Technical Reports

Measurement of Wheel Load Environment of AAR M-976 Approved Truck

  • 29
  • Sep
  • 2017
AUTHOR: Federal Railroad Administration
SUBJECT: Rolling Stock
KEYWORDS: Rolling contact fatigue, wheel shelling, shakedown
ABSTRACT: Measurement of Wheel Load Environment of AAR M-976 Approved Truck study (FRA Task Order 319) is the continuation of the Measurement of Wheel Load Environment of a 3-piece Truck study (Task Order 245) completed in November 2010 that increased understanding of the conditions under which wheel rolling contact fatigue (RCF) damage accumulates. In this study the AAR M-976 approved truck had better steering truck performance, in terms of developing less RCF, than the 3-piece truck used in the previous study. Wheel load environment data was collected from a car operating in revenue service and analyzed using shakedown theory to assess the wheel RCF damage. No track inspection was conducted and the study did not include parameters such as track conditions, rail age, and wheel-rail interface friction management applications. Statistical results from the study showed that a 3-piece truck had approximately four times higher probability of developing RCF than an AAR M-976 truck at 5-degree or tighter curves. For both trucks, RCF was predicted at sharp curves and underbalance speed (cant deficiency), such as yard entrance and exit curves, as well as mine and power plant turnaround loops. Recommendations for reducing wheel and rail RCF damage include controlling the wheel-rail coefficient of friction where track curvature is 4 degrees or tighter.