On Sun, 7 Apr 2013 16:37:07 -0700, "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?

Steve


There are pneumatic cylinders that will do that.
Start here
http://www.mcmaster.com/#standard-air-cylinders/=m84511