Excessive rolling force and rolling moment are the main reasons for the fracture of the root of the working roller neck and the twisting of the roller diameter bearing force.The fracture of the root of the roller neck may also be caused by the small radius of the circular Angle when the roller root is processed, resulting in the stress concentration or the excessive temperature of the bearing.When the neck of the roller is twisted and the mouth is broken, it is completely because the torque transferred exceeds the design negative load of the working roller neck.The cause of the fracture from the neck of the two working rollers at the same time is that the rollers bear the overload impact force.