Count wheel

Count wheel striking: the unequally spaced notches in the external count wheel on the right side of this tower clock movement regulate the number of times the bell is struck. Two technologies have been devised by clockmaker's to enable striking clocks to correctly count out the hours. The earlier technology is called count wheel striking. This uses a wheel that contains notches on its side, spaced by unequal, increasing arc segments. This count wheel governs the rotation of the striking train. When the striking train is released by the timekeeping train, a lever is lifted from a notch on the count wheel; the uneven notches allow the striking train to move only far enough to sound the correct number of times, after which the lever falls back into thatch and stops the striking train from turning further.