<font color="green">Originally posted by Clide, but stupid Snitz archived it</font>
Well I made this flash animation in hopes to explain piston valves for the most part. Let me know if this helps anyone figure them out. Those who already know, please point out if you spot something wrong.
<font size =+2><b>Phase Explainations<br></font><font size =+1>Applies to all Models</b></font>
You may need to watch it several times because there are many things going on at once. This assumes you know the relationship between pressure, surface area, and force (pressure * surface area = force)
<b>Phase 0:</b> Basically just the gun in its pre-use state. No pressure in the gun.
<b>Phase 1:</b> An air source is connected behind the piston. Air enters the pilot chamber and the pressure pushes the piston against the rear of the barrel or chamber port.
<b>Phase 2:</b> Air continues to flow through the input and leaks around the outside of the piston or through an equalization hole into the main chamber. Once desired pressure is reached, the input flow is cut off and the gun is ready to fire.
<b>Phase 3:</b> The exhaust valve is opened and the pressure begins to fall in the pilot chamber. The exhaust must exhaust faster than the equilization hole can leak air back into the pilot. Once the force pressing on the back of the piston falls below the force acting on the front of the piston, it begins to slide back. Suddenly there is more surface area exposed on the front of the piston, and the jump in force slams the piston back leaving an opening for air to flow into the barrel to accelerate the projectile.
The exhaust valve is closed and a new projectile loaded. The gun is then back to it's original condition, ready for the cycle to repeat.
The main thing to notice between the different types are the forces caused by pressure. Of course forces could be changed by changing the changing the piston/sealing port diameter, but in the general senario like the one shown, with a constant barrel diameter between all types and a tee slightly larger than the port, the barrel sealing valve will have the same forces as coaxial in the closed position. Barrel sealing will have the highest opening force, coaxial will be in the middle, and chamber sealing will have both a low closing force and a low opening force.
<font size=+2><b>Coaxial Piston Valve</b></font>
<embed src="http://gbcannon.com/flash/coax.swf" quality="high" bgcolor="#ffffff" width="550" height="350" name="coax" align="middle" allow$criptAccess="sameDomain" type="application/x-shockwave-flash">
<font size=+2><b>Barrel Sealing Tee Valve</b></font>
<embed src="http://gbcannon.com/flash/barrelseal.swf" quality="high" bgcolor="#ffffff" width="550" height="350" name="barrelseal" align="middle" allow$criptAccess="sameDomain" type="application/x-shockwave-flash">
<font size=+2><b>Chamber Sealing Tee Valve</b></font>
<embed src="http://gbcannon.com/flash/chamberseal.swf" quality="high" bgcolor="#ffffff" width="550" height="350" name="chamberseal" align="middle" allow$criptAccess="sameDomain" type="application/x-shockwave-flash">
Update: Now includes a control panel with play, pause, skip, frame by frame, and slow motion (took forever to figure out).
Update 2: Added labels for both the controls(mouse over) and the gun parts. You may need to Ctrl+F5 to see the updated flash if you viewed this page before. Also added a barrel sealing tee flash and tuned down the forces on the Coaxial flash to be more accurate compaired to the Barrel Sealing Tee flash.
Update 3: Added Chamber Sealing Tee flash, corrected minor bug with the forces on Barrel Sealing Tee flash, and fixed incorrect force displayed in the closed positon of Coaxial flash.