Technical Reports

Dynamic Buff and Draft Testing Techniques

  • 01
  • Oct
  • 1992
AUTHOR: Federal Railroad Administration; Magdy El-Sibaie
SUBJECT: Facilities & Test Equipment, Rail and Infrastructure Integrity
KEYWORDS: Draft, Buff, Coupler, Wheels
ABSTRACT: The Federal Railroad Administration and the Association of American Railroads have jointly sponsored a program for developing cost-effective and rational techniques for evaluating the curving performance of any freight car under buff and draft conditions. The procedures arc developed as possible inclusions to AAR Manual of Standards and Recommended Practices, Specification M-l001, Chapter XI. Under this program, an analytical method was developed for predicting coupler angles and forces for any given coupling arrangement and operating conditions. The method was validated in a series of full scale track tests. A test vehicle was also designed and constructed for the purpose of applying controlled levels of lateral coupler loads at the coupler pin of any adjacent candidate car. The test car was used to evaluate the safe curving limits of two candidate cars, namely the Frontrunner and the 89-foot flatcar, under buff and draft loads of up to 250,000 pounds and for a 10-degree curve. The tests, supported by analysis, showed that coupling of the Frontrunner to the 89-foot flatcar reduces the flatcar's ability to negotiate curves safely for draft loads higher than 220,000 pounds and buff loads higher than 180,000 pounds.
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