1) Because of its unique working feature for bearing mechanical impacting for a long time, the main shaft generates fatigue damage.
2) Feed more materials to cause overload operation.
3) There are some wasted metal mixed in the ore during excavation and transportation. When these materials pass through the electromagnet, because of the weak absorption ability of electromagnet and the special metal characteristic of materials which contained manganese steel, they are hard to be removed, so these materials mixed with ore and mud entering into crusher to cause frequently impact on main shaft. In this way, the main shaft generates fatigue damage, this is the main reason to cause breaking.