What is the Mainspring in an automatic Watch movement?

The mainspring is a key component of an automatic watch movement. It is a coiled spring that stores energy and powers the watch as it unwinds. The mainspring is wound by the movement of the rotor, which is a weight that is attached to the movement and rotates as the wearer moves their wrist.

As the rotor turns, it winds the mainspring, which stores energy in the coiled spring. The mainspring is connected to the gear train of the watch, which consists of a series of gears that transfer energy from the mainspring to the hands of the watch. The gear train consists of the center wheel, third wheel, fourth wheel, and escape wheel.

The center wheel is driven by the mainspring and turns the third wheel, which in turn drives the fourth wheel. The fourth wheel drives the escape wheel, which is part of the escapement mechanism. The escapement is a mechanism that controls the release of energy from the mainspring to the balance wheel, which is a small, oscillating wheel that is responsible for keeping the watch running accurately.

As the escape wheel turns, it pushes the pallet fork, which is a lever that engages with the teeth of the escape wheel. This releases a small amount of energy to the balance wheel, which oscillates back and forth at a consistent rate. The balance wheel is mounted on a balance staff, which is a finely polished and tapered pivot that allows it to rotate.

The movement of the balance wheel is controlled by the balance spring, which is a spiral spring that returns the balance wheel to its central position after it has oscillated. The balance spring is attached to the balance staff at one end and to a stud at the other end. As the balance wheel oscillates, the balance spring expands and contracts, which controls the movement of the balance wheel.

The mainspring, rotor, gear train, escapement, balance wheel, and balance spring all work together to keep the watch running accurately and efficiently. The mainspring stores energy and powers the watch, the rotor winds the mainspring, the gear train transfers energy from the mainspring to the hands of the watch, the escapement controls the release of energy to the balance wheel, and the balance wheel and balance spring keep the watch running accurately.