Draft gears and cushioning devices absorb energy during relative motion between two coupled railcars. This may occur in the form of buff and draft forces during over-the-track operation or impact forces during a coupling event in a switching yard. During such events, the end-of-car device absorbs energy that would otherwise be transmitted and possibly cause damage to the car body and/or lading. Health and performance of the end-of-car device is therefore of concern to shippers and car owners. Damaged cushioning units may be identified by visual inspection if the device is leaking hydraulic fluid or by a unit condition indicator, but may not be noticed until damage has been caused to the car and/or lading.

This paper presents the results of a study on the detection of a faulty end-of-car cushioning unit. A boxcar with 15 inch travel cushioning units installed on both ends was deployed for field service. The draft systems were inspected prior to the car being deployed, and although both ends of the car initially showed some signs of wear, there was evidence of heavier wear as well as signs of leaking on the B-end cushioning unit. The goal of the field trial was to determine whether or not the B-end of the car would produce higher magnitude acceleration events than the A-end during revenue service. Three wireless onboard monitoring systems, each with GPS and an accelerometer, were used to determine car location and measure car body accelerations. High car body accelerations were recorded and studied for a three month period of time. The results show that the onboard monitoring systems successfully detected more frequent and higher magnitude acceleration events on the B-end of the car.

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