Hmm. There are several parts of the game that are like that. There are multiple conveyor belts or different sizes throughout Timeshift...
Well, the solution for one of the puzzles is standing on the belt and reversing time (you'll be taken with the belt back through the area where the belt comes from, thus allowing you to move on).
I'm pretty sure there's another place where you need to get off of a conveyor belt and go find a button to get it started.
However, I can't help you with specifics unless you describe the exact place where you're stuck.