Balance spring
Balance spring
(or hairspring)

A balance spring is a fine spiral or helical spring used in mechanical watches, marine chronometers, and other timekeeping mechanisms to control the rate of vibration of the balance wheel. A balance spring usually has a regulator lever to adjust the rate of the timepiece.
Types of balance springs
flat spiral
Breguet overcoil (Breguet spring)
chronometer helix
showing curving ends
early balance springs
TERMINOLOGIE NUMEROTATION
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