Recent studies have shown that freight car wheels in revenue service may developed tread irregularities in the form of slid-flats, shells and spalls which can cause excessive impact loads. This paper presents the results of a series of tests performed on track and equipment to assess the effects of wheel tread irregularities, such as, flats, spalls, out-of-rounds, and built-up tread. The wheel impact load tests were run at the Transportation Test Center with 70 and 100-ton cars instrumented to measure the roller bearing loads and axle and carbody accelerations over tangent and curves track with instrumented track sections. The test results indicate that the impact loads due to wheel tread defects are transmitted to truck components and car structure after some attenuation. The measured peak bearing adapter accelerations range from 50 to 125 deg, depending on the defect and track construction type. Although considerably attenuated, the high frequency components of the impact loads and accelerations were measured and quantified on the bolster and car body structures. The highest loads and accelerations were measured under the cars with out-of-round and built-up treated type defects. The effect of wheel tread defects at the wheel/rail interface was much more pronounced: rail impact loads as high as 190,000 lbs were measured under the 100-ton car with out-of-round wheel at 40 mph. The test results also showed that a newly maintained track can experience substantial damage due to repeated hammering with wheel tread defects.
Transmission of wheel impact loads into the vehicle and track structures
Übertragung von Stoßbelastungen der Räder auf den Fahrzeugaufbau und die Geleise
1991
13 Seiten, 24 Bilder, 18 Quellen
Aufsatz (Konferenz)
Englisch
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