Zytglogge - Movement

Movement

The clock dial has been dated to either the building phases of 1405 or 1467-83, or to the installation of the Brunner clockwork in 1527-30. Ueli Bellwald notes that the planisphere uses a southern projection, as was characteristic for 15th-century astronomical clocks; all later such clocks use a northern projection. This would seem to confirm the dating of the clock to the 1405 or 1467/83 renovations.

A clock is documented in this tower since 1405, when a new bell was installed. The city accounts of 1438 mention the repair of the clockworks. The first mention of a dial is in 1443, and the first known image of the, much smaller first astrolabium dial (in the diary a cobbler journeyman from Ulm) is dated 1534. The jacquemart (bellstriker) is also documented in the same 1534 source. In the first two decades of the sixteenth century many craftsman unsuccessfully tried to improve the clockworks. The current movement was made in 1530 by clockmaker Kasper Bruner and is dated and signed by a forged nameplate. No other clockworks by this master are known. The core of the movement was forged in-situ, in the very room it is still located, and the fire pit of the forge remains in the room. One of the more unusual features of the movement is that each individual tooth of the major gears is removable (i.e.replaceable as it wears). Originally the movement had a verge escapement with a foliot, as it was built 127 years before the pendulum clock was invented. The Zytglogge movement was converted to a much more accurate pendulum mechanism by the French clockmaker Pierre Angely between 1686 and 1688. The current pendulum bob, a "recycled" iron cannon ball, possibly dates from that time. The pendulum suspension is made from leather rather than using a metal spring. The weight-driven movement is wound daily by hand. That task, a role known as the "Zytgloggenrichter", has been held for over 25 years by the same individual.