Reply to "Proportioning valve"

Ron,

Thanks for the information. I think you are on the right track but the Pantera valve only has one spring.

We think (The Donut Derelicts team) the valve metering action takes place between the lower edge of the piston flange and the upper edge of the black rubber seal that you see in the picture. With the piston in the home position (up), the upper ring you see in the picture keeps the black seal spaced down a small amount so fluid can flow through the opening. The tricky part is what takes place under high pressure and how is the pressure differential created to move the piston down. Somehow the piston must move down and restrict pressure flow by closing the gap between the seal on the bottom surface of the piston. The piston is free to move down (under opposite spring pressure) because the piston shaft can move down and out the bottom of the housing. Once the seal closes pressure would be limited on the outlets. Some of the crew thought the size of the piston and the pressure drop was related to the size of the master cylinder piston and the size ratio created between them.

Mike