DOC-铁道机车车辆相关英语翻译-其他专业.docVIP

Cut wheel fracture problems and maintenance costs Jorg 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 common used wheel type was the so-called 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 half-elliptical or fourth-elliptical 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 committee responsible for the work was the B 169 specialists