Striking Clock - Passing Strike

The most basic sort of striking clock simply sounds a bell once every hour. This sort of striking clock is called a passing strike clock. It is far simpler to create such a clock; all that must be done is to attach a cam to a shaft that rotates once an hour; the cam raises and then lets fall a hammer that strikes the bell. Originating before the mechanical clock itself, in water clocks, such clocks were the earliest striking clocks; they rang once for each canonical hour, and were used as reminders to summon monks or nuns to their prayers. This sort of striking is still found in some skeleton clocks. It does not require a separate gear train to arm and release the single stroke sounded.

The Tang Dynasty Chinese Buddhist monk and inventor Yi Xing (683–727) created a rotating celestial globe that was given motive power by hydraulics of a turning waterwheel (acting as a large escapement), in the tradition of Zhang Heng (78–139). This featured two wooden gear jacks on its horizon surface with a drum and a bell, the bell being struck automatically every hour and the drum being struck automatically every quarter hour. It is recorded that Confucian students in the year 730 were required to write an essay on this device in order to pass the Imperial examinations. The use of clock jacks to sound the hours were used in later clock towers of Song Dynasty China, such as those designed by Zhang Sixun and Su Song in the 10th and 11th centuries, respectively.

A striking clock outside of China was the clock tower near the Umayyad Mosque in Damascus, Syria, which struck once every hour. It was constructed by the Arab engineer al-Kaysarani in 1154. The Florentine writer Dante Alighieri made a reference to the gear works of striking clocks in 1319. The most famous original striking clock tower still standing is possibly the one in St Mark's Clocktower in St Mark's Square, Venice. The St Mark's Clock was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from Reggio Emilia, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell (h. 1,56 m., diameter m. 1,27), which was put on the top of the tower where it's alternatively beaten by the Due Mori (Two Moors), two bronze statues (h. 2,60) handling a hammer.