Breguet Overcoil

The Breguet Overcoil, sometimes known as the Breguet Spiral is a form of hair spring. It differs from the more conventional springs by being bent sharply upwards and back over itself so that it can be anchored near its centre. It is a type of spring used extensively by Rolex and is intended to give greater accuracy and time consistency by reducing the variation in amplitude of the balance wheels swing as tension in the spring ebbs from its fully wound state. It also reduces the wear on the balance pivots.

Bottom PlateBridge