My team has had some experience with these. Pretty much, its a way of taking the linear motion of a piston and turning into rotary motion. It works by a piston moving a rack, which turns a pinion, much like a car steering wheel works (kinda). This allows you to pneumatically turn something. The rotation is normally limited, so it does not behave like a motor. But if you only need to rotate something out of the way, like a door or something, it would turn it.
As for force and power, the one we used was a half inch bore cylinder, so ours had very little force. it was able to lift the small moment arm we needed it to, but it wouldn't be able to fight much resistance. Also, it behaves just like a cylinder, so if you're looking for speed (or kick!) you would need a larger bore than what we used, because ours simply lacked power of any sort. You can also play around with the air speed regulators to find the optimum power.
This is a different model than the one we used, but its the same general thing:
http://www.bimba.com/Products/PneuTu...taryActuators/
you could also look for others actuators. In my humble opinion, if you want to use it as a kicker, I don't think this will be what you're looking for. However, you're free to experiment, and if you find it works, let me know!
Also, one more thing from my team's experience... be careful with them, they can break
