Weight distributing hitch math?

Ron Gratz wrote:

Francesca Knowles wrote:
Is the "force" required to shift the weight measurable, and if so how much is required in the above example?

Francesca, are you referring to the upward force which is applied to the rear ends of the weight distribution bars?

Ron

I think so- I'm not exactly sure WHAT force I'm referring to. My very dim understanding of the way levers work is that there has to be some force exerted somewhere in order to shift the weight.

Thing is, I keep looking at pictures, and it appears to me that the bars/chains must be pulling on the trailer tongue at the connection point, pushing it down against the fulcrum provided by the ball. I s'pose that's wrong, but it's the only logic my simple mind can come up with that explains why the front end of the tug gets "lighter".