鐵道機(jī)車車輛相關(guān)英語(yǔ)翻譯-其他專業(yè)-文庫(kù)吧資料
2025-01-27 01:26本頁(yè)面
【正文】 nmachined web. In addition to the calculation fatigue tests can be required. This depends on the results of the calculation and on the validity of the conventional loads. Two methods for fatigue tests are possible, either a random fatigue test or a onestage fatigue test8. For both methods the test loads are derived from measured loads during field tests. Concerning the acoustical aspect it is, of course, not a target that new developed wheels have higher sound radiation pared with existing designs. Therefore a sound level is described which is parable with the former ORE standard wheels8. The sound level can be determined by a calculation. The acoustical requirements are informative only. Product development and verification The stress ranges for the various designs are calculated as follows: * Wheel (BA 004)/ (BA 304) 177。Cut wheel fracture problems and maintenance costs J Villmann looks at the problems of wheel fracture and the development of new designs to reduce failure problems and maintenance costs. In the late 1960s and 1970s axel loads and speeds of railway vehicles increased rapidly. This led to higher thermal an mechanical loads of the wheels. Tiered wheels showed loose types after strong heating during runs on mountainous lines or following to brake irregularities. Maintenance costs for type changing increased more and more. In order to solve these problems solid wheels were introduced. The most mon used wheel type was the socalled ORE wheel developed by the European railways under the roof of the ORE (today European Rail Research Institute ERRI) as the research institute of the UIC (International Union of Railways). Following the extended use of solid wheels in connection with a block brake, the unforeseen problem of wheel fracture occurred. Investigation of failured wheels showed that two principal forms of wheel fracture occurred radial fracture from the wheel rim straight through the web down to the hub or beginning in the rim, running straight in to the web and shared in two branches. It was also found that the fracture was initiated from halfelliptical or fourthelliptical fatigue cracks, which started on the tread, around the chamfer or due to sharp notches from clamping devices of reprofiling lathes. Detailed investigation showed that all failured wheels were thermally damaged and had high residual tensile stresses in the rim of about 300 MPa. Though the number of failed wheels was relatively small each failure could lead to devastating consequences. Therefore intensive research work was carriued out to improve this situation. Research programme The European Rail Research Institute (ERRI), which is part of the UIC, was selected to lead the project work. The mittee responsible for the work was the B 169 specialists mittee. Three
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