How a Mechanical Watch Works


Movement Structure Chapters:

If the movement is divided into two structures, the active drive train and the auxiliary drive train, the active drive train is the main line, and the auxiliary drive train is connected to the main drive train and integrated into it.


The active drive train also includes four systems, namely the prime mover, the transmission wheel train, the escapement and the vibration mechanism.

All power is sent from the original system spring to the center wheel, the over wheel, the second wheel, the escape wheel, the clip, and then to the balance wheel, and then the balance reaction force to the escapement fork to restore its previous position, so the whole process can be repeated. To put it simply, the energy stored in the motive system is transmitted to the vibration system through the escapement and lasts for a long period of time. At the same time, the vibration system is released to the escapement mechanism and transmitted to the pointer mechanism to indicate the time.

The original motion system consists of a barrel, a strip cover, a spring, and a spring roller. The function is to store the elastic potential energy generated by tightening the spring as energy. In the operation of the movement, the spring energy releases the elastic energy to the mechanical energy, thereby driving the wheel train to rotate, and maintaining the vibration system to periodically replenish the vibration without attenuating the vibration, and at the same time driving the movement of the display system and the additional mechanism.

The transmission wheel train is mainly composed of a center wheel (two wheels), an over wheel (three wheels), and a second wheel (four wheels). To put it bluntly, it is a mechanical transmission that uses gear teeth to mesh with each other to transmit power and motion. The movement’s transmission wheel train is divided into two types, the positive center transmission form and the off-center transmission form. The center wheel (two wheels) is determined by the position of the main plate of the movement.

The function of the escapement system is to periodically and regularly replenish the energy transmitted by the train to the vibration system to maintain it as a non-attenuating vibration. In addition, it accurately calculates the number of vibrations of the vibration system. The escape wheel controls the display system through the gears such as the second wheel to achieve the purpose of measuring time.

The vibration system is a balance spring system. If the time (vibration period) required for the balance spring vibration system to complete a full vibration is determined and the number of vibrations is calculated, then the time experienced by the vibration is equal to the vibration period multiplied. The number of vibrations, that is, time = vibration period × number of vibrations. The vibration system and the escapement system are also referred to as speed control systems.

The auxiliary drive train includes a display system and a winding hand system.

The display system is interfaced with and integrated into the active drive train, including the most basic display trains, such as the hour wheel, the minute wheel and the second wheel, as well as the cross wheel responsible for converting the rotational speed. Since the transmission wheel train is divided into a positive center transmission form and a partial center transmission form. Therefore, the display system transmission mode is also divided into a positive center display system and a partial center display system.

The wound plucking needle system can be separately understood. The wound is to transfer energy to the prime mover, and the plucking pin is the mechanism for cocking the pointer. This mechanism includes not only the movement of the hour and minute hands, but also the display parts of the additional mechanism carried by the drive core, such as the calendar and the weekly calendar. By the crown, the stem, the vertical wheel, the clutch wheel, the clutch lever, the clutch lever spring, the pull gear, the compression spring, the setting wheel, the span wheel, the hour wheel, the minute wheel, the large steel wheel, the small steel wheel, the pawl, the pawl spring and other components. The automatic winding is composed of a heavy hammer, a heavy hammer support, an eccentric shaft, a ball, an automatic rocking plate, a ratchet, a pawl, and an automatic upper plate.

The basic structure of the movement should have a preliminary understanding. In the next section we will focus on the key parts and principles of the various structures of the movement.

Everything is inseparable from the foundation. I always think that the watch movement is the same. For example, Patek Philippe’s basic movement cal.324, based on the addition of various functional modules, has created various functions based on cal.324 or complex movements (such as Cal.324 S IRM QA LU, is the addition of the power reserve, perpetual calendar window date display and moon phase). Therefore, a basic movement is very important for a watchmaking brand, and a basic movement as thin as possible and small means that it can add more functions.

The basic movements of various models from various brands have different characteristics, but the basic structural principles are similar. The energy is stored in the spring by a winding or an automatic pendulum, and the energy is transmitted to the oscillating system through the escapement for a long working period. At the same time, the oscillating system is released to the constant velocity movement of the escapement and transmitted to the pointer mechanism to indicate the time.

Recently, I got a few of the watches with the calendar display function equipped with the automatic original movement, the movement reference is not mentioned, let us have a glimpse.

Tool Chapters:


Let’s first talk about the disassembly tool. First, you need a special magnifying glass. Since the parts of the watch are exquisite, so the purpose of the magnifier is to make each parts be visible to prevent damage during disassembly and assembly. It is usually necessary to prepare 3 to 12 times a magnifying glass of different magnifications, but this time I only disassembled the parts, so a low multiple prepared is enough.

Movement Fixed Base

The fixed seat is to fix movement, making it easy to disassemble. You need to lock gently, don’t use too much force to avoid hurting the board.

Special Screwdriver

The whole set of special screwdrivers will be available on the work table of each watchmaker. There are different combinations of 10, 9 and bulk. You can replace the blade by loosening the screw fixing hole on the screwdriver. Each knife has a color to distinguish the specifications, and the outer circle number represents the diameter of the knife. Use the size of the screw first and select the appropriate size, so as not to damage the screw cap or accidentally slip the hand to scratch the board.

Antimagnetic Tweezer

The tamper-resistant tweezers are also necessary. When the parts are gripped, the parts are protected from magnetism. Usually 2 to 3 pieces are enough. Thicker tips are usually used to pick up general parts such as movements, splints, screws, gears, etc. Small parts are usually used with thinner tips. Do not use too much force. When picking up parts, do not pinch the plane. It is best to find the appropriate place to pick it in a vertical way to prevent the parts from being scratched by improper force.

I got a separate movement this time, and there is no hands. Therefore, there are fewer steps in disassembly, no need to open the bottom cover, and there is no need to pull the pointer. But let’s introduce it here.

Universal Watch Opener

Watch Hands Puller

The opener can be used to open the screw-in bottom cover, adjust the opener to the appropriate size of the watch, press it and rotate it to the left to open the back cover. It is better to use it with the watch fixed base. The hand puller is used to remove the pointer, and there are also unused hand pullers depending on the model.