Mechanical watches represent one of mankind's most exquisite feats of engineering, where the macroscopic world meets microscopic precision. Unlike quartz analogues, which rely on electrical impulses from the crystal, mechanics operate solely on the basis of accumulated potential energy, converted into uniform movement of the hands. This process does not require batteries, but does require periodic winding, creating a unique bond between the wearer and the device, making wearing the watch a ritual.
The heart of any such mechanism is a complex system of gears, levers and springs enclosed in a housing. The working principle of a mechanical watch is based on a strict sequence of energy transfer from the source to the controller. Even small variations in helix tension or tooth lubrication can result in significant errors, which is why every component is manufactured to micron precision. Understanding this inner workings allows us not only to appreciate the skill of watchmakers of the past, but also to correctly operate modern expensive models.
Externally, the clock appears to be a monolithic object showing time, but inside it a constant dynamic tension unfolds. Energy is spent evenly, ensuring a stable movement of the second hand, which is often called the “pulse” of the mechanism. It is this continuity and smoothness of movement that distinguishes true mechanics from the discrete ticking of electronics, making each tick a unique event in the operation of a complex system.
Power source: mainspring and drum
It all starts with the energy source, which in classic mechanical watches is mainspring. This is a long strip of special steel or modern alloys, rolled into a tight spiral and placed in a cylindrical body called a barrel. When you turn the crown, you twist this spring, creating enormous tension inside it. It is this accumulated potential energy will power the entire mechanism for the next 24, 48 or even 80 hours.
It is important to understand that the force with which a spring tends to unwind is not constant. When fully wound up, it is maximum, and as the power reserve is depleted, it weakens. To compensate for this unevenness in expensive calibers, a system is used maltese cross or fusée, which cuts off the extreme values of the tension, leaving only the middle, most stable part of the spring stroke for work. This allows the watch to remain highly accurate no matter when you last wound it.
⚠️ Warning: Never use excessive force when winding your watch by hand. Modern mechanisms often have a friction device that slips when fully wound, but older or simpler models can damage the gear teeth or break the spring itself.
The winding drum is connected to the central axis through a system of wheels, transmitting torque further along the chain. The rate of energy release is controlled not by the force of the spring, but by the brake - the stroke control, which will be discussed below. Without this “brake” the spring would discharge in a split second with a characteristic whistle.
If your hand-wound watch has stopped, before setting the time, gently turn the crown clockwise about 20-30 turns to restart the movement and distribute the lubricant.
Power transmission: wheel system
After the energy is released from the drum, it enters wheel system (or wheeled train). This is a cascade of interconnected gears of various diameters, each of which rotates at a certain speed. The task of this system is not only to transmit torque, but also to reduce the rotation speed to the required minimum so that the hands move at the required frequency.
The first wheel meshed with the drum makes one revolution in approximately 6-12 hours (depending on the caliber). Subsequent gears rotate faster, transmitting the force further. The central wheel typically makes one full revolution every 60 minutes and directly controls minute hand. The second wheel, in turn, rotates every 60 seconds, driving the second clock.
- 🔗 Grip accuracy: Gear teeth have a special profile (involute or cycloidal), which minimizes friction and wear when transmitting force.
- ⚙️ Tribs and wheels: The smaller gear (tribe) is mounted on the larger axis, creating compact rotation transmission units.
- ⏱ Speed differentiation: The system allows one spring to simultaneously move the hour, minute and second hands at different speeds.
This entire system must operate with minimal resistance. To do this, the gear axles rest on rubies - synthetic stones with an extremely low coefficient of friction. If the gears were to rotate in ordinary metal holes, friction would quickly stop the mechanism or cause it to collapse.
Why rubies?
Synthetic ruby (aluminum oxide) has a hardness of 9 on the Mohs scale. This makes it virtually impervious to abrasion from metal axes, ensuring stable watch operation for decades without loss of accuracy.
The heartbeat of the mechanism: balance and spiral
The key element that turns a continuous flow of energy into measurable periods of time is speed controller. In modern mechanical watches, this is an oscillator consisting of a balance (flywheel) and a hairspring. The balance is a heavy wheel that, under the action of a spiral, makes oscillatory movements back and forth.
The principle of operation resembles the operation of a pendulum in a grandfather clock, but in miniature and in a horizontal plane. The spiral compresses, expands and contracts again, causing the balance to rotate in one direction or the other. The frequency of these vibrations determines the accuracy of the move. Standard values are 18,000, 21,600, 28,800 or even 36,000 vibrations per hour (vph).
The higher the oscillation frequency, the more accurate the watch, since it recovers faster from external influences (shocks, shakes). However, high frequency requires better lubrication and increases wear of parts. The speed is adjusted by changing the effective length of the spiral using a special lever (thermometer) or microscrews on the balance itself.
