Originally Posted by 51phiveoh
I hear ya...I'm not a "by the book" either, at least when it comes to adding/making attachments. Thanks for the pics.
Those arms just attach to the 4x4 tube and not to the frame. The weight of the generator while in tow, and the vibration doesn't put stress on the L welds and the tube like the OP talked about?
Weight is weight and you need to keep an eye on those welds, period. But the force exerted on the bumper can vary greatly depending on your mounting method.
Here were my theories, take them with a grain of salt:
I wanted to spread the load on the bumper as much as possible. Many of the hitch mount shelves only attach to the bumper in one place … putting ALL of the weight and bouncing at that one spot. Many of the hitch modifications use the dual U-bolt connections, which then further restrict that force to two very small points on the bumper structure. The Mount-N-Lock system uses two arms, halving the point loads on the bumper and those connection points are flat top and bottom, spreading the load from two points to a 4” square area at each point (or something like that). (Think of the mark a ladies high heel makes in linoleum vs a men’s dress shoe heel.)
I wanted to keep the weight load close to the bumper. The further the distance from the connection point to the weight load the higher the twisting force on the bumper. Many of the commercially available shelves hold the load almost two feet away from the bumper, my solution holds it inches from the bumper.
I also wanted to keep the load close to the connection between the bumper and the trailer. Again, the larger the distance the larger the effect the load has on the connection. (Think of a wrench with a small handle vs a wrench with a breaker bar … the distance provides more force).
I also opted for the 2kw generator instead of the 3.5kw generator. It operates my little trailer and it’s little air conditioner unit and is half the weight of the 3.5kw that I was initially eyeing.
I’ve had it in service now for two seasons and see no weakness in the welds or twisting in the bumper (ie, my sewer hose goes in and out easily).
Your mileage may vary.
(attached is a clearer picture of the arm itself as I was in the measuring/planning phase.)