Component record · Regulation
Regulator
VerifiedAn adjustable index, typically a curb-pin carrier arm, that lets the effective free length of the balance spring be shortened or lengthened.
What it does
Provides fine rate adjustment (faster/slower) without changing the balance or spring themselves.
How it works
Moving the regulator arm slides a pair of curb pins along the balance spring's outer coils. Moving the pins toward the stud effectively shortens the active length of the spring, stiffening its action and speeding the watch; moving them away lengthens the active spring and slows the watch.
Because curb pins introduce some friction and can distort the ideal concentric 'breathing' of the spring, high-precision watches often prefer 'free-sprung' regulation, adjusting rate instead via small weights or screws on the balance rim, avoiding the regulator's inherent positional errors.
Evolution
From simple pinned indexes to micrometric regulators offering finer adjustment (common on higher-grade and railroad-grade watches), and ultimately to free-sprung balances in the most accurate designs, which dispense with a curb-pin regulator altogether.
Known variations
- Simple pinned index regulator
- Micrometric (screw-adjusted) regulator
- Free-sprung balance with no curb-pin regulator
Identification for collectors
- A graduated arc near the balance cock with an adjustable lever or screw is the regulator; its absence suggests a free-sprung balance
Common failure modes
- Curb pins gripping the spring too tightly, distorting its shape and causing erratic rate
- Regulator index slipping from vibration if not securely fixed
Photographs
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Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Daniels, G., Watchmaking
- de Carle, D., Practical Watch Repairing
Where sources disagree, the disagreement is stated rather than resolved silently.