How Does a Watch Work? The Complete Guide To All Types Of Movement

Guides and Insights

Edoardo Polverelli

DATE

22 October 2024

The mechanical movement

piaget self-winding movement with micro rotor — Example of a watch with a self-winding movement – Credits: Swiss Watch Brands

The mechanical movement is the first type we are going to analyze today, and it is also the oldest, as it was initially used in bell towers to mark the daily routine of cities. Later, it was miniaturized more and more and placed inside pocket watches first, and, later, in wristwatches. The operation of this movement, on the surface appears very simple, but its refinement required several centuries of study.

The operation of the mechanical movement

Speaking of a mechanical movement, we need to make, first of all, a distinction in the way the watch can be wound. In fact, we speak of manual winding when the mainspring is compressed only by turning the crown at 3 o’clock, while with winding automatic we mean the winding of the movement also by the movement of the wrist, thanks to an oscillating weight placed on the movement.

components of a mechanical watch movement — Barrel – Credits: Review Watches

The drive phase begins with the barrel, which is a container inside which we find the mainspring. When we wind our watch by turning the crown at 3 o’clock, in the case of a hand-wound caliber, or through the movement of the wrist that drives the oscillating mass, we are in fact winding this spring that stores elastic potential energy, which will be released slowly by transforming into kinetic energy, thanks to the balance wheel (gold wheel in the next photo) that regulates its discharge.

Balance with anchor and escapement of a mechanical watch movement. — Balance with Anchor and Escapement – Credits: Watch Review

The spring inside the barrel, through a gear train, then transfers the force to the balance wheel, which will rotate left and right in a balanced, alternating manner thanks to a spiral integrated with it. Attached to the balance wheel is a component called an anchor (T-shaped piece in the photo above), which interacts with the escapement wheel (wheel in purple in the upper photo) allowing the energy to be released in a regular manner. This process is what produces the watch’s characteristic “tick-tock.” Each swing of the balance wheel allows the gear train to advance one tooth, transforming the potential energy of the spring into regulated motion.

You know the alternations/hour found in the data sheets of watches? Here, these indicate the frequency with which the balance moves, so an alternation of 28,800 alternations/hour means that the balance moves, left and right, about 28,000 times per hour.

Mechanical watch components – Credits: time marker

Through the “time train,” i.e., a series of gears connecting the barrel to the seconds, minutes, and hours wheel, energy is distributed and the speed of the wheels is reduced. Since the second wheel makes one revolution every minute, the reduction ratio must be such that the minute wheel makes one full revolution every 60 minutes (1 hour).

Suppose the seconds wheel has 60 teeth and the wheel connected to the minute shaft has 10 teeth. The ratio will be 60:10 = 6:1. This means that for every 6 revolutions of the seconds wheel, the minutes wheel makes one revolution. Similarly, the hour wheel is connected to the minute wheel through a 12:1 ratio, so that it completes one full revolution every 12 hours.

The oscillating mass of a mechanical movement

Self-winding mechanical movement – Credits: Patek Philippe

It is important to mention the oscillating weight as it was a crucial revolution, and looking at the movements of the most emblazoned maisons, we notice that this is very often made of gold: why?

When it comes to, for example, Patek Philippe, this aspect immediately jumps out at you when you look at the case back, as attention to detail is what characterizes the Geneva-based maison. This is based on certain physical concepts, such as the fact that gold is about 3 times denser than ordinary steel.

This causes the oscillating mass to accumulate more kinetic energy when it moves. In other words, when the wrist moves, the gold mass has greater inertia and can rotate with more force, thus transferring more energy to the watch winding system. In addition, this greater heaviness allows the mass to oscillate even with small movements, contributing to the efficiency of the mechanism.

The quartz movement

It is well known that the watchmaking industry faced a period of severe crisis, which challenged the maisons during the 1970s. This period is referred to as the quartz crisis, as the Swiss manufacturing and traditional industry, had to contend with the low production costs and high reliability of battery-powered Japanese movements, which had made the watch accessible to everyone.

The operation of the quartz movement

80' Seiko advertisement depicting a seiko watch with quartz movement — 80′ Seiko advertisement – Credits: Seiko 1881 Forum Group

If in the mechanical movement what powers the mechanism is a spring, in the quartz movement we find a quartz crystal that, when stimulated electrically, always vibrates at the same frequency. This vibration is visible through the second hand. Let’s explain it further.

Quartz is a mineral, which has a property called piezoelectricity, that is, when stimulated electrically, this begins to oscillate with a precise and stable frequency. Clearly inside the watches is a small amount of this material, which is cut and shaped to vibrate at the frequency of 32,768 Hz (oscillations per second) usually.

To stimulate the crystal, a constant-voltage battery is needed to allow the quartz to oscillate continuously.

Components of a quartz movement – Credits: Bonaldi

Obviously, the second hand, visible on the dial, will not be able to make 32,768 revolutions per second. This brings into play the electrical circuitry present in this type of movement, which divides the signal by 2 repeatedly (15 times) until a constant frequency of 1 Hz, or one pulse per second, is obtained. This pulse is sent to a stepper motor, which drives the gears below the dial to make the hands move.

A crucial aspect of this movement, is the fact that it is not affected by external factors such as temperature or humidity, so under any conditions, the quartz vibrates at the same frequency, making these types of watches very reliable and long-lasting, without the need for maintenance as is the case with mechanical movements.

The tuning fork movement

Bulova Accutron 1970s advertisement with quartz movement — 1970s Bulova Accutron commercial – Credits: Watches and Passions

Introduced before quartz, and first introduced in 1960 by Bulova with the Accutron model, the tuning fork movement was the first power supply as an alternative to mechanical power supply, characterized by high reliability and precision.

This new type of power supply, was so successful in those years because it was the first to give a new solution as a replacement for the classic mechanical gauge, which, despite considerable improvements over the years, possessed a significant daily deviation in accuracy.

The operation of tuning fork movement

Bulova Accutron with tuning fork movement — Bulova Accutron – Credits: Maurence Monkey

The operation of this movement is very similar to the quartz movement; in fact, here too we have a component that, when stimulated electrically, vibrates at a constant frequency (32,768 Hz).

I am talking about the tuning fork, a U-shaped metal element, which is stressed by an electromagnetic field produced by an electromagnet powered by a battery. This vibration is attenuated and reduced by a transducer, which converts the vibration into electrical pulses.

Electrical impulses generated by the transducer are sent to a stepper motor. This type of motor converts electrical energy into mechanical motion and advances the gears of the time train, the mechanism that moves the hands. In this case, the movement we will see on the dial, will be very similar to that of a mechanical watch in that the second hand performs a continuous motion, without stopping.

Bulova Accutron components – Credits: Watch repairs UK

The main characteristics of this movement are reliability and precision (the deviation is negligible, we are talking about a few seconds per month), two peculiarities that made it popular all over the world, before the arrival of quartz.

The Quartz VS Diapason movement: the differences

On the surface, these two movements may look very similar, but there are several features that differentiate them.

In the quartz movement we have seen that there is an electrical circuit that reduces the frequency of oscillation of the ore, while in the tuning fork movement we have a transducer, that is, a component that allows one type of energy to be converted into another. We can summarize by saying that in quartz we reduce the frequency digitally, while in tuning forks we reduce it analogically.

Another difference is the way the second hands “beat” on the dial. In fact, in the former case this moves in pulses of 1 second, while in the latter we find a linear movement, as if the watch were mechanical.

Over the years, the quartz movement, because of its lower production costs and simplicity of components, has managed to creep more into the market, now becoming a standard for most watches that do not have mechanical gauges.

The Spring Drive movement

Another type of power supply that has been much talked about, because of its high complexity from an engineering point of view, is the Spring Drive movement, a special type of movement patented by Grand Seiko that we can say is a hybrid of the two just mentioned above.

The Spring Drive movement represents a unique combination of traditional mechanical technology and electronic regulation, providing superior precision to conventional mechanical watches. Launched in 1999, it represents a fusion of the beauty and tradition of mechanical watches and the precision of quartz watches, creating a system that operates without a battery but with a quartz regulator.

Operation begins with a driving spring, similar to that in mechanical watches, that stores energy and gradually releases it. This energy rotates a series of gears, but instead of using a traditional escapement to regulate the movement, the Spring Drive uses the Tri-Synchro Regulator. This system controls three forms of energy:

Mechanical energy from the driving spring;
Electrical energy generated by a magnetic coil that converts the movement of gears into electrical impulses;
Electromagnetic energy to control the speed of the escape wheel by means of an electromagnetic brake.

Tri-Synchro Regulator – Credits: Grand Seiko

The unwinding energy of the spring causes the rocker arm to move, generating electricity in the coil that powers the oscillator crystal and the integrated circuit. The integrated circuit compares the accuracy of the electrical signals generated by the oscillator crystal with the rotational speed of the balance wheel, and on this basis controls the rotational speed of the balance wheel by applying the electromagnetic brake where necessary.

This is precisely what is most fascinating, namely the fact that there is no friction at the level of the balance, making this type of movement extremely smooth and efficient. In fact, this process ensures extremely high precision, with a tolerance of ±1 second per day.

Spring Drive movement components – Credits: The Seiko Guy

One of the distinctive elements of the Spring Drive movement is the linear movement of the second hand. Unlike mechanical watches, in which the second hand moves in small jerks, the hand in Spring Drive watches runs continuously and smoothly, with no visible interruption.

Spring Drive movement can be either automatic or manual.

Other types of movement

The Solar Movement

The solar movement uses a photovoltaic panel located under the dial to convert light (solar or artificial) into electricity. The energy is then stored in a rechargeable battery, which powers the watch even when there is no light for extended periods. This system, like Citizen’sEco-Drive, eliminates the need to replace the battery. It is a technology that ensures great autonomy and reliability.

Spring Drive movement components with eco drive movement — Citizen Eco-Drive commercial – Credits: Citizen

The Kinetic movement

The Kinetic movement, introduced by Seiko, generates power through a rotor that moves with the wrist. The rotor powers a generator that produces electricity, which is stored in a rechargeable battery or capacitor. This system combines automatic winding, typical of mechanical watches, with the precision of a quartz movement. The Kinetic offers long-term autonomy without requiring the replacement of a conventional battery.