# Cylinder Question



## RLukard (Sep 18, 2010)

I have been looking at cylinders for my grave jumper. I have been debating wether to get a double action or single action. I really don't want the single action, so I'm leaning toward the double action. If the weight of the skull mounted on the cylinder rod pushes the rod down, do I need a second air supply to also push the rod down?


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## The_Caretaker (Mar 6, 2007)

With a double acting you will need another valve and air line to push the rod down, so you need a valve to extend and one to retract, the valves i believe need to be 3 ways so they allow the air to bleed from the cylinder.


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## niblique71 (Dec 2, 2009)

Double acting cylinders have power in both directions. When your valve is at rest it directs air pressure into one end of the cylinder (presumably forcing your prop to be at rest). When the valve is activated it redirects the air to the other end of the cylinder causing it to move. When the valve is once again turned off, it will return to it's first position. Even if your prop doesn't reset with gravity, the air pressure will do it for you.


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## gadget-evilusions (Jan 26, 2007)

3 way valve for single acting. 4 way valve for double acting. Using a single acting cylinder and 3 way is always more expensive than a double acting cylinder and a 4 way valve, plus you get better control over the speed in both directions with a double acting cylinder.


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## bourno (Jan 21, 2006)

I always buy double action air cylinders. You don't have to plumb them for double action if not needed and can use them as single action usage.


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## kprimm (Mar 14, 2009)

Absolutely for the small amount of extra money the double acting is much better. There is so much more you can do with them. For a simple pop up though I think A single would be fine. Really depends on what you want the movement to be.


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## Shier Terror (Jul 17, 2009)

For my pop-up props, I use a simple door closer. I feed an air line into the back to push the piston up and it falls back on its own. It really depends on what you want the prop to do. I try to use door closers because they are $10. I use other cylinders when I want the prop to do something special. I have a double-action cylinder for one of my props that pops out and then snaps back quickly.


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## bert1913 (Oct 27, 2011)

double action with speed controls


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