Rules around pneumatics

Is there a limit to how many pneumatic cylinders (not reservoirs) are allowed on a robot?

Do you mean pistons? If so, there is no limit to the number of pistons on a robot.

If we want to use proper terminology (which I prefer, since we’re trying to educate a new generation of engineers and technicians), then they are indeed called “cylinders” as in BARobotics original post. The cylinders are either single or double acting. The reservoir, or air tank, might be a little confusing in appearance since it is custom made from an air cylinder by putting an end cap on both ends.

The limitation on pneumatics is having only 2 reservoirs. The more cylinders a robot uses, the faster the air pressure will drop. Double acting cylinders use more air than single acting, since they return by air. Single acting cylinders have a spring return, so they don’t require so much air.

A double acting cylinder may be used like a single acting cylinder by not connecting one of the air fittings, plugging the air hose at the solenoid valve, and using rubber bands to retract the cylinder.