actuator question

until 5 mins ago when i read the turbos 101 i thought i knew about turbos, obviously not. but one thing i never knew is what is an actuator. i've seen them but what do they do, whats their purpose ? can you guys please explain?

thanks,
chris

Its the cylidrical piece on a internally wastegated turbo that sits long-ways on the turbo. It has a hose running from a tap on the compressor housing to the cylinder. It then has a rod coming out of the end of it connected to the flapper on the turbine housing. When boost is present, at a preset boost level, the actuator opens the wastegate flapper allowing exhaust to bypass the turbine impeller. It just controls(or activates) the wastegate flapper.

http://www.diamondstarmotorsport.com/boostparts_files/Garret-Wastegate-Actuator.jpg

http://www.wabe.net/silum/images/apex_turbo15.jpg

so its like an "internal wastegate" ?

so its like an "internal wastegate" ?
along the same lines. yes