Anyone knowledgeable about fifth wheel construction?
A couple of weeks ago I had a major frame failure on my fifth wheel. I posted about it with some pictures a week and a half ago. The main metal beam that goes to the nose cracked. We got that welded up to where it won’t crack again. But when we had torn the inside out to uncover the whole frame around the pin box and the beam that extends back to the main chassis frame, we could not find any way that the side walls of the trailer—the “box” you live in—connected to the frame in the front that supports the pin box and the whole front that extends over the pickup bed. We could find nothing obvious that was broken that would have connected the wall, floor and roof structure to the heavy rigid metal frame that extends to the front. So we surmised after having fixed the frame that the front must slightly float or flex around the metal frame. I have decided that is wrong. My pin box is now rigidly welded up, but the front wall structure can move up and down as I travel independently of the pin box approximately 1 inch. It does effect the inside closet. So I’ve now decided that what might have broken first, before the main frame broke, was whatever attaches the wall structure of the camper to the frame up front. The loss of that additional rigidity that the wall structure would have provided then allowed too much stress on the metal frame. That’s my thinking. So my question: does anyone know for sure that the front section of a fifth wheel is in fact hard connected to its rigid supporting frame, and, if so, how do they connect? I can see how that main body is connected with bolts going up through the outriggers off the main beam and then connecting to the wall structure, but we could find nothing up front. I imagine it varies from fifth wheel to fifth wheel but are there generally accepted ways the front wall structure is connected to the main supporting frame? Anyone know how a fifth wheel is put together up front? Or does anyone know somebody who used to work at Alpenlite that’s still around that would know how they were put together? I’m puzzled.
