Compressed-Gas Powered, Pulsing Rotary Motion

[HeXeN]

Hello fellow scientifiteers.....heh

Well, i have this idea for a new kind of paintball gun, and i need a way to use compressed air to power a rotary in pulses, like a clock.

My first idea was to use a piston which would work a ratchet, however my entire goal here is to eliminate linear motion. Another crazy idea i had was to have the gas power a turbine and use extreme down-gearing to slow it waaayyyy down....but the problem is that i need this thing to move in very short, very precise pulses, and i need it to do it very very quickly, as in a matter of milliseconds....

So my third idea is to use the air to power a piston that can also move up and down and is on a crank shaft, and i would do it so that one stroke of the piston moves the rotary the correct distance...this would seem sort of linear, but it doesent work as if it were linear.

If worst comes to worst, i can use an electric motor, but it would be much better if i could get the whole device to work on one power source, being compressed gas (which, in the case of paintball, is always either CO2, pure Nitrogen, or just plain air).

Frankly, I can't think of another way to do this...if anybody has any ideas, feel free to let me know about em....=)

[Cap'n Refsmmat]

Hows about an air turbine with a spring valve. When the pressure builds up, it lets air through and spins the turbine. Then, since the pressure is released, it closes, and so on.

[HeXeN]

Yeah, but wouldnt it take a while for the turbine to accel to full speed?

[Cap'n Refsmmat]

No, it would just turn it a little bit in rapid pulses, making it jerky.