Certain contaminants on the wheels of railroad cars may reduce the effective coefficient of friction between the car wheels and the shoes of the retarders used in classification yards, The result is a reduced capacity of the retarder to decelerate the car. In the extreme case, the car would have minimum deceleration resulting in an excessive overspeed impact with other cars on a storage track. Such a case resulted in the recent explosion and fire at Southern Pacific's Houston classification yard, which was caused by an extreme overspeed impact of a car with an epoxy coating on its wheels. The retarder was unable to furnish proper retardation, even in maximum retard position due to this wheel condition. A proposed control procedure is to install a "slippery wheel detector" before the crest of the classification yard. This device would detect wheels with low friction and alert the yard crew and the automatic control system in the case of an automated yard. Any cars with slippery wheels would not be uncoupled at the crest, but would be handled under an exception procedure under the control of a locomotive. This report describes the first phase of the development of such a detector.
This note documents a simple sensitivity analysis showing system response, as measured by distance headway, as a function of rolling resistance. Inclu...
The basic building blocks of a conventional retarder control system are described from a generic-functional viewpoint. The central function of a retar...
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United States Department of Transportation
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