Reconstruction Design of Power System and Transmission System of Su Song’s Clock Tower

    Su Song's Clock Tower, invented by Su Song and built by Han Gong-Lianand technical officials in Grand Astrology Administration in 1,086
1,092 AD, during Northern Sung Dynasty, was the first water-powered astronomical clock tower integrating the work systems of armillary sphere (for astronomy observation), celestial globe, and time-keeping system. Based on historical record research of Xin Yi Xiang Fa Yao, written by Su Song, Su Song’s Clock Tower was divided into power system, transmission system, and working system for institutional analyses. Furthermore, the software SolidWorks was utilized for Reconstruction  design and analyses that the power system was completed Reconstruction .


    The power system consisted of two level noria device, waterwheel steelyard-clepsydra device, and waterwheel lever escapement device. The water-powered device was the step water wheel of the astronomical clock tower for generating regular intermittent motion. Made from bronze, the Reconstruction  was produced with traditional crafts and the same size of the original (4.7Lx2.3Wx4.2H). Besides, eight timing units between 14.4
144 secs were applied

to the experiments of accuracy and repetition of step motion. The results proved that Su Song’s Clock Tower presented excellent capabilities of astronomical observation and time telling.


    The transmission system was the institutional system transmitting motion and power from the power system to day and night time-keeping wheel, celestial globe, and armillary sphere. In this study, the gear trained transmission system with shaft was utilized for the Reconstruction  design where one of the better gear sets was selected, from twelve sets, for solid design with SolidWorks. Furthermore, both the observing system and the time-telling system were proceeded analyses of structures and motion as the requirements and theauthentication for the Reconstruction of power system and transmission system.