For a purely mechanical option, couldn't you use something similar to the level-winders on overhead and baitcasting fishing reels? I couldn't find a decent image to show you how it works. But the shaft is cut like this:
I'm sure you could use some adjustable (and removable) stops on the shaft to set the end-points for when the hooks need to change direction. And also add/remove them depending how many drums you're filling.