Any stop damping shaft, also called "free stop", the concept is a bit abstract, let me give you an example first, so that you can have a clearer understanding of "any stop shaft"! I believe everyone is familiar with notebook computers. The part where the notebook screen and the host are connected requires a hinge!
A careful friend will find that when we open the laptop screen, does it require a certain amount of strength, and this strength does not need to be great, just right! And when we stop turning, the screen will not shake up and down, staying where we want!