The article doesn't really say much about this, but it's an interesting topic. There were several ways these kind of systems were implemented, using mechanica

The article doesn't really say much about this, but it's an interesting topic. There were several ways these kind of systems were implemented, using mechanical linkages, hydraulics, or electrically using solenoids. Animation of a mechanical link system: https://www.youtube.com/watch?v=j1OxWxYAGlc https://www.youtube.com/watch?v=j1OxWxYAGlc Hydraulic: https://www.youtube.com/watch?v=8Oh1pLl1--Y https://www.youtube.com/watch?v=8Oh1pLl1--Y