Posted by David Sherman on Wednesday, October 18, 2006 at 5:17PM :
In Reply to: Fishplating frames... posted by Jonas on Wednesday, October 18, 2006 at 3:43PM :
My M37 has fishplates on the frame. Not sure how they got there, but I suspect it had something to do with adding an extra gearbox with a chain sprocket under the bed and re-arranging the driveline to the front winch. Somebody may have once had something heavy like a welder or compressor in the back. All the modifications are pretty crude. The telephone truck, on the other hand, also has a fishplated frame, but it was modified by a legitimate company that did a nice job of adding the utility body and assorted extra gearboxes. I suspect that whatever they did with the fishplating was done with the approval of Dodge engineers. I highly doubt that it's welded on, but I'd have to look and see just how it's bolted. Location is everything for holes in a stressed structure. There are always a few spots that end up with almost no stress, based on how the loads are applied. Those are the places where the holes should be. In a simple beam, they're usually near the center of the web, but on a complex shape with loads applied in various spots like a truck frame, the low-stress spots could be in unexpected places. Of course then the fishplate itself would be applying loads to these previously-unstressed spots. To do it right, with heavy loads and minimal steel, takes some serious engineering, preferably finite-element analysis on a computer. On the other hand plenty of old farmers just welded on whatever they had laying around and it worked okay for them.