Abstract: Ball deformation and inner and outer raceway wear were found on the rolling bearing of primary input shaft of the melt pump reducer of extrusion granulation production line in a polyolefin plant at SINOPEC Guangzhou Company. This paper analyzes the structure of melt pump reducer, calculates and checks the design service life of the two-stage bearing of primary input shaft, and analyzes the causes of the early failure of bearing from the aspects of bearing installation, lubrication and material. It is concluded that the failure is caused by the material defect of rolling element. By replacing the bearing and increasing the amount of oil injection, the reducer and the bearing have been running well since January 2013, and such failure has not occurred again

Key words: extruding granulator, melt pump reducer, bearing, failure