TundraTower wrote:
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.
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.
Estimating load transfer via a WDH doesn't get any simpler than the following.
Let:
F1 =
combined downward force exerted on A-frame at WDH lift brackets
F2 = downward load added to TT axles
d1 = distance from ball to WDH lift brackets
d2 = distance from ball to axles' midpoint.
Then:
F2 = F1*d1/d2
Let:
d3 = TV wheelbase
d4 = distance from TV's rear axle to TT axles' midpoint
Then:
F3 = load added to TV's front axle = F2*d4/d3
F4 = load removed from TV's rear axle = F2*(d3+d4)/d3
For example:
If your tongue weight causes 500# to be removed from the TV's front axle and 1500# added to the rear axle,
and if you wish to restore 500# to the front axle,
and if TV's wheelbase is 130" and rear axle to TT axles is 260",
Then:
the WDH would be adjusted to transfer 250# to the TT axles
causing 250*260/130 = 500# to be added back to the front axle, and
causing 250*(130+260)/130 = 750# to be taken from the rear axle.
The net load changes would be
250# added to TT axles, 500-500 = 0# change on the front axle, and 1500-750 = 750# added to the rear axle.
The theoretical net distribution would be
0 change on front axle, 75% added to rear axle, 25% added to TT axles
Versus your measured values of
4% removed from front, 82% added to rear, 22% added to TT axles.
Ron
