Depressurizing a Piston

My team is currently experimenting with pneumatic cylinders, and we were wondering if there is any way to remove air pressure from a piston during the match so it no longer outputs force. The solenoids we use are the Double Solenoid Valve, Mead, 1/8 NPT. Will these work, or do we need to look into an alternative solution?

So the answer is… complicated.

It depends a LOT on the answer to “Are you OK with not powering the cylinder at all in one direction?” If the answer is “Yes”, then it’s highly doable but you’ll want a single solenoid (or a plug will probably work instead). If the answer is “No”, then it’s going to get MUCH more difficult to do legally due to R87 (though R77G might possibly have a clue).

Out of curiosity… Are you deploying a climb hook with a cylinder, then wanting to pull with a winch instead?

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A single solenoid! Fantastic! We’re currently messing around with several ideas and a couple prototypes. One was to have a light pneumatic mechanism to lift up a climbing hook and then winch (similar to Sherbrooke’s Ri3D, but hopefully with less moving parts).

So the way you’d rig is to plumb one side of the single solenoid to the extend side of the cylinder (and as a matter of precaution, you want that to be the normally CLOSED side). The other end of the cylinder is left to atmosphere; the solenoid’s other side gets plugged (depending on the model, you may not have another side). Fire the solenoid to raise, vent to depressurize.

You can do the same with a double solenoid, just means you have to be intentional about “Go to plug side”.

Also, you may want to look at a spring-return cylinder (give the climber a little assist).

One way. Use a 3 position double solenoid with open center. Like this. With both solenoids denergized, the cylinder is completely depressurized. Holding a solenoid on will direct the cylinder one way or another. When robot is disabled, the valve will be in the center position which will completely depressurize the cylinder. Rule legal because one valve will completely depressurize the system

For our Stronghold robot we had a shooter/intake arm that was on a large pneumatic piston. We set it up with three settings. Up, down, and “float”. We used an extra solenoid and plumbed such that activating it would vent the air inside the cylinder to atmosphere. Float mode was used when the arm was down and had a boulder inside and we needed to cross a defense. Didn’t want the boulder or the arm itself to catch on anything on the ground. This way the whole assembly was free to bob around and contour over whatever we were driving over.

I’ve done this using two 3-port valves using a separate one for extend than retract.

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