End-of-Days Trailer Build

[HesterFab]

ntsqd, I only went with the 4-link cause that's what i've built before on my crawlers. I really was considering a 3-link but I just went with what I've done before.....Maybe the next one i'll 3-link

I totally agree with what you're saying on the frame rails/strength thing. I only made them at the same plane like I did because if you put them below the main rails like that, you are asking a lot out of the welds that connect the tongue piece to the main rails since they are going to be eccentrically loaded. 2) I think it looks cleaner and 3) because I had some concern of ground clearance. In hind sight, reasons 2 & 3 are super lame, and obviously reason #1 isn't that big of an issue since a lot of trailers are built like that. And besides in my design I have a welded splice pretty close to the area of the highest bending moment!!!!

One thing that I could easily do to make the rails stronger at the point of highest bending stress would be to add a doubler plate to the bottom of the tube. Maybe something similar to what I did for the doubler plates across the splice.


Thanks for the link on the book. I have a degree in civil engineering so I've got the shear/moment diagram thing down.....but I could definitely use some knowledge on actual trailer design. ....bridges are different than trailers

 

[ntsqd]

No they aren't, it's just the members and the stresses that are different. Can do it all in Statics, no Dynamics really needed- hopefully no one is driving across the bloody thing!

Biggest issue is that there effectively is a hinge at the front cross member, going under places the rear welds of the diagonals in tension and the welds under the cross member in compression - which really means that they're along for the ride. With the diagonal intersection the weld bead length increases dramatically, so the weld stress goes down proportionately.
But like I said plenty have done it that way and I haven't seen reports of failures. There was a tongue failure pic on Expi at one time, but I dimly recall that was more due to poor sectional choice than a bad design.

 

[croozy]

All I can say is, I love the fab work already. Watching this thread for ideas on my own 40 style trailer.

 

[JTJeepin]

I have been watching this build and continue to learn from all of you on what i want in an EXPO trailer. Is there any updates to the build.....