Flywheel made with LEGO 9686 Machine&Mechnism.
It is a tool for testing inertial forces, I know it was created by Leonardo da Vinci.
When the device is rotated, both wheels receive the centrifugal force and the device is unfolded. Even if the power is cut off, the inertia remains due to the weight of the wheel, so that it stops rotating.
You can turn off the power of the gear connection part manually and rotate the flywheel manually.

свернуть