Mechanism for a bell tower clock with verge escapement and foliot
In the wrought iron castle, with the external uprights ending in spiral decorations, there are two trains of gears, for the ringtone and for the time. The two trains were driven by the lowering of two different weights, connected to ropes wound around horizontal cylindrical drums. The speed of the ringtone train (with three gears) is regulated by a fan. Air resistance slows down the rotation of the fan which, after an initial acceleration, reaches a constant number of revolutions and ensures that the chimes of the hours follow one another at regular intervals. The time train (with two gears), on the other hand, is equipped with a much more refined regulator, called verge escapement with foliot. Known since the 14th century, the verge escapement is made up of a vertical shaft with two blades that engage on a toothed crown with a horizontal axis. The release of the driving force provided by the weight occurs at intervals regulated by the alternating release and blocking of the blades and sawtooth of the crown. The foliot is inserted into the upper part of the verge. The two sliding weights allow for the changing of the period of oscillation of the balance in order to fine tune the speed of the time train.