Non Circular Gear Systems

Gears are fascinating mechanical components and they have different size, shape, function and forms. It is sometimes to difficult or time consuming to make animations of a gear or mechanical component composed of gears, yet I wanted to show demonstration of these kind mechanism without any user interface. The best place to do this was to use good YouTube videos for this purposes. I will add a collection of such mechanism whenever I find a good one. I will appreciate if you direct me to a good mechanism so that I can add them to my collections.

While gears usually have circular shape, there are gears with nob-circular shape used for special purposes. The video given above show assortment of non-circular gears with various configuration including planetary designs. I guess what can be done with the gears are limited with human ingenuity.