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Figure 1: Flow diagram of bearing setout, root-cause failure classification and information reporting. |
Data collected from these setouts is intended to be used for identifying dominant root-cause failure modes and driving changes in the industry. During the mid 1980’s, bearing setouts were predominantly loose bearing failures driven by poor stack clamp conditions. Changes to AAR rules regarding seal car screw o-rings, mounting torque levels, and fitted applications in combination with manufacturer changes to bore tolerances, end cap designs, and cap screw conditions helped to drive the percentage of loose bearing failures from higher than 40% of all hot box setouts in 1988 to less than 25% in 2002. The improvement from less loose bearing setouts can be noted in the reduction of hot bearing setouts per billion net ton miles which has decreased by more than half from 1992 to 2001[2]. Many other bearing design and industry changes have been pursued due to justification provided by close evaluation of bearing setout statistics with similar positive outcomes.
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Figure 2: Industry Verified Setouts from 1993 to 2003 by Identified FPM. Non-verified Setout rate for 11 year span was 30%. Data represents all manufacturers and reconditioners. |
The importance and value of this setout data prompted the railroads and members of the RBMEC to verify the repeatability and accuracy of the information that was being supplied. The current system, which classifies a setout bearing into one of 522 possible categories[3], was found to yield less than 50% agreement among multiple inspectors and even less when comparing multiple inspectors from different manufacturers. It was also identified as limited by its inability to classify bearings from acoustical detectors (or any detector not using heat as the indicator) and its inability to categorize non-verified setouts. The complexity of the setout data drove each manufacturer to derive its own classification system for failures and to report their manufacturer specific code to the railroad in addition to the required MD-11 codes.
The FPM system, devised with the help of the railroads and refined by the RBMEX, classifies failures into one of 13 categories. Multiple validations of this system yielded better than 90% agreement when comparing multiple inspectors and near that when comparing multiple inspectors from different manufacturers. It is designed for use with all detection methods (acoustic, hot box, warm, etc.) and one of its 13 possible classifications specifically determines if setouts are non-verified. As the RBMEC unanimously approved the FPM system, all manufacturers are now employing this improved method for classifying and reporting their setout data to produce a more consistent format.
FPM Categories and Codes
| Code |
Description
|
| AD |
Adapter – Displaced, Worn, Wrong Size or Broken |
| AP |
Application Defects |
| BD |
Bearing Destroyed, Undetermined |
| DS |
Displaced Seal |
| LO |
Loose Bearing |
| LU |
Lubrication |
| ME |
Mechanical |
| MD |
Manufacturer / Remanufacturer / Reconditioner Defect |
| NV |
Non-Verified Setout |
| SP |
Fatigue Spalling |
| TR |
Truck Related |
| WD |
Wheel Defect |
| WE |
Water Etch |
FPM is more consistent, more versatile, and more useful than the current setout bearing classification system. It allows for the railroads and car owners to combine bearing performance data from multiple manufacturers and multiple detection systems to yield an accurate evaluation of bearing performance on their equipment. By classifying and reporting setouts with the FPM, the RBMEC is helping to ensure the integrity of the information that will be used to identify dominant performance issues and measure the effectiveness of changes (in regulations and products) made to address them.
Copies of, or answers to questions about, the Failure Progression Modes can be obtained from your Amsted Rail Group Sales and Service representatives.
The Technical Forum is an information resource for the rail industry and is provided as a courtesy of Amsted Rail Group. Suggestions, inquiries or comments are welcomed and should be directed to:
Editor, Technical Forum
BRENCO, Incorporated
P.O. Box 389
Petersburg, Virginia 23804
804-863-1713
Additional copies provided upon request.
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