A systematic approach to the reconstruction of ancient Chinese escapement regulators

It is generally believed that the first escapement regulator invented is the waterwheel steelyard-clepsydra device made in ancient China by Su Song during the Northern Song Dynasty (960∼1,127 AD). The device, which was a unique feature of the ancient Chinese escapement regulators, was used in Su's famous clock tower, Shui Yun Yi Xiang Tai (Water-Powered Armillary Sphere and Celestial Globe). Evidence found in certain historical literature, however, suggests that the astronomical clocks made before the Northern Song Dynasty were also equipped with escapement regulators. But due to insufficient literature on the specific design of the devices and the fact that none of the earlier escapement regulators have been recovered, it has been very difficult to recreate the original mechanism design. Therefore, in view of this problem, we wish to present a reconstruction design procedure for the ancient machinery in this paper. By combining the innovative mechanism design methodology with the mechanical evolution and variation theory, we can systematically recreate all feasible and appropriate designs that are consistent with the science theories and techniques of the subject time period. In this paper, the waterwheel steelyard-clepsydra device made by Su Song was adopted as the original design for the reconstruction of ancient Chinese escapement regulators. Utilizing the procedure proposed in this paper, the reconstruction designs we recreated included 12 six-bar and eight-joint waterwheel steelyard-clepsydra devices, among which 10 were with four-bar linkages and 2 were with rope-and-pulley mechanisms. These results can be further used in the study of ancient Chinese mechanical clocks, especially in reconstruction research.