Somewhat of a mystery are these bronze cogs and other bits and pieces which were discovered in a pit in the mausoleum of Emperor Wen of Han (d. 157 BCE) excavated at Jiangcun (陕西西安江村大墓) in 2021 http://kgzg.cn/a/398176.html
They are roughly contemporaneous with the (vastly more complex) Antikythera mechanism, which gives an idea of what might have been possible, but there seems to be little research on them yet. This article does investigate and discount some theories http://news.youth.cn/jsxw/202112/t20211217_13355873.htm…