Elliptical gears

Oval or elliptical gears are a type of gear that have an elliptical or oval shape. In contrast to traditional gears with a circular shape, these shapes are more non-standard and can be used in specialized applications, such as transmissions with unusual dimensions or where traditional gears are not suitable. Such gears can be designed individually for specific applications to meet particular mechanical requirements.

My interpretation of the model found on the web (link in the description).