Welcome to brain Stuff from how stuff works dot com where smart Happens. Hi'm Marshall Brain with today's question, how does a self winding watch work? You may be able to remember when the first electronic courts watches came out, they were going to be the end of normal mechanical watches, just like videotape was going to be the end of movie theaters. Somehow, it hasn't worked out that way, and self winding watches are more popular than ever. So how
does the self winding watch work? The easiest way to see it is to go to a store that sells watches and look at a skeleton watch with a clear back. You will see a semicircular metal piece that's the heart of any self winding watch. Relatively speaking, this semi circular piece is fairly heavy, and it's therefore affected by gravity. As you move the watch, this piece will move so it's always pointed towards the ground. As you walk with your arms swinging back and forth, this piece moves back
and forth. Inside the watch, the piece is attached to a gear train that gears it way down. Each movement of your arm winds the spring. The tiniest bit but Since you move your arms so much, it keeps the watch wound easily. The spring and the watch stores enough energy to keep the watch going for about a day and a half if you leave it on the dresser. Do you have any ideas or suggestions for this podcast? If so, please send me an email at podcast at
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