For a relatively short conveyor belt, because of the unilateral roller rotation is not flexible and some other factors are relatively large. Conveyor belt deviation is more likely to occur, and the length of the conveyor belt, due to the increase in the number of rollers, unilateral effects of asymmetry will be reduced. Therefore, the performance of the conveyor belt will be less prone to deviation. Of course, except for individual circumstances. Such as: the center roller is not flexible or fixed tilt, roller surface is not clean, or external environment, etc., can cause the conveyor belt deviation.