"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

Air powered linear actuator ? You can control it with electric air valve.
They go both directions. Problem is with vibration in some precision
applications. Some have a brake. Much faster than most other actuaries. I
helped make one used on a medical imager.

http://www.ebay.com/sch/Air-Actuator...inear+actuator

Greg