CSX Transportation has purchased, installed and integrated eight Optical Geometry Detector sites. These detectors measure the wheelset’s angle of attack and lateral position with respect to the tangent track upon which they pass. The objective of this project was to determine the source of extreme geometry measurements. CSX performed 19 teardowns of cars that were identified by the optical geometry system. Many other cars with geometry exceptions have also had close inspections at the repair tracks. This report will summarize how the defects found relate to the geometry exception. CSX has primarily looked at trucks with progressive and repeatable tracking problems, which cover 87% of the geometry exceptions. Key truck measurements recorded include: circumferential wheel tape size, digital wheel profiles, side bearing set up height, center bowl dimensions, side frame length and the distance between the thrust lugs. Many of the geometry exceptions seem to have been caused by mismatched (or asymmetrical worn) wheels. Differences in the circumference force the axle to shift laterally and allow the wheel to continually flange on the gauge side of the rail.

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