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DescriptionChain drive, Su Song's book of 1092.jpg	The oldest known illustration of an endless power-transmitting chain drive. This was illustrated in 1092, during the Song Dynasty, by the Chinese engineer Su Song in his book Xinyi Xiangfayao. It was called the "celestial ladder", and was used for coupling the main driving shaft of his clock tower to the armillary sphere gear box (which was mounted at the top of the tower in Kaifeng).
Date	1092 AD
Source	Joseph Needham's Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering (1986, Taipei: Caves Books Ltd.)
Author	Su Song 蘇頌

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File:Chain drive, Su Song's book of 1092.jpg