Posted: Fri Nov 09, 2007 5:35 am
There's a lot of flow rates to balance in this equation, getting it right could take some trial and error.
I used a similar system in my cartridge fed pneumatic prototype:

Even though the filling hole was tiny, air still leaked through the barrel as the piston didn't reseal properly. I had to restrict the filling supply to tiny levels for the pilot volume to pressurise. A less tight fitting piston and larger chamber would probably have solved the problem, but being epoxy construction, not that easy to fiddle with the internals once you've built it.
I used a similar system in my cartridge fed pneumatic prototype:

Even though the filling hole was tiny, air still leaked through the barrel as the piston didn't reseal properly. I had to restrict the filling supply to tiny levels for the pilot volume to pressurise. A less tight fitting piston and larger chamber would probably have solved the problem, but being epoxy construction, not that easy to fiddle with the internals once you've built it.