A watch escapement maintains the oscillations of a watch or clock’s balance wheel. It is a mechanical component located within the regulating organ. It works in conjunction with the pallet fork and is essential for the proper functioning of a mechanical movement.

The Composition of the Escapement

This component takes the form of a toothed wheel with the escapement pinion at its center. The shape of the wheel’s teeth differs depending on their engagement with the pallet fork’s pallets. This two-armed pallet fork is mounted on a staff, and the entry and exit pallets (most often made of ruby) adjust relative to the two arms of the pallet fork. The escape wheel rotates clockwise, and thus the teeth of the rotating wheel first encounter the entry pallet and then the exit pallet. At the end of the pallet fork, a small roller is mounted on a larger roller table, which is itself pressed onto the balance staff.

How Does the Escapement Operate?

It is a three-stage movement.

The escape wheel begins by making a slight rotation. After this small movement, the entry pallet of the pallet fork blocks it. Then, at the other end of the pallet fork, at the point of contact with the roller and roller table, the impulse pin engages with the horns of the pallet fork and pivots the pallet fork to release the escape wheel with the assistance of the balance wheel.

This movement ends at the same moment the impulse begins. The pallet and the balance wheel are instrumental in transmitting the rotating escape wheel’s impulse to the pallet fork.

Finally, when the escape wheel is no longer in contact with the entry pallet, the pallet fork comes to rest against the banking pin.

The three phases of this complex movement maintain the oscillations of the balance wheel, which allows a mechanical watch to operate for more than 48 hours without needing to wind the mainspring.