If you go look at the back of the thing, there is a line going back to the beginning. So when you send a pulse down the line, then it will creating a looping signal. It's not exactly a clock in the normal sense, but the whole mechanism is a big clock. like you can track the path of the redstone repeaters to see that it's a loop. I mean maybe there is something wrong with this save file. Let me go check on that :)