A slender flat coiled spring regulating the movement of the balance wheel in a watch.
- ‘When the spring is released current ceases to flow in the coil allowing the hairspring to return the balance.’
- ‘In most cases they used a long extension of the hairspring and pinned it to the base of the balance cock.’
- ‘The curb pins on the regulator must be adjusted so that the hairspring hits them when it is supposed to.’
- ‘The two hairsprings are offset at 180 degrees to provide optimal balance, better regulation, easy adjustment, improved stability and greater precision.’
- ‘This oscillation is not exactly a parallel to the balance wheel and hairspring of a clockwork watch, but the fact is that both use oscillations to keep track of passing time.’