[wingnut60]

In reference to the strength of the king pins on a Mobile Suites trailer, let me pass on the results of an experiment I tried, which failed miserably:

Unit #1869, 36TK3, factory extended pin mount (Lippert)

When I got this trailer in February, I was bound and determined to use a gooseneck adapter to pull it. Against the advice of everyone who I talked with, I installed a B&W gooseneck hitch and got an adapter rated at 20,000lbs. I wanted to not have to deal with a bed hitch--leaving the adapter on the trailer was a very appealing idea. I did everything the adapter company said to do, including bolting the adapter to the king pin plate. So, if you can picture this--a very clean looking installation, and I was ready to head out with my very heavy trailer connected to my truck with the goosenect ball and adapter. Hooking up was so easy, why doesn't everyone else do this? I was pulling out of the back yard and I have to make a sharp turn into the street--the breakaway cable got in a bind and pulled the pin, locking the brakes. The ground was soft, and the dragging wheels began pushing up sod. Finally, the trailer quit moving, but I really didn't notice the drag and just kept pulling. Suddenly, a loud KA-POW! I stopped pulling and looked at the adapter/hitch box, which were bent at a terrible angle. Getting out to assess what had happened: when I kept pulling the dead weight, stress on the hitch pin plate was too much, and the KING PIN JUST PULLED OUT OF THE WELD. Would this have held in the highway situation you just described--no way. The forces I put on the king pin could not have been more than what would happen if the trailer tried to turn over--take the truck with it, maybe, but the pin/plate would not have survived in one piece. This was the factory provided extended pin box. I backed up some--this put the adapter/pin in a less of an angle--and lifted the trailer off the bed ball. Lesson learned.

Happily, I had a Mor-Ryde extended pin box that I got in the trailer deal; three hard hours later, I was on the road with the new pin box and the B&W companion hitch. And the adapter survived without a scratch and the company refunded my money.

I don't know about any other king pins and boxes, but there is no way this factory setup would have held together in a rollover.