According to the 102th carriage crown costume in the literature of the history of the Song dynasty, functions of a Yansu south pointing chariot are recovered; the important role of amplifying the rotation angle of a shaft through two small wheels is analyzed, so that the engaging and disengaging speed is increased by one time; simultaneously, a delay principle that wheels at the other side are locked in a non-forced manner is designed; working condition conversion in the event of not having south pointing tasks is completed by using simple accessories; the event proves that design of the Yansu south pointing chariot is successful; the reason that the Yansu south pointing chariot is not analyzed by later generations is as follows: the technical specification and the modern technical specification are different; and the spread information is too simple; analysis thinks that generation of random error is possible, but can be offset with each other, so that the error is small; the Yansu south pointing chariot is capable of realizing the accurate orientating function, so that the event proves that the clutch type south pointing chariot is an feasible historical invention; and in addition, because of having different engaging and disengaging manners, the Yansu south pointing chariot and the Wuderen south pointing chariot are different.