This valve would be constructed using a Cross fitting any size would work and instead of the pilot valve releasing pressure it would apply pressure and move the piston against the spring and when the pilot valve is released the piston would move back into place.
I have an example picture of it below this is just an idea and someone else can prolly draw it better or assemble it better.
Cross Valve
This won't work. When you design a valve, you have to keep in mind that this isn't a 2-dimensional object. The O-Rings will only stop air from going past them and if you put O-Rings onto the entire thing there would be too much friction. This has been thought up before here...
http://forums.spudtech.com/topic.asp?TOPIC_ID=12065
This gives me some inspiration towards a combo of this and one of my old ideas though.
http://forums.spudtech.com/topic.asp?TOPIC_ID=12065
This gives me some inspiration towards a combo of this and one of my old ideas though.