A South Pointing Chariot is a vehicle carrying an indicator that always points South. As usual, there’s a good article on Wikipedia.
While the device was mentioned in a number of ancient Chinese texts, no design or construction details have survived. My model (like many others) assumes that a differential gear train was employed.
It’s been a fun project, but it’s a bit too difficult to assemble, and the wheels need work. watch this space for an updated version, including full CAD source files.