An automatic mechanical watch, also known as a self-winding watch, relies on a combination of mechanical parts and the movement of the wearer's wrist to keep it running. The movement of your wrist powers an automatic mechanical watch, giving it energy to keep running. Its working principle is mainly the following aspects.

 1. Oscillating weight: The key component of an automatic watch is a small semicircular pendulum called an oscillating weight. The rotor is usually located on the back of the movement and can move in any direction. It is mounted on a pivot and can rotate freely.

 2. Gear train: When the watch is worn on the wrist, the wearer's movement causes the rotor to pivot or rotate. This movement generates kinetic energy.

3. Mainspring: The kinetic energy of the rotor is transmitted to the mainspring through a series of gears. The mainspring is a tightly wound coil of special spring steel that stores potential energy.

 4. Escapement: The potential energy of the mainspring is released in a controlled manner through the escapement, which includes an escape wheel and an escape fork. The escapement regulates the release of energy from the balance wheel.

 5. Balance wheel: The balance wheel is a small wheel that swings back and forth at a constant rate (usually several times per second). It acts as the timekeeping element of the watch, much like the pendulum in a clock.

 6. Hands and dial: The regulating energy from the balance wheel is transmitted to the hands of the watch through the gear train, causing them to move. The hands indicate the current time on the watch dial.

 7. Power storage: The mainspring provides power for the watch, and the balance wheel regulates the release of this energy. Automatic watches will typically run without wear for 24 to 48 hours, depending on the design and condition of the watch. If not worn for a long time, the watch will stop running and will need to be manually wound or placed on a watch winder to keep it running.

 The movement of the wearer's wrist winds the rotor, which in turn winds the mainspring. The energy stored in the mainspring powers the watch's timekeeping function through a series of mechanical components, including the escapement and balance wheel. Automatic watches are prized for their exquisite craftsmanship and their self-winding mechanisms, which eliminate the need for manual winding on a regular basis as long as the watch is worn regularly.