Portal: Watch Knowledge

The balance wheel is the heart of the oscillating system of a compact portable timepiece such as a wrist or pocket watch. The vibration of the balance wheel is used to measure time and is one of the main specifications of a movement. The balance wheel produces a temporally-defined movement, rotating back and forth, which is then transmitted through the gear train of the watch movement into a movement of the hands. It serves the same function as the pendulum in a clock, but is much more compact and works largely independent of the position of the watch.

The balance wheel was developed by Christiaan Huygens, and he was granted a French patent in 1675 for this purpose.

Because the balance wheel is constantly in motion, it can easily be damaged by shocks transmitted through the case. For this reason, most modern movements include a form of shock protection. The bearing stone is set in a spring which can move in response to a shock, temporarily interrupting the wheel but protecting the journals from damage. See for example Kif and Incabloc …

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