The fine spring that returns a mechanical watch’s balance wheel toward its resting position and helps determine its oscillation rate.
The balance spring, also called a hairspring, works with the balance wheel to regulate a mechanical watch. As the wheel swings away from its resting position, the spring supplies the restoring force that brings it back. The spring’s active length and the balance wheel’s moment of inertia determine the duration of each oscillation. In movements fitted with a regulator, changing the active spring length allows the rate to be adjusted. Isochronism describes the aim of keeping that rate consistent as the width of the balance’s swing changes, including as the watch’s stored energy falls.
In job listings
The balance spring is more likely to be discussed at the bench than in a listing. A watchmaker works on it during regulation and repair, and a watch advisor may mention it when explaining how a movement keeps time. Search local jobs for “watchmaker”.
