The balance and spring assembly represents the heart of the watch; it regulates the flow of time by means of the oscillations of the balance and is responsible for the accuracy of the watch.
The balance performs a circular to-and-fro motion and divided up time into equal units.
- The pallet-lever gives an impulse to the balance to make it perform one rotation: the TICK sound
- During this rotation, the balance-spring is compressed, thereby balancing the energy distributed
Then the balance-spring uncoils and forces the balance to swing back : the TOCK sound
- The to-and-fro principle is achieved, corresponding to an oscillation
A new impulse is then given by the pallet-lever
An oscillation is composed of 2 vibrations.
- A frequency of 2.5 Hertz is equivalent to 18,000 vibrations per hour (meaning 5 vibrations per second)
- A frequency of 3 Hertz is equivalent to 21,600 vibrations per hour
A frequency of 4 Hertz is equivalent to 28,800 vibrations per hour
A frequency of 5 Hertz is equivalent to 36,000 vibrations per hour (meaning 10 vibrations per second)
The energy thus regulated is transmitted to the hands by a set of wheels.