15x7' trailer design thread

[tony.latham]

i thought the tongue came as a piece that's inserted into a coupler from tonys specs

It's just a 24" receiver incorporated into the tongue frame. Easy-peasy.

Tony

[drhill]

Easy Peasy Tony and a great idea. If I ever build a second trailer that is something I will include.

When I built mine I knew I would never get the axle in the right place. I have built a boat trailer before and a couple utility trailers. The boat trailer turned out fine. The utility trailers, one was tongue heavy and the other tongue light. With a teardrop I knew there would be too many variables in how it was loaded for me to get it right. So I welded the spring mounts to a couple pieces of 2x2x1/4 angle about 30" long. A couple pieces of smaller angle are welded to these for the fender mounting. The trailer frame basically sits on the 2x2 angle iron pieces and is bolted in place. (horizontal bolts at/near the neutral axis of the trailer frame) I started with it at the 60/40 position and ended up moving it 8" forward for decent balance. I have a heavy tongue box and always at least 2 bikes on the front. If I built another, it would have the same moveable axle system, and a removable tongue.

[iconicflux]

I was using the load calculation tool at https://www.roguefab.com/tube-calculator/ for this to figure out the tube size needed and it looks like I'm going to have to go up in tube size to 3x3 for the main rails.

Tony - I'd love to know if you agree with the tool that a 180" 2x2 with 1000 lbs on it doesn't have enough safety factor (about .5 instead of 1). If I went to a 3x3 it would have a safety factor of almost 1.3 and that would make it easier to do the removable tongue as well so I think that makes sense.

Anyways, I'd love your thinking on it or any knowledge about other ways of calculating the strength needed for 1000 lbs per rail.

Thanks

[John61CT]

That tube calculator is for round profile right?

Rectangular or I-beam is usual for trailers

[iconicflux]

Yeah, there's some other stress calculators around. I think I was actually doing it wrong though.

Based on a trailer the beam span would be the area between the cross bars, right? So if you had cross bars at every 60" then your maximum beam span would be 60" instead of calculating the beam span as the maximum for the whole beam, right?

At the very minimum I have to be calculating the stress wrong because I'm not calculating it based on uniform loading but instead have been calculating it based on deflection given one stress point in the middle.

Ugh this stuff is hard.

That tube calculator is for round profile right?

Rectangular or I-beam is usual for trailers