Electrical Aerial Mechanism - How does it work?

How does the extending mechanism work? Really need to find out since the mechanism would be really be useful in a project im working on at the moment.

I know it has a motor but what controls/drives the aerials extension and makes it stay up?

Inside the power antenna assembly, there is a gear that rotates by the antenna motor. The gear will push or pull the mast extension cable just like a fishing reel. The only difference is this mast extension cable is made from nylon and has teeth (see pic). Then the extension cable will push the mast up (or pull down).


Click on thumbnail for larger pic.

See more here
http://www.sof.ws/probeaudio/antenna.html