Bearing Failure Causes Train Derailment(pic)

A late July CSX train derailment in rural Greenup county, Kentucky, has been traced to an axle failure caused by a contaminated, overheated bearing and axle box. In the accident, 21 of 73 freight cars carrying 40-ton steel coils derailed, hitting a natural gas pipeline and forcing approximately 50 local residents to evacuate the area. A bridge also had to be shut down until repairs were completed. CSX officials determined an axle journal bearing on one of freight cars overheated, locking up the solid axle on one end as the wheel on the other end tried to continue rotating freely. The weight and power of the forces working on the axle caused it to shear immediately, which in turn allowed the wheels to collapse and derail the train. Although CSX operates infrared "hot box" detectors on this line to spot overheating journal bearings, no warnings were triggered.