How does an automatic watch hold a power reserve?

Question

And how does mere movement power it? Cheers

In: 3

Answer 1

“Automatic” watches are mechanical watches which are self-winding. Mechanical watches store their power in the form of metal springs, wound up to slowly release their energy through the mechanism of the watch.

Instead of being wound by the turning of a small stem by the user’s fingers, an automatic watch uses a weight within the watch to crank a sort of ratchet mechanism. As the orientation of the watch changes the weight will swing down and provide force to crank the watch’s spring tighter. Since people move around quite a bit a small amount of that force is harvested to keep the watch wound.