Is that trailer tongue OK?
- Thread starter e9999
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ntsqd
technerd
Even if it does run back to the next crossmember I'd cut it out and replace it with a tube that runs under both crossmembers. But that's just me having read up on proper design of trailer tongues.any last comments before I buy the dang thing? finally heard back from seller again, took a while, like 2 years...
I like the idea of running another tube inside the tongue, elegant and simple...
- Thread starter
- #23
now, I -being not so proficient on the proper design of trailer tongues- would love to learn why under is better than having the crossmembers welded around the tongue tube as they presently are. Care to elaborate a bit?
Especially now that I bought the dang thing...
I have the same tongue design on my trailer. I found "The requirements for small trailers by the Australian Government" helpful and used it.
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- #25
that doc looks very useful indeed, thanks. Gotta try to figure out the thickness of my tube. Unfortunately, can't see that at the ends as it was boxed in at both ends. I may drill a tiny hole in some unstressed part and try to measure it that way.
ntsqd
technerd
The front cross-member is the highest stress zone of the whole trailer. You want that tube to be continuous. The tongue tube(s) also want to be continuous. Obviously they both can't be continuous and in the same place. Putting it/them under the front cross-member changes the joint from being a "hinge", due to the discontinuity, to being a simple bending moment. All of the U.S. 1/4t mil trailers that I've seen or seen pics of have their tongues built this way. None of the tongue failure pics that I've seen showed a mid-span failure, they all failed at the front cross-member or at the coupler. Note the famous pic in Phil's link.
Tongues are frequently done like what you have and they seem to work in lightly loaded applications, but it's tempting fate the way most of them that I've seen were built. My TrailBlazer's new frame was built like that (came to me that way), but the 2.5" x .25" wall tongue tube runs the full length of the trailer (it's actually a socket receiver at both ends) and the trailer loaded with camp gear probably can't exceed 1200 lbs. Loaded for a weekend my carb'd Xcab Mini easily pulls it and my small block '91 Sub never knew or cared that it was there. That tube isn't the only one though, the frame is what the link above labels a "Composite tongue." If you can find a copy of M. M. Smith's "Trailers: How to Design & Build, vol. 2" buy it.
Tongues are frequently done like what you have and they seem to work in lightly loaded applications, but it's tempting fate the way most of them that I've seen were built. My TrailBlazer's new frame was built like that (came to me that way), but the 2.5" x .25" wall tongue tube runs the full length of the trailer (it's actually a socket receiver at both ends) and the trailer loaded with camp gear probably can't exceed 1200 lbs. Loaded for a weekend my carb'd Xcab Mini easily pulls it and my small block '91 Sub never knew or cared that it was there. That tube isn't the only one though, the frame is what the link above labels a "Composite tongue." If you can find a copy of M. M. Smith's "Trailers: How to Design & Build, vol. 2" buy it.
Here my uncommon tongue design. Not the norm but much stronger then the original.
ntsqd
technerd
I forgot that you too have a TrailBlazer trailer. Yeah, from what I've seen of the stock tongue on these an upgrade is highly desirable.
- Thread starter
- #29
Thanks
Dexter torsion axle rated at 600-1000lbs. Torsion is progressive with 2.5" of up travel(same as a 100 series
) and a wet weight of 600lbs I dont think I will every use what I have. Spent a good amount of time on the trail with several different types of expo trailers prior to my build. I subscribe to Chris of Campa USA trailers theory that trailer wheel travel is over rated. Never seen/heard of a Campa trailer on its side not so true with the other popular trailer manufactures with fancy travel suspension. Most trailers with active suspension tend to load up when they hit a bump and don't have the rebound damping to control it and over they go.
With C rated tires, low air pressure, high tongue, low COG, and light weight my trailer rides well and stays on the ground.
Have you checked you tongue design with the AUS book yet?
- Thread starter
- #31
Thanks
Dexter torsion axle rated at 600-1000lbs. Torsion is progressive with 2.5" of up travel(same as a 100 series
Spent a good amount of time on the trail with several different types of expo trailers prior to my build. I subscribe to Chris of Campa USA trailers theory that trailer wheel travel is over rated. Never seen/heard of a Campa trailer on its side not so true with the other popular trailer manufactures with fancy travel suspension. Most trailers with active suspension tend to load up when they hit a bump and don't have the rebound damping to control it and over they go.
With C rated tires, low air pressure, high tongue, low COG, and light weight my trailer rides well and stays on the ground.
Have you checked you tongue design with the AUS book yet?
good to know
no, not yet figured out the thickness
is there some sort of standard square or rect tubing (or -better-U channel) out there that has a 2" ID? If so I could just slip it on top (outside) the current tongue, that would be easy enough and would make a big difference I would think. I'm not worried one bit about the tube under the trailer or the crossmembers, just the cantilevered tongue, possibly.
The weak point would be were the tongue contacts the box, my guess. With that said sleeving the would help but an angle brace up, similar to my down brace would give strength in both up/down and side to side. Keeping the ability to 90° the trailer is huge IMO. My set up is 27' long and I can turn around in a 28' wide road.
- Thread starter
- #33
I think you're right about the stressed point. For that the inner sleeve would be easier to do than an outer one in my case. May need to open up that tube ends... although if the inner corners are rounded that would be a problem for fit.
Or maybe a short 45deg side brace close to the bed would help and not impair jackknifing too much.
Doesn't seem like a brace above or below the tongue would help much with side to side stress compared to a side brace, though.
ntsqd
technerd
Your biggest load will be in the vertical direction, mostly down and with the highest stress right at that front cross-member. Makes sense to be stronger in that plane than in the horizontal plane. Sleeving the existing tongue will gain a little strength at the expense of more weight. Emphasis on "little" and "more" in that order. Adding a second tube of the same size to the top or bottom will gain you a lot more for the same weight.
Or you could truss it; add a short piece of the same size square tube to the bottom of the tongue right at the front cross member, then run a piece of the same width strap (say 1/8" thick) from one end of the tongue - under the bottom of the stand-off tube - and then to the other end of the tongue. Pull it tight under the stand-off tube and make that pair of welds at the second end start at the very end and progress towards the opposite end. Finally weld the strap to the stand-off. Do this right and the welding induced shrinkage will further tighten the strap. How long to make that stand-off tube is a balancing act between desired strength and how low you can tolerate it going. I'd say 6"-8" is the longest that you'd need, dial it back from there as appropriate.
Or you could truss it; add a short piece of the same size square tube to the bottom of the tongue right at the front cross member, then run a piece of the same width strap (say 1/8" thick) from one end of the tongue - under the bottom of the stand-off tube - and then to the other end of the tongue. Pull it tight under the stand-off tube and make that pair of welds at the second end start at the very end and progress towards the opposite end. Finally weld the strap to the stand-off. Do this right and the welding induced shrinkage will further tighten the strap. How long to make that stand-off tube is a balancing act between desired strength and how low you can tolerate it going. I'd say 6"-8" is the longest that you'd need, dial it back from there as appropriate.
