Mechanical watches do not use batteries or electronic chips.
So how can they measure time so precisely, even down to one second?
The answer lies in a mechanical system called the escapement regulating system.
This system controls how energy is released and how time is counted.
If you listen closely to a mechanical watch, you will hear a steady ticking sound.
Each tick is part of a controlled rhythm. That rhythm is what creates time measurement.
The Core: Balance Wheel and Hairspring
At the heart of every mechanical watch is the balance wheel and hairspring.
The balance wheel moves back and forth, much like a tiny swing.
The hairspring is a very thin spring attached to it. It pulls the wheel back after each movement.
This back-and-forth motion happens at a stable speed.
Because the motion is regular, it can be used to measure time accurately.
This principle is similar to a pendulum, but much smaller and faster.
How is "one second" precisely controlled?
- Adjusting the effective length of the hairspring: A shorter hairspring increases tension, causing the balance wheel to oscillate faster (making the watch run fast); a longer hairspring slows the movement down.
- Changing the mass distribution of the balance wheel: By adjusting micro-screws on the balance wheel to change the center of gravity, much like a figure skater spins faster by pulling their arms in.
The Escapement: The "Brain" of a Mechanical Watch
Without the escapement, the energy from the mainspring would be released all at once. The functions of the escapement are:
- Providing Impulses: It gives the balance wheel a small "push" just as it’s about to stop, maintaining its oscillation.
- Locking and Releasing: It prevents the gear train from spinning out of control, allowing it to advance step-by-step in sync with the rhythm of the balance wheel.
How Frequency Is Measured
Mechanical watch frequency is often written as VPH, which means Vibrations Per Hour.
A vibration is one single movement of the balance wheel in one direction.
Left is one vibration. Right is another vibration.
Most modern mechanical watches run at 28,800 VPH.
If we divide this number by the seconds in one hour:
28,800 ÷ 3,600 = 8
This means the balance wheel moves 8 times per second.
Why the Second Hand Looks Smooth
The escapement acts like a gate.
Each movement of the balance wheel releases a small amount of energy.
For a 28,800 VPH watch, the second hand actually moves 8 small steps every second.
This is why mechanical watches look smoother than quartz watches, which jump once per second.
It is not a continuous sweep, but very fast steps.
VPH and Hertz (Hz)
In physics, frequency is often measured in Hz, or cycles per second.
One full cycle equals two vibrations.
The formula is simple:
VPH = Hz × 2 × 3,600
Common examples:
- 2.5 Hz = 18,000 VPH
- 3 Hz = 21,600 VPH
- 4 Hz = 28,800 VPH (most common today)
- 5 Hz = 36,000 VPH (high-frequency movements)
What VPH Affects
Accuracy
Higher VPH means the watch divides time into smaller parts.
This helps the watch recover faster from shocks and movement.
Second-hand motion
Higher VPH creates more steps per second.
This makes the second hand look smoother.
Durability
Higher frequency also means more wear.
Parts move faster, and lubrication must be better.
Lower VPH movements wear more slowly, but are usually less precise.
Why 28,800 VPH Became the Standard
Today, 28,800 VPH is seen as a balance point.
It offers good accuracy without excessive wear.
It does not stress the movement too much.
Lubrication lasts longer.
This is why many modern mechanical watches use this frequency.
Conclusion
A mechanical watch measures time through motion, not electronics.Its accuracy comes from rhythm, balance, and controlled energy release.
VPH is the heartbeat of that system.
