Working at Daimler Chrysler one of he regularly scheduled duties was to climb up the ladders going to the overhead conveyors and check and report the status of the conveyor chain slack. The conveyor chain is what drives the car bodies using gear boxes at various locations. Over time The chain streches as air cylinders hold back pressure on the chain. If the chain streches too far it will make a limit switch shutting down the conveyor. Normally millwrights will remove a few links of chain as necessary to keep the limits from making contact. If it happens during production they can just move the limit switch further away temporarily. I remember a time when the electricians would hit the start buttons 30 times and could not figure out why the conveyor would not start. It happened every 2 to 3 weeks and several locations were in constant upkeep.