This is a cycloidal drive, one of the most torque-dense gearboxes in existence. The one you see in the video is a simplified, very humble and small fully 3d printed cycloidal drive, but even in this ...

Check out the 3D-printed cycloidal gearbox installed on my Solar Rover #2! See how this compact and efficient gearbox improves performance and learn about the printing, assembly, and testing process.