Load sensing proportioning valve

I have a 2000 Ford Ranger 4x4 off road package.

What does the load sensing proportioning valve (LSPV)help control? Brakes cordinantion between front and rear? Does it send signals to the drive shaft?

My guess - the heavier the load in the bed, the more pressure to the rear brakes. Unloaded pickups can be a handful without it.

This is a variable brake proportioning valve in-line with the rear brake line. It has a rod that follows the riding height of the rear axle. If the rear of the truck sits low because of a heavy load in the back, the valve shifts more braking power to the rear. If the rear end sits high with nothing in the back, the valve restricts brake power to the rear to prevent wheel lock-up. This has been used in trucks for years, and I had one in my 1990 Toyota pick-up. This should be a simple mechanical device. No electronic sensors needed.