[Justin Stiltner]

You could use the chain in the traditional sense, with 2 sprockets and the chain running around those like you would with a motor powered sprocket then attach the rod of the cylinder to the chain in the middle span between the sprockets. This way the cylinder powers the chain in both directions without using springs, ect. If you want a good example of what I mean go look at the curtains on your stage.... 2 pulleys, and your hand grabs one of the ropes, you can either pull down on it or push up on it (which actually pulls the rope up) this way your arm is powered in all directions of movement, which I have learned is a very good thing, gravity is nice, but with cables and such which can tangle when they become slack I prefer to power them in both directions.