A mechanical watch consists of a movement and external components. The movement includes the transmission system, power system, winding and setting system, escapement and regulating system, and hand system. The movement parts are assembled together by a base plate with screws; the external components consist of the case, dial, hands, and strap, etc.

1. Transmission System

The transmission system consists of the center wheel, intermediate wheel, seconds wheel, escape wheel, etc. It is a set of transmission gears that transmit power to the escape wheel and drives the hand mechanism.

The transmission system of a mechanical watch connects the power system and the regulating mechanism, forming a complete main transmission chain. The smoothness and stability of this chain directly determine the accuracy of the mechanical watch movement.

2. Power System

The structure of the power system consists of the barrel, arbor, and mainspring, etc. It is the energy source of the watch, supplementing the resistance consumption of the entire mechanism, driving the rotation of the gears, and maintaining the oscillation of the balance wheel.

The source of the main transmission chain in a mechanical watch movement—the power system—is defined by its internal storage of the elastic element mainspring, i.e., storing elastic potential energy. This depends on the length and thickness of the mainspring; its elastic potential energy determines the duration of the mechanical watch's running time. After the mainspring converts its stored elastic potential energy into mechanical energy, it provides the original energy for the mechanical watch. When the mainspring's stored elastic potential energy is completely released, the mechanical watch loses its energy supply and stops running.

3. Winding and Setting System

The winding system is manually wound using the crown on the outside of the case. The setting is similar. Whether it is a rocker-type or a clutch-type winding and setting mechanism, gear transmission is a widely used transmission type. The transmission of the setting wheel and the small steel wheel, and the transmission of the clutch wheel and setting wheel are specific forms of gear transmission.

In a mechanical watch, the winding transmission directly uses two cylindrical gears—the setting wheel and the small steel wheel—to transmit motion between vertically intersecting axes. In the hand-setting transmission, a cylindrical gear (setting wheel) and an end-face gear (clutch wheel) are used to transmit motion between vertically intersecting axes. The main requirements for these two transmissions are stable operation and flexible transmission, which depend on the mutual configuration of the meshing gears. Increasing the meshing depth can improve operational stability, i.e., it is not easy to cause disengagement. Excessive meshing may make the transmission inflexible or even cause jamming. Therefore, when repairing or selecting parts for the winding and setting mechanism, attention should be paid to whether the correct meshing of the gears is affected.

4. Escapement and Regulating System

The escapement and regulating system consists of two parts: the escapement mechanism and the regulating mechanism. The regulating mechanism relies on the periodic oscillation of the balance wheel and hairspring to maintain the precise and regular continuous movement of the escapement mechanism, thereby achieving the regulating function. It includes the balance wheel assembly, hairspring assembly, regulator, and adjusting pins, etc. The escapement mechanism consists of the escape wheel, pallet fork, double disc, etc., which transmits energy to the regulating mechanism and measures the number of oscillations.

5. Hand System

The hand mechanism includes the hour wheel, minute wheel, intermediate wheel components, dial components, hour hand, minute hand, and seconds hand, etc. The minute wheel is the driving wheel, which drives the hour wheel to rotate through the intermediate wheel and intermediate wheel arbor. The hour wheel slides on the minute wheel tube. A "ingot-shaped" hour wheel spring is installed between the hour wheel and the dial, or between the hour wheel and the date wheel. With the cooperation of the center wheel tube and the minute wheel in the movement transmission, the center wheel rotates and drives the minute wheel to rotate together by friction. In the differential wheel type three-wheel output transmission, the elastic part of the minute wheel plate is embedded in the groove of the minute wheel, forming the components of the minute wheel.