I've amended my older E-mag animation to actually show the pressure changes caused by the RT valve. Check it out: (fast; slow)

Basicaly what happens is the downward force on the chamber shutoff increases when the RT reg opens up (letting the HP air though). The increased pressure places more force on the pin, so the trigger is assisted back to the open position. When the chamber shutoff is finally opened (pin goes down) the RT reg is pushed closed, maintaining a lower pressure after it in the system. The pressure on the chamber shutoff is then decreased and it starts over.
Very nice!!
Basicaly what happens is the downward force on the chamber shutoff increases when the RT reg opens up (letting the HP air though). The increased pressure places more force on the pin, so the trigger is assisted back to the open position. When the chamber shutoff is finally opened (pin goes down) the RT reg is pushed closed, maintaining a lower pressure after it in the system. The pressure on the chamber shutoff is then decreased and it starts over.
Very nice!!

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