A quick question about VEX Pneumatics kit with single-acting cylinders.

I am thinking about ordering the VEX Pneumatics kit with single-acting cylinders (I found it available from another online store) and I had a quick question to ask of someone (or team) who has one.

I know that the single-acting pneumatic cylinders are powered pushing out and have a spring return to pull them back in. I was just wondering how strong that spring return is?

For example: If I were to use the single-acting cylinders to lower the back of a storage bin on a Clean Sweep robot to dump it, would the springs be strong enough to keep the back up with the weight of the balls pushing against it?

If anyone could help me out, I would really appreciate it.


Based on my experience, I would say “yes,” but you know this will depend on the specifics of your design. Your mileage may vary, use at your own risk.

Thanks for the quick reply! (Yes, I know it’s crazy being up so late posting on the forum.)

I kind of figured it would be one of those type of answers. I am beginning to think that the kit with the double-acting cylinders might be the better one to get even though it is a little more expensive. At least that way there would air pressure keeping the cylinders retracted.

Any thoughts?

In general, the spring in the single-action cylinders is not going to be strong. If it were strong, then the cylinder would have to fight against it to extend the plunger. Fighting against a strong spring would rob the entire unit of much of its ability to do something useful for you.


Well when you get them you could measure how strong they are with a postal scale. Attach a piece of string to the end of the cylinder extend it and then connect it to a postal scale.

When the cylinder retracts it will pull the scale down and give you a fairly accurate measurement of how many pounds of pulling force it has (if it even has pounds - ounces?)

As was said the spring will not be super powerful because the air pressure must also compress the spring so the more powerful the spring the less powerful the air push is.

That’s what I was thinking too. That’s why I wanted to check with someone who actually had the single-acting cylinders before I ordered them - just to be sure. I’m thinking that it would probably be better to order the double-acting cylinders instead.