@Dkayak
Thanks for posting these real-world figures as an example how weight distribution hitches effect load.
From the raw data, and I could be missing something glaringly obvious but it seems that in the 1st scenario where the springs were tensioned by the installer, there was a net transfer of 80 lbs from rear to front axle of the tow vehicle with the WDH connected. Interestingly, the weight on the trailer axle did not change, remaining 5360 with hitch connected or disconnected.
In the 2nd scenario, with the springs tightened up to properly level the vehicle, the tow vehicle front axle gained 300 lbs and the rear axle lost 400 lbs (100 lb difference between 300 and 400) . Interestingly, the weight of the trailer axle did
not change at 5240 lbs with hitch connected or disconnected.
So somehow there is 100 lbs to be accounted for. If you look at measurement error of the scales when comparing the same mass there is up to 40 lb error in tongue weight, 60 lb error on any individual axle, 80 lb error in measuring the same tow vehicle, and for the gross combined mass a 200 lb error (10 860 versus 10 660).
So if I was to guess, I would say in the 2nd scenario there was a weight transfer of 300 lb and the unaccounted for 100 was measurement error in the scales themselves.
It does make it hard to interpret when there is this amount of precision error in the test device.
What mostly surprised me is that in neither scenario did the weight over the trailer axles change. Trailer axle weight remained 5360 in the 1st scenario with hitch connected or disconnected, and in the 2nd scenario 5240 with hitch connected or disconnected. I’m not sure where you’re getting the 140 lb weight transfer to the trailer in the 2nd scenario?
That’s okay, I probably missed something. One of the reasons I did not do a dual degree which included physics is because a) I’m not totally crazy and b) the math started giving me headaches and there were much more interesting ‘figures’ walking around campus
!
All that said, it looks like the WDH is doing its job both quantitatively (even given the precision error between measurements) and qualitatively with subjective feel. I was a little sceptical at first when I saw an Internet video from the hitch maker who essentially did the same test as yourself but the figures were to my understanding grossly spurious. I won’t reference the video here but there were significant discrepancies between repeated gross combined weight (when I calculated the weight over all axles) which I understand is impossible unless for example you weigh the rig on different planets
.
So congrats, I think you have gone above and beyond what most people would do and the rest of us can benefit from your experiment. The experiment
does agree with the theory and as my friend Feynman says, “if it disagrees with experiment, it is wrong.”
Cheers and thanks again
David