open/closed valve spool

If you figure that spool out you will be waaaaaaaay ahead of Vickers, Rexroth, Parker, Denison, DoubleA and any other manufacturer of 3 or 4-Way Directional Control valves I am familiarr with.

One possibility to achieve what you want would be a Pilot to Close Poppet design like Nachi has, or maybe had, have not looked that one up for awile. It uses 4 poppets and a D03 4-Way Directonal Control to pilot the Poppets.

Using a D03 Directional Control with "P" Blocked, "A" and "B" to "T" Center condition gives an All Ports Open center while the same D03 valve with the spool reversed would give All Ports Blocked center.

The Nachi valve only comes in a D08 or D10 size.


Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.
fluidpower1 @ hotmail.com

You need to provide more information about the valves usage, port location requirements, flow and pressure before any suggestions can be made.
Depending on these features and the cost target, will determine options.

various sectional or stacked spool valve mfrs provide a tapped port in the outlet section to convert from open center, closed center, power beyond, etc. functions. These typically have some sort of center pilot signal that unloads the first section.

If this is what you are describing, it should be fairly simple. If you mean both options on the same individual spool machined part, I'm with bud-that is a challenge way beyond my knowledge.

k