Trigger: anchor and stroke
If the balance is a metronome, then the trigger (anchor) is the hand that moves the metronome hands and gives a “kick” to the pendulum so that it does not stop. Anchor descent is a bridge between the continuous rotation of the wheel system and the intermittent oscillations of the balance. It performs two critical functions: it locks the wheel system and periodically pushes the balance.
The process goes like this: the tooth of the escape wheel rests against the pallet of the anchor fork, blocking the rotation of the entire system. At the moment when the balance turns the anchor by inertia, the fork releases the tooth. The wheel turns one tooth, but immediately hits another fork pallet. This shock is transmitted through the fork to the balance (via the impulse stone), recharging it with energy for the next swing.
It is this cycle of blocking-releasing-impulse that we hear like a clock ticking. The sound occurs when the tooth hits the pallet. The quality of these parts, their polishing and geometry directly affect the amplitude of the balance oscillations and, consequently, the accuracy of the movement.
| Component | Function | Material |
|---|---|---|
| escape wheel | Transferring energy to the anchor | Beryllium bronze |
| Anchor plug | Lock and impulse | Steel |
| Pallets | Contact with teeth | Synthetic ruby |
| Pulse Stone | Transferring impulse to balance | Synthetic ruby |
Automatic winding: freedom from the crown
In automatic mechanical watches (vending machines) the operating principle is complemented by a winding system based on the movements of the owner’s hand. The main element here is eccentric weight (rotor), which rotates freely on a central axis under the influence of gravity. Any movement of the wrist causes the rotor to vibrate.
Through a gearbox system (often using an overrunning clutch), the rotation of the rotor is transmitted to the winding drum, tightening the spring. An overrunning clutch is necessary so that when the rotor rotates in the opposite direction, the spring does not unwind and the mechanism continues to work. Modern systems may have two rotors or use ball bearings to improve efficiency.
⚠️ Attention: If an automatic watch is left idle for a long time, the spring may become completely relaxed. Before wearing for the first time or after a long break, they must be wound manually through the crown by 20-30 turns to start the mechanism and ensure a power reserve.
There are also systems where the rotor rotates in one direction only, or (double-sided) where the winding goes in both directions. The effectiveness of automatic winding depends on the activity of the owner: office work may not be active enough to fully wind, while active walking will provide the watch with plenty of energy.
☑️ Checking the status of your automatic watch
Display and additional functions
The basic principle of watch operation - showing time - is implemented through a system of hands and dial. However, mechanics makes it possible to implement highly complex functions called complications. Date, day of the week, moon phases, chronograph, tourbillon - all these are additional mechanisms built into the base caliber.
The most common is the date function. The date wheel rotates once every 24 hours and switches the number disk. The switching mechanism usually operates quickly at midnight, storing energy for several hours. A chronograph is an independent stopwatch mechanism that requires a separate system of wheels and control buttons that do not affect the main passage of time.
The tourbillon, invented by Abraham Louis Breguet, is a device in which the entire escapement (balance, hairspring, anchor) is placed in a rotating cage. This compensates for the effect of gravity on the accuracy of the watch at different vertical positions. Although the influence of gravity is minimal in modern wristwatches, the tourbillon remains a symbol of fine watchmaking.
Complex functions (complications) increase the number of parts in the mechanism several times, which requires more frequent maintenance and increases the risk of breakage due to impacts.
What is power reserve and what does it depend on?
The power reserve is the amount of time a mechanical watch can operate after being fully wound. It depends on the length and quality of the spring, the amount of energy consumed by the mechanism (complications “eat” more), and the efficiency of force transmission. The standard is 40-48 hours, modern calibers can reach 7-10 days.
Why can mechanical watches be fast or slow?
The main reasons: changes in the viscosity of the lubricant due to temperature changes, magnetization of the spiral (speeds up), wear of parts, shocks, or simply the need for adjustment. The normal error is considered to be from -10 to +20 seconds per day.
Is shaking a watch harmful to mechanics?
Sudden shocks and vibrations are dangerous to the balance and axle. However, moderate shaking when worn on the hand is beneficial for automatic winding. It is strictly forbidden to expose mechanics to impacts on hard surfaces or vibrations from power tools.
Do mechanical watches need to be lubricated?
On your own - absolutely not. Lubrication of a watch is a high-tech process that requires complete disassembly, ultrasonic cleaning and the application of microscopic doses of special oils to precisely defined points under a microscope.
The magnetic field is a hidden enemy
Modern hairspring alloys (such as Parachrom from Rolex or Si14 from Patek Philippe) are paramagnetic and resistant to fields of up to 1000 Gauss and higher. Old watches can become magnetized by speakers, tablets, and cases with magnets.