What is an automatic mechanical watch? What is the principle behind an automatic mechanical watch?

　　An automatic mechanical watch does not use a battery. Because an automatic mechanical watch relies on the swinging of the arm to automatically wind the mainspring, it must be worn for more than eight hours a day to ensure accurate timekeeping.

　　Structural composition

　　The internal movement components of an automatic mechanical watch consist of mechanical parts, functioning as a balance spring watch powered by a mainspring. A mechanical watch is composed of a movement and exterior parts. The movement includes the gear train, mainspring, winding and setting mechanism, escapement and regulating mechanism, and motion works. The movement parts are assembled together by bridges and screws. The exterior parts consist of the case, dial, hands, strap or bracelet, and other components.

　　Automatic watches come in various structural designs, but their working principles are largely similar. The automatic winding device is installed at the back of the movement and can be seen by opening the case back. Swiss automatic watch movements are generally relatively thick. An automatic watch with a standard reversing wheel structure typically consists of an oscillating weight (rotor), reversing wheels, automatic transmission wheel, and automatic pinion. The rotor is fixed to the central rotor shaft with a screw. Under external force, it rotates around the centre, driving the reversing wheel. The reversing wheel pinion then drives the automatic transmission wheel, which in turn drives the automatic pinion. The automatic pinion meshes with the ratchet wheel teeth, causing the ratchet wheel to turn tooth by tooth to wind the mainspring. Full automatic watches wind the mainspring regardless of which direction the rotor turns, differing from unidirectional reversing systems, bidirectional reversing systems, or pawl-based ratchet systems. Fully automatic watches are currently the most common. ETA2892 movements and Orient 46941 movements feature bidirectional automatic winding. The vast majority use an eccentric oscillating weight (rotor or automatic weight), shaped like a semi-circular disc and made of heavier metal with a thicker rim so that most of the mass is concentrated at the edge of the rotor. It rotates using gravity and the swinging of the user's arm, driving a set of gears to wind the mainspring.

　　Operating principle

　　A watch relies on the elasticity of the mainspring to provide energy for running. When fully wound, its torque is high. As the watch runs and the mainspring unwinds, its torque gradually decreases. From the time the mainspring is fully wound up to 24 hours, its torque output is stable, during which timekeeping is relatively accurate with small errors. Beyond 24 hours, however, the mainspring torque drops sharply, increasing timekeeping errors. To ensure more accurate timekeeping, the mainspring should therefore be fully wound at regular intervals every day.

　　Instructions for use

　　When winding a mechanical watch, it is best to wind it back and forth using your fingers. Winding back and forth allows your fingers to bring the ratchet wheel back slightly, which provides a rebound deceleration effect to prevent gear collision, and winding back and forth is also much more effortless. If you always wind forward, the closer the mainspring is to being fully wound, the greater its rebound force becomes, causing a rebound every time you wind it. Each rebound increases the impact between the winding gears, making the gear tips prone to breakage.

　　Based on the gear ratio calculation, turning the crown a little over 18 turns is sufficient to keep the watch running continuously for 36 hours. However, because everyone's winding strength varies and the frictional force of the waterproof rubber ring inside the crown differs, it is best to rotate the crown more than 20 turns when the mainspring is fully unwound. When the mainspring is fully wound, it can theoretically sustain running time for 40 hours (barring special models), but accurate timekeeping cannot be guaranteed after 24 hours.

　　When the balance spring is in a stationary state, applying a certain torque to the mainspring (i.e. winding it by one turn) without shaking the watch should cause the balance spring to oscillate automatically, which indicates that the sensitivity of the watch is high. If the watch only starts running after being shaken following winding, it indicates that the sensitivity of the watch is low. This phenomenon is generally caused by excessive positional variation of the balance wheel.

　　Maintenance precautions

　　Principles for maintaining mechanical watches:

　　1 During use, because the mainspring of an automatic watch can generally maintain a certain level of tension, taking it off the wrist and leaving it stationary will still allow it to run for over twenty-four hours.

　　2. After an automatic watch has been used for many years, its sensitivity will decrease due to the wear of automatic components, so the watch should still be swung for a certain period every night before going to bed to compensate for insufficient power

　　3 If the automatic winding mechanism fails, you can also wind the mainspring manually, though it will not fully wind. Manual winding will feel somewhat stiffer because the gears and oscillating weight of the automatic module will also rotate along with the ratchet wheel.

　　Principles for adjusting the time on a mechanical watch:

　　If a mechanical watch is left stationary for a long period, its mainspring will unwind until the watch stops. When you wish to wear it again, you must first wind the mainspring fully before setting the time. Generally, when a mechanical watch is at its lowest power reserve, the hour and minute hands may run slow or fast. Therefore, you should always wind it fully first to avoid any lack of driving power after setting the time. Even with an automatic mechanical watch, you should first manually wind it to around eighty percent capacity before adjusting the time.

　　Steps for cleaning and maintaining your mechanical watch yourself:

　　(1) Gently wipe with a soft cloth dipped in soapy water;

　　(2) Wipe with a soft cloth dipped in clean water;

　　(3) Wipe with a dry soft cloth;

　　(4) Leave to dry naturally in a well-ventilated area;

　　(5) Never send it for ultrasonic cleaning casually.