Community Pneumatics Information

So as many people have said, it has been a while since pneumatics were used, and many people have not used them at all. So I created this thread as a way where those who have used them can share their knowledge of them, as well as other resources.

7 Likes

This tutorial is very easy to understand and is a good intro to vex pneumatics.

More over what each component does.

https://wiki.purduesigbots.com/hardware/pneumatics

Pneumatics are very simple if you know how each component functions.

5 Likes

Here’s some more information:

4 Likes

I feel like the community should learn about the vocabulary of pneumatics:
680px-Pneumatics_Kit_2_Annotated
Both single acting and double acting cylinders have two modes.

Single acting:
Mode 0 - Off
Mode 1 - Push outwards

Double Acting:
Mode 0 - Push inwards
Mode 1 - Push outwards

This will mean that double acting will use a whole lotta more air than single acting, so choose your cylinders wisely!

Pressure regulators allow you to restrict how much pressure can go to the cylinders. If you only need a small amount of force for something to move, you can attach a regulator before the solenoid (which is a motorized switch that enables and disables airflow electronically) so you won’t use as much air.

Pneumatics can leak and sometimes its hard to tell where things are leaking. That being said, it is a good idea to have most components accessible and easy to maintain. That way, you can dry test your system and stick your ear up to a plug to detect air leakages (on second thought maybe not a good idea because if a plug goes poof you may bust an eardrum). Another alternative is using water or grease on the lip of a plug to detect bubbling.

PUMPING RESERVOIRS SHOULD NEVER EXCEED 100 PSI. It is really dangerous to exceed that. I would highly advise using a motorized handheld battery powered pump as using a freaking bike pump is gonna either exhaust you or you may slip while pumping and hurt yourself.

Reservoirs are quite interesting to connect to the robot. In VEXU, you can connect a reservoir with 3D printed parts:
image
If you are not in VEXU you can do something similar like cutting a hole in a 5-wide C-Channel to make a similar bracket. Another alternative is just zip-tying the reservoir onto your robot.

8 Likes
1 Like

To elaborate a bit more on the difference, double-acting cylinders use air to both extend and retract, while single-acting cylinders use air only to extend, and have an internal spring to retract. If you are purchasing new pneumatics, I would recommend buying only double-acting cylinders. You can use them just like single-acting by connecting only one end of the cylinder (leave the other end open to the atmosphere) and plugging the extra port on the solenoid valve. Then, either use a rubber band or gravity, depending on the mechanism, to retract the air cylinder.

8 Likes

Dies anyone know how fast and how powerful a single acting cylinders retraction is?

This is usually weaker than the extension force. I don’t believe there is a hard and fast rule, it really just depends on what spring the manufacturer uses in the cylinder.

2 Likes

Pretty fast (it’s spring loaded) but not powerful enough to do anything useful. You can increase the retraction speed and force by adding rubber bands, but now you’ll need more air to extend the cylinder. This is the advantage of double acting cylinders: you can set the retraction force as needed, from nothing (leave the exhaust port open), to full power on the cylinder in both directions.

3 Likes

How do you know which one is which without testing them

If the cylinder has a port on each end, it is double acting. If it only has a port on the end away from the piston, it is single-acting.

2 Likes

Like an electrical port?
E:Nvm I looked on the vex website and understand now. The picture Connor posted with the labels messed me up cause I read to fast.

To be more clear, air cylinders have a front or nose, which is where the rod comes out, and a rear or tail, which is opposite where the rod comes out. The piston itself is inside the cylinder and moves back and forth. Single acting cylinders have a port only at the rear. (The port is the threaded hole into which you screw the fitting)

5 Likes

Fair point. I should have said operating rod, not piston.

2 Likes

Found this.

1 Like

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.