The static strength of output ring gear for driving bucket-wheel reducer is calculated by ANSYS finite element analysis software after loading analysis.It has enough strength
but has fracture trend to outside of ring gear in according to the result.All possible kinds of reasons which can result in ring fracture are analyzed.Based on analysis results the key reason of ring gear fracture is attribute to the material defection by ultrasonic inspection.The calculating result of finite element supports this failure reason analysis.