On 2013-04-07, Steve B wrote:
I need an actuator, but one that is air powered preferably. Instead of the
shaft coming out slowly, I want it to shoot out instantly upon air pressure
hitting it. What are those called?

I think you might be thinking of an "intertia" nutcracker. I've never
used one, but I understand they work pretty well on pecans.

http://tinyurl.com/66zwabj

Since they are powered by a rubber band, should be pretty easy/cheap
to make yer own.

nb