BenK wrote:

Using Bens diagram above, I agree the frame of the trailer is pushing towards the tow vehicle when the chain is tightened. No question.
I believe the bottom arrow is wrong. When the chain is tightened, it does not know it is tightened from one side. It is in tension and therefore pulling both sides, so the arrow should go both ways to demonstrate forces in both directions. The hitch ball is the hinge. You tighten the chain until the rectangle is formed. Once the rectangle is formed, the truck and trailer are leveled. This action also causes the hitch ball to rotate toward the truck which would set the pressure from the hitch pawl lower on the ball. I suppose some weight might be transferred forward but not knowing the math involved, I don't know how much is. I don't see any lever because the chain is not rigid, even its mount to the plate is not rigid. Technically, that is a hinge too. To me it looks like you tighten the chain and this action lifts the trailer tongue and hitch ball. I see that by over tightening the chain, the back of the truck would be lifted higher and that action would distribute weight forward, so I guess to some degree it does distribute weight, just not traditionally by prying.
Anyway, I'm not sure. Just throwing it out there.