I made a couple of attempts this summer to calculate the forces generated by the WD hitch. It is a very messy calculation, I could not find all the constants I needed (like spring rate of the bars and my truck suspension with Timbrens added), and ultimately it was more trouble than my situation warranted.
We engineers have to be careful about perspective. Measure with a micrometer, mark it with a piece of chalk, and cut it off with an axe. Once in a while it just makes more sense to tack-weld it together and see if it works.
For my own situation and based on many many weigh tickets (I know the guys at the truck stop by name now), I have determined that my own Equalizer hitch redistributes the static tongue weight as follows: 22% to the trailer wheels, 82% to the rear wheels, and -4% to the front truck wheels.
If you find a reasonably simple formula for the WD hitch, let me know.
