U bolt ability to resist sliding (is clamping force sufficient)

[jwac50]

I am rebuilding a 3500 GVW utility trailer. I want to replace the trailer tongue and add two cross members to add strength and do not want to have to weld them in place. Tongue is 3x3 box tube .189 wall thickness and so are the two new cross members. I want to use 1/2 inch u bolts and plates to secure the tongue to the new cross members and also u bolts to secure the cross members to the existing trailer frame (3x3 box tube also). Trailer empty weight will be 850 lbs. I do not plan on drilling any holes in the new tongue or cross members. Just want to bolt the elements together with grade 5 u bolts custom mode by a axle and spring shop.

My question is:
are u bolts and plates sufficient to prevent the tongue and/or cross members from slipping when towing the trailer.

thank you john w

 

[JStephen]

I don't know if anyone will be able to give you a good answer on that. On vehicle design in general, apparently a lot of it is based on manufacturer's past experiences rather than just being able to sit at a desk and deduce that a vehicle of XX pounds weight will experience YY pounds force in operation. I'm not aware of a "Trailer Design Code" that addresses strength requirements.

That being said, I would opt for a connection that didn't depend on friction of the parts if possible, so putting bolts through the members rather than around them.
I'm a little hazy on exactly what your geometry is, but you might consider putting flat bar in there instead of square tube.

 

[XR250]

Probably, but still a really bad idea. Take it somewhere and get it welded.

 

[SAIL3]

not a good idea....can vibrate loose overtime....can easily overtighten and crush the tubes...depending on friction is not a dependable method , especially , where impact loading may occur....and many other reasons...

 

[BadgerPE]

Why are you replacing the tongue? Is it damaged? Pictures or sketches may help.