart. There was a Facebook post on one of the Teardrop DIY pages last week that had photos of a trailer with cracks where the tongue butted to the frame and if I recall, it had gussets underneath the corners.



Tony

Tony, I like your frame design. I have been reading through your build thread and will go that way if it's stronger. I am trying to get a better understanding of the forces at work on a trailer chassis. When you say "pull apart" are you meaning the tongue is trying to come out or the entire thing is trying to scissor? Either way, that's scary. Just for fun I mocked up a better model on Sketchup with a full length tongue. Now that I see it drawn though, it's probably overkill and too heavy. I'd be interested in where the weak points would be on this type of design.

A frame under to the second brace with a cap.
My Heavy trailer; outside frame

What tubing dimensions did you use on your trailer?

[tony.latham]

This design of mine works fine using 2" .120 tubing. You can go 3 x 2" thinner tubing but it's harder to weld. Many-many miles on mine.



With a traditional spring axle, you'd need to add another cross-member with it, and the rear cross-member is fine with 2" .120 angle. Your last sketch looks awful heavy.

Tony

[halfdome, Danny]

I've built 6 teardrops with a frame as you speak of.
I have lots of welded gusset's that I mount the high quality plywood floor to with elevator bolts.
As I see it the floor is an integral part of the frame.
The center member is a 48" hitch receiver to accommodate a removable draw bar/tongue.
I weld angle iron pieces on the rear hitch receiver as it's welded below the frame.
Danny

[twisted lines]

The one pictured was free 1/4" wall 2" x 4" Scrap.
Made a hydraulic dump trailer.

[swoody126]

listen to tony.latham

he's been furthur down these roads than many

utility trailer manufacturers use the under mounted method because they have liability responsibilities and it is stronger

running the framing and tongue on the same plane forces one to cut cross members in 1/2 and butt weld them to your proposed full length tongue

those butt welds aren't as strong as welding 2 pieces one on top of the other ... even with your proposed gussets IMHO

seen too many single plane frame/tongue combinations fail at the point where the frame and tongue meet ... ruins a trip

sw

[working on it]

I have a single-beam tongue on mine, 72" x 3" square tube, .188 thick. It is attached under the plane of the frame, to three cross-members and a central spine (butt-welded inside the frame). The tongue is sistered to the spine, for extra strength and rigidity.

tongue attached to spine.jpg (359.22 KiB) Viewed 339 times

[KCStudly]

Other good reasons that OEMs don't do it that way is because it takes more man hours to set all those miters and ensure that the hitch is centered and equidistant to the tips of the axle stubs while still maintaining proper butt weld joints. Much easier to build the A-frame separately and align it before welding it on with a few much easier fillet welds.

[QueticoBill]

Either flat - in one plane - or not, can work, but pretty sure the flat approach requires more work and materials, thicker at least, and is likely heavier.