On a cycling forum, a member posted this info when I rebuilt the tongue of the trailer, as it turns out he knew what he was talking about.....
He was right on the money with this info, as it was always in the back of my mind, and I checked fairly often for signs of cracks. The other day I found some cracks, which would have led to a catastrophic failure.Originally Posted by bme107
You can see the crack, it extends almost all the way around the tube, and started from the center gusset, yes it acted like a can opener.
I have now taken his suggestion to heart and have fixed the problem, quite possible it is overkill, but I need the trailer to be reliable and stop breaking!
When in doubt as Larry says....
First I welded the crack up, I bent it open a bit and filed it down so I could get it to close all the way, as it was a bit stretched, then I cut out some super mondo gussets, that will cover the whole deal, both sides, from the strong back at the basket of the trailer right up to the parking brake at the hitch.
I welded it all along the top edge and I drilled some holes so I could button hole weld along the bottom edge of the tube. I think this will be rather strong.
Both sides done with some paint on it.
The finished trailer, Version 3.1
This added right around 2Kg to the trailer, bringing it right to 33Kg, but the new weight is on the tongue of the trailer making it feel somewhat heavy, but not a big deal. The first thing I noticed is that the trailer now feeds all the bumps and wiggles back to the bike, I guess the new gusseted tongue is much more rigid than the old one. I now know that the old one flexed a lot, which is what led to it's failure.
With all that I've learned from this trailer, I'd love to build an all new trailer, but that is not in the works for some time to come, maybe next spring, if I can swing it. For sure the next trailer will be built from bicycle CrMo tubing, and I'll get a pipe bending machine to eliminate more welded joints.