Technology Digests / Effect of Higher Flow on Brake Cylinder Pressure

TD24-002

June 26, 2024
Authors
  • Yi Wang
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Key Findings

  • A brake pipe flow limit of 60 scfm at a single air source indicates the train’s ability to produce adequate brake cylinder pressures.
  • Trains with more locomotive consists consistently produced higher brake cylinder pressures under similar leakage conditions.
  • Subject to further physical validations, there is potential for the total allowable leakage to increase based on the number of air sources and the BP length between them.

Effect of Higher Flow on Brake Cylinder Pressure

Under the Association of American Railroads’ (AAR) Strategic Research Initiatives (SRI) program, MxV Rail performed a simulation study to understand better the effect of higher brake pipe (BP) flow on the brake cylinder pressure. This study was made possible using a new TOES™ feature that models concentrated BP leakages from a subset of cars on a train. BACKGROUND The test for brake pipe leakage is an integral part of the Class 1 and No. 1 brake tests in the United States (U.S.) and Canada.1,2 The test can be conducted using either the traditional leakage test or the newer air flow method (AFM) test. Currently, the AFM test requires the train to have no fewer than 75 psi at the lowest point of the BP. For trains with a single locomotive consist, the maximum BP flow is not to exceed 60 scfm; for trains with two or more locomotive consists, the…