Generator Mount Structural Failure
Another structural failure that we suffered was that of the generator platform. It was bending under the weight of the generator. The platform started out level, but when we returned to Vancouver after the main body mounts failed, we noticed that the outboard edge was now 1.5” lower than the inboard edge. (The platform was not bent from the body mount failure, as the box flopped to the opposite side.) You can see in the photo to the left that the front face of the generator is no longer parallel to the enclosure angle attached to the drop step.
The actual deflection turned out to be where the back wall of the platform is welded to the three 4” x 6” tube standoffs. Those tubes were used to shim the platform out from the frame in order to miss the truck suspension. The reason why the deflection took place was because the standoff tubes didn't go all the way to the bottom. They stopped about half way down. And because they were inset about four inches from the side walls of the platform, there was no gusseting effect to deflect the forces. The entire 450 pounds of the generator was relying on the bend resistance of a piece of 3/16” steel plate.
With 450 pounds bouncing on the end of a two foot lever, that bend resistance wasn’t enough. The rear wall of the generator platform deformed around the bottom of the standoff tubes. The whole platform could be bounced up and down by almost an inch simply by me pushing down on the generator with my hands. It’s easy to imagine what was happening when the truck was going over rough patches of highway, and that 450 pound generator was being tossed about.
In order to fix it, we had to jack the platform up enough to reverse the bend damage to the back wall of the mount, so it would sit level again. We then had to get three additional pieces of 4” x 6” structural steel tube, each about a foot long, and weld them to the bottom of the existing tubes, and then to the platform itself. But because the tubes were inset from the corners of the platform, we had to add additional outriggers to transfer the force out to the side walls of the platform to provide the gussets.
The cost, time and effort for this repair had to be incurred. If it wasn’t, the result would be similar to the body mounts once the metal fatigue set in. I wonder what the outcome would be if a 450 pound generator fell off the truck while driving down the highway at 100kph?
