Technology Digests / Analysis of Flange Bearing Frog Crossing Diamond Performance Issues

TD22-023

September 1, 2022
Authors
  • Benjamin Bakkum
  • Duane Otter
  • Stephen Wilk
  • David Davis
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Key Findings

  • With more than a decade of revenue service observation, common flange bearing frog (FBF) crossing diamond degradation modes have been identified.
  • The service lives of flange bearing running surfaces should be improved through some combination of better materials, better lateral distribution of wheel/rail contact, cross-sectional profile of the FB bars, and ramp design.
  • Guard rail wear can be significant for flange bearing crossing diamonds. Consideration of potential installation sites should include proximity to curves.
  • Uneven wear, especially in the longitudinal direction, is occurring on FB surfaces.
  • FBF crossing diamonds are difficult to maintain in track due to the need for running surface continuity at locations where segments of flange bearing bars abut each other. Modularity of replacement components would also be helpful.

Analysis of Flange Bearing Frog Crossing Diamond Performance Issues

Over the past 15 years of safe revenue service operations, the industry has gained valuable experience and insight into flange bearing frog (FBF) design. MxV Rail (formerly TTCI) measurements have shown that FBF crossing diamonds have reduced wheel/rail impact forces and reduced speed restrictions compared to conventional crossing diamonds.1,2 As the industry moves to the next generation of FBF designs, the lessons learned will help improve the safety and economic performance of crossing diamonds in the future. Design challenges and potential solutions include the following. FLANGE BEARING SURFACE WEAR (METAL FLOW AND WEAR) The transition from a tread bearing surface(TB) to flange bearing (FB) surface can be a significant loading event for the crossing diamond. Due to the differences in rolling radius, a wheelset’s rotation speed will decrease when going from TB to FB. While the wheelset’s forward speed does not change, its rotation rate is affected, resulting in high…