Fracture fatigue analysis of pump shaft used on locomotive

Aiming at the fracture in operation of damageable pump shaft used on locomotive, macroscopic and microscopic analysis of the pattern of fractured cross section in pump shaft is conducted and it is recognized that the fracture is typically caused by combined action of bending and torsion fatigue. Checking the gear on the pump shaft, it is found that there is excessive processing error with it and a greater additional tensile stress at the root of shaft shoulder is occurred which results eventually in the fracture of shaft. Thus immediate elimination of processing error of the gear as well as improvement installation accuracy will be the key to the prevention of such fracture.