[nickcrowhurst]

Originally Posted by 3DogNight

Please correct me if I am wrong but as I understand from your equations, D is in direct relationship to L. Jerry

Jerry, I'm glad you enjoyed the analysis. I'm the dreaded in-law at my kids' place for Thanksgiving, so I'm hiding out of the way on the PC. Unfortunately, D is not in a direct relationship to L. Equation 8 shows that it is much more complex than that:
D= (T*H*L)/(B(H+L))
You can see that B, H and T are also involved, and L is on the top as well as on the bottom of the equation.
59toaster gives excellent advice in his thread. As he says, the important thing is to get the front axle back to where it was before hitching up. If you put the accurate figures into the equations, you will establish the minimum chain tension required for this. You then require the minimum strength bars that will provide this tension, so that the connection remains flexible. As 59toaster said, this is particularly important with the Equalizer, where sway control depends on loaded springs. One point to bear in mind is that manufacturers may define the capacity of their hitches in different ways. If they are defined in terms solely of hitch weight, then this is oversimplifying, as can be seen from the analysis. In practical terms, though, it is probably an acceptable compromise. The only accurate way, as Markdoane says earlier in this thread, is to obtain the spring deflection/chain tension figures from the manufacturer. It would be interesting for you to input your accurate figures, when known, and to come back to us after that. The figures obtained can be combined with the practical experience of forum members like 59toaster, and a body of knowledge can be established. I hope this helps, even if it doesn't simplify this complex issue.
Nick.