Hehehhe.. see what I start? hahaha.
reb1, what you talk about sound like what I know of as a 'surge brake', it is what big heavy things we would tow with a truck like a fork lift.
When the drive vehicle slowed, the weight of the load of what what you were pulling would activate it's hydraulic brakes when it push against it.
It was located right on the hitch.
I remember one time, again many years ago in my teens driving one of my dads roofing trucks.
I was coming down a little hill in a cab-over long flat bet truck that was empty, but pulling a big 2 story forklift with a surge brake and when I started to come up to the red light I braked as usual but didn't slow down and started jackknifing.
The long truck had no weight on it, and the surge brake on the fork lift had failed.
All I could do was hold down on the horn and jackknifed into the intersection.
Pretty darn scary especially for a 16 year old kid but no damage to anything.
Once I got out of intersection I cheeked the the surge brake fluid level and was empty.
Some brake fluid and I was I on may again but never forgot to check that again.
I do love the trailer idea's though, but please rOOt4d, do show us some pics of the business end of the connector as it just looks too fun to me ;-}