# Rodless Cylinder

Instead of taking the FIRST Forum thread off topic i’ll just post what i’m pretty sure they are talking about…

sanddrag
What is a rodless pneumatic cylinder?

Nate’s Forum Notes

Rodless Cylinder from Festo

The only reason i’m kinda sure this is what they are talking about is because Andy Baker had one of these that he was supposed to show someone at Nationals…

PS. I may be wrong

Thanks but I still don’t really get it.

From what I can tell, it acts basically like a Chinese Finger Trap. Positive pressure forces the cylinder to extend, and negative pressure forces the cylinder to contract.

But…
It’s 4am, I may not understand what the hell I’m talking about, and it might operate in an entirely different way…

/me should go to sleep…

If you want a coherent reply, as opposed to this one, please tell me… I might be able to decipher what I meant tomorrow/later today, sometime…

i think it may be the other way around, where positive pressure contracts it, and negative expands. it’s like a chinese finger trap in that when you push in, it contracts in length, and expands in diameter, and you get out, but when you pull, it just gets longer and smaller in diameter. now, this may completely wrong (heck, i’m a programmer :p), but i think it’s right.

We also use what can be know as a ‘rodless cylinder’ in the plant for very long stroke applications. (about 10ft)

Think of a long fixed length cylinder. Cut a groove along the entire length that completely through the cylinder material. Now place a shuttle inside the cylinder that has the same diameter as the inside bore of the cylinder… Lastly you put some sort of a seal over the groove that unseals at the location of the shuttle then seals on both sides of the shuttle as the shuttle moves back and forth. Applying air pressure to either side moves the shuttle the length of the cylinder yet there is no piston inside just the shuttle.

Ohh well this is another version of a ‘rodless cylinder’

Matt

*Originally posted by Ian W. *
**i think it may be the other way around, where positive pressure contracts it, and negative expands. it’s like a chinese finger trap in that when you push in, it contracts in length, and expands in diameter, and you get out, but when you pull, it just gets longer and smaller in diameter. now, this may completely wrong (heck, i’m a programmer :p), but i think it’s right. **

I love browsing CD at 4am…

I read something in a book that was like this only it wasn’t called a roddless cylinder it was called “air muscle” basicaly a tube than can expand and contract like a arm or leg muscle.

*Originally posted by The wheelman *
**I read something in a book that was like this only it wasn’t called a roddless cylinder it was called “air muscle” basicaly a tube than can expand and contract like a arm or leg muscle. **

If you download the program that is linked to on the page that Clark posted, you can see a few small animations of how the cylinder is supposed to work, and <edit>oh boy!</edit> does it look sweet…

/me awaits next year’s kit with much anticipation…

<edit>
http://www.festo.com/INetDomino/coorp_sites/-snm-0135166248-1028116432-0000014401-0000000008-1028285022-enm-en/9629a4820d7e6468c1256b410050e38e.htm
</edit>

What about what they gave us in 2000 it was a pneumatic cylinder that had a magnet or somthing in in it that would slide around the cylinder. Mmm bad explination if you look in Ed Spark’s Cad library under archive you will find it there. This more than likely is what they are talking about. http://www.firstcadlibrary.com/pages/archive.asp Scroll down it looks like this :http://www.firstcadlibrary.com/images/rodlesscylinder.gif

soooooooooo nice. I just got another plan… hehehe.

sanddrag
What is a rodless pneumatic cylinder?

They’re also called “Air Muscles”…

Mechanically, imagine a cylindrical balloon in a fishnet mesh wrapper, like a bag of oranges, or the chinese finger trap. When you inflate the balloon with pressure, the center of it expands. However, the mesh wrapper attempts to keep the balloon the same volume. The shape changes from cylindrical toward spherical, with constant surface area. Therefore, as the center inflates, the ends of the mesh wrapper must pull toward each other.

If one side of the mesh is attached to the inflation nozzle end, and the other end to a metal collar, ring, or other attachment endpiece, they’ll pull toward each other as the muscle inflates.

Now that you see that, dip the mesh wrapper in rubber. The mesh/rubber combo now is more like the reinforcing belts within a vehicle tire. However, it still works the same way. The rubber simply creates a protective coating over the flexing mesh. I believe this is the kind of Air Muscle Festo provides, but I’d have to check to be sure.

If you wish to make an Air Muscle for yourself, check out this page:
http://www.imagesco.com/articles/airmuscle/AirMuscleDescription01.html

I think it would be VERY cool if the Allowed Extra Materials list would allow the creation of Air Muscles!

• Keith