A coal mining company in USA transported coal from a mine on a conveyor belt with a width of 64 inches (1600 mm) at a speed of 1.6m/s. During the operation of the belt, the belt was impacted and local coal accumulation was uneven, causing the belt to run on one side. Unfortunately, because the company's conveyor belt had been deviating for a long time and was scratched by hard objects, it finally tore, so it had to stop working.