How it Works: Balance Wheel and Escapement
In recent decades, the “ticking of the clock” has become an expression which more or less looks back to the past or is, if the function is activated, heard on our electronic timepiece, be it smart or not. Nevertheless, mechanical timepieces today continue to tick on the wrists of many horological enthusiasts and that is due to technology which has hardly changed in the three centuries since Christiaan Huygens presented his invention at the French Royal Academy: the oscillator with an integrated hairspring, called a balance wheel.
Almost a century after Huygens introduced the balance wheel, the English watchmaker Thomas Mudge introduced the world to the so-called Swiss lever escapement, which right up until the present day has performed the role of the wristwatch “brain” – it controls the release of energy stored in the mainspring and basically ensures that the mechanism keeps ticking at the same speed. From the time of their inventions until today, the watchmaking industry has developed and presented a fair number of balance wheel and escapement variants with the use of modern materials. Still, the mechanics of functioning practically hasn’t changed through these several centuries:
Almost all similar mechanisms have been developed on the basis of Huygens’ invention: the spirally wound spring in the balance wheel.
The traditional balance wheel and escapement are usually assembled from approximately 30 metal parts
The traditional balance wheel and escapement are usually assembled from approximately 30 metal parts, which have to be connected so that their expansion due to changes in temperature does not influence the functioning of the system, they have to be as resistant as possible to influences of the magnetic field, and above all, the contacts between different moving parts have to be appropriately lubricated to prevent energy loss. Modern horology overcomes these obstacles with the use of new metal alloys resistant to temperature changes and magnetic fields. Nevertheless, challenges, involving lubricants, component parts wear, and energy loss on account of numerous movable parts and their relatively high weight, remain in the form of limitations to the power reserve, mechanism precision, and the need for regular servicing, setting, replacement or lubrication of moving parts.
Many watchmakers have been using silicon for certain parts of their mechanisms.
More interesting alternatives to the traditional materials include Glucidur, a compound of copper, beryllium, and steel; highly corrosion-resistant tantalum; and various mixtures of ceramics and carbon, for the balance wheel spring, for example, Nivarox, a mixture of steel and nickel, or the practically indestructible material Parachrom used by Rolex. Various surface treatments are also very interesting since they improve the properties of the metal. Furthermore, for almost a decade now, many watchmakers have been using silicon for certain parts of their mechanisms for it has been established as a light, durable, antimagnetic material extremely resistant to temperature changes which, in addition to everything else, does not require the use of lubricants. In certain models, Rolex and Tudor use it for the balance wheel spring, while it has also replaced metal in the production of escapements in this year’s Panerai LAB-ID and Breitling’ Superocean Heritage Chronoworks. Regardless of how well a classical movement is made, from which material the balance wheel spring or escapement are made, the limitations involving accuracy and energy inefficiency of the base still remain.
After more than three centuries of use of the classical balance wheel and its variations, a more noticeable step in the development of the “brain mechanism” has been made by the watchmaker Zenith, who have replaced the oscillator made from about 30 parts with one made from only one piece of monocrystalline silicon.
This eliminated the need for lubrication and above all achieved extraordinary progress in temperature and magnetic resistance, energy efficiency, and precision.
The new oscillator in the El Primero Defy mechanism can boast an over 10% improved power reserve despite the three-times higher oscillation frequency amounting to 15Hz. With a classical oscillator the accuracy in the second half of the power reserves of the mechanisms drastically decreases, while Zenith in their new system guarantee equal punctuality through 95% of power reserve. Moreover, equal punctuality does not mean that it “only” meets the COSC standards – Zenith promises +/- 0.5s of daily deviation, which in comparison to daily deviations of +/- 2s with the leading names in the industry, sounds simply amazing.
In recent decades, the world of traditional horology has proven that it evolves and moves in its own rhythm and especially that it strives towards tested and therefore reliable solutions which are, in their pursuit of mechanical perfection, continuously improved and upgraded. The same goes for the brains of timepieces – the balance wheel and escapement.
This year these have experienced changes that promise exceptional progress and open many possibilities in the direction of higher efficiency, and primarily of punctuality of mechanical wristwatches.