Understanding an automatic transmission

I have recently bought a new car with automatic transmission. First time in my life driving such a thing (in Brazil, as in Europe, most people prefer manual gears). As a std::nerd, I wouldn't be happy until I understood how this thing works.

As a weekend amusement I made some animations to effectively "see" an A/T model functioning. The result can be seen at this page. There are a couple nice YouTube videos, too.

The animation is based on HTML Canvas and Javascript. Not the cleanest code around, but enough to make an useful example. I have tested in Chrome, Safari and Firefox.

One day I hope re-make them in WebGL with actual gears, like the YouTube videos (which I did not author). This will take more time, probably all major browsers including IE will come with WebGL enabled by default when I finish this :P