THE SEAHOLM® LIBRARY
The truth is that the most stable regulating organ – not the fastest – will enable the watch to keep more accurate time.
Marketing material for the modern mechanical watch almost always includes a description of the the movement’s frequency. Whether it is described in terms of Hertz (Hz) or vibrations/beats per hour (vph/bph), you will have likely grown familiar with frequencies that range between 2.5 and 5 Hz (18,000 to 36,000 vph).
You may have even sensed that the higher the frequency, the more accurate a movement gets.
But is this entirely true?
If higher frequency really delivers better performance, why do watches still exist that run below 5 Hz (36,000 vph)? And what happens when you turn it up to 10 Hz or even beyond?
In this post, I try to dispel some of the myths and clarify some of the truths about high-frequency mechanical movements. But first: the basics.
What is frequency?
Frequency is described in the Merriam-Webster dictionary as “the number of repetitions of a periodic process in a unit of time.” The word applies to alternating current or to oscillations. An oscillation commonly describes a wave of sound or electromagnetism, but this is also where watch frequency comes in.
A mechanical watch movement features a power source (the mainspring), transmission (the gear train), and regulation (the escapement, balance wheel, and hairspring). The power flows from the mainspring, via the transmission, to the escape wheel, and it is through the oscillations of the balance wheel that the power is ultimately and precisely expelled and the movement’s frequency is manifested.
Each time the balance wheel swings in a given direction its roller jewel knocks the lever, unlocking the escape wheel. The escape wheel delivers an impulse to the balance via the lever, powering a new vibration, before locking once more.
This process takes place several times per second in a mechanical wristwatch.
As important as it is to the movement, the “breathing” of the hairspring and the frantic stuttering of the lever and escape wheel is equally mesmerizing to behold in action.
When we describe a movement as having a frequency of 4 Hz or 28,800 vph, we describe the same phenomenon but in different ways. The balance wheel, in conjunction with a Swiss lever escapement, vibrates in two directions: it rotates clockwise until the hairspring causes it to stop and swing counterclockwise.
This double vibration equals one oscillation; a 4 Hz balance will do this four times per second.
Because there are two vibrations for every oscillation, a 4 Hz balance will vibrate eight times per second, equaling 480 times per minute, which is equivalent to 28,800 times per hour.
Marketing material for the modern mechanical watch almost always includes a description of the the movement’s frequency. Whether it is described in terms of Hertz (Hz) or vibrations/beats per hour (vph/bph), you will have likely grown familiar with frequencies that range between 2.5 and 5 Hz (18,000 to 36,000 vph).
You may have even sensed that the higher the frequency, the more accurate a movement gets.
But is this entirely true?
If higher frequency really delivers better performance, why do watches still exist that run below 5 Hz (36,000 vph)? And what happens when you turn it up to 10 Hz or even beyond? In this post, I try to dispel some of the myths and clarify some of the truths about high-frequency mechanical movements. But first: the basics.
What is frequency?
Frequency is described in the Merriam-Webster dictionary as “the number of repetitions of a periodic process in a unit of time.” The word applies to alternating current or to oscillations. An oscillation commonly describes a wave of sound or electromagnetism, but this is also where watch frequency comes in.
A mechanical watch movement features a power source (the mainspring), transmission (the gear train), and regulation (the escapement, balance wheel, and hairspring). The power flows from the mainspring, via the transmission, to the escape wheel, and it is through the oscillations of the balance wheel that the power is ultimately and precisely expelled and the movement’s frequency is manifested.
Each time the balance wheel swings in a given direction its roller jewel knocks the lever, unlocking the escape wheel. The escape wheel delivers an impulse to the balance via the lever, powering a new vibration, before locking once more. This process takes place several times per second in a mechanical wristwatch.
As important as it is to the movement, the “breathing” of the hairspring and the frantic stuttering of the lever and escape wheel is equally mesmerizing to behold in action.
When we describe a movement as having a frequency of 4 Hz or 28,800 vph, we describe the same phenomenon but in different ways. The balance wheel, in conjunction with a Swiss lever escapement, vibrates in two directions: it rotates clockwise until the hairspring causes it to stop and swing counterclockwise.
This double vibration equals one oscillation; a 4 Hz balance will do this four times per second.
Because there are two vibrations for every oscillation, a 4 Hz balance will vibrate eight times per second, equaling 480 times per minute, which is equivalent to 28,800 times per hour.