This is an auto-rewind mechanism that keeps the clock wound as long as there’s 12-volt power. See All 26 Photos 09.Here’s the time adjustment shaft and gear cluster. The shaft is spring loaded ...

[shiura]’s Hollow Clock 3 is a fantastic 3D printed take on a clock movement that uses a hidden mechanism to pull off ... to hang in the air. Hidden shaft and gearing. This is how it works ...