Inspired (accepting the challenge) from this thread: One Motor Drive?
We present the first VEX legal zero motor drive robot: the “Pneubot”
Videos and pictures here: https://drive.google.com/folderview?id=10uKiGBla9q0GsQIuBDOkEvovOYLC8nLp
Technical details: the crankshaft is powered by a pair of double acting cylinders offset by 90°. A V5 rotation sensor provides feedback to the brain to actuate the solenoids. The timing is mechanical, just like on a car engine.
This little robot has become our new example pneumatic trainer, since it contains almost every pneumatic component, along with code on the brain (PROS).