Self-aligning Principle: The idlers on both sides are conical. When the conveyor belt is running, there is sliding between the side idlers and the conveyor belt, and the sliding friction force between the side idlers and the conveyor belt is consistent with the running direction of the conveyor belt. When the conveyor belt runs in the middle, the sliding friction forces on both sides are the same; when the conveyor belt deviates, the sliding friction on the deviated side increases, pushing the conveyor belt back to the middle position.