All mechanical watches work in a similar manner. They require a movement of a series of gears to “tick” of increments of time, which in turn registers as movements of the hands on the face of the watch. A rotor in the watch sits on a staff in the middle of the watch’s movement. It rotates in a circular motion and winds the mainspring which is the source of power in mechanical watches. With an automatic watch the winding of this spiral spring is done automatically with any arm or wrist movement.
Self-winding, automatic watches work great for people who wear the watch each day, but if you do not wear the watch frequently, it needs manual winding about twice a week. Even automatic watches will stay working better if they are wound manually about once every two weeks because this helps keep the watch lubricated. It is a misconception that automatic watches never need any winding, since it all depends on the movement of the arm to keep it functioning well.
A power reserve