Technical Reports

Broken Rims in Railroad Wheels

  • 31
  • Dec
  • 2014
AUTHOR: Federal Railroad Administration
KEYWORDS: Railroad; Wheel; Crack; Rim; Broken; Broken Rims in Railroad Wheels
ABSTRACT: Broken wheels are one of the most common types of equipment-caused train accidents. The failure of rail car wheel rims, which are usually the result of shattered rims or vertical split rims (VSR), are the leading cause of wheel-related accidents, and they are increasing as a percentage of all equipment-related accidents. The root causes of shattered rims have been agreed upon in the literature and effective mitigation procedures have already been implemented. Inspection, analysis, and testing of microcleanliness and residual stresses have increased confidence in a theory about the root cause of vertical split rim (VSR) failures in railroad wheels. However, two attempts to replicate the VSR failure mode under controlled conditions in the laboratory were unsuccessful, indicating that more research is needed to better understand VSRs and to assess the best potential mitigation methods. VSRs are thought to be the result of tread damage on the wheel surface in the form of a shell or spall that initiates cracking in the rim and produces impact loads when it comes in contact with the rail. If the crack propagates vertically to an area of tensile residual stress in the wheel rim, further crack growth is encouraged until a portion of the rim breaks free from the wheel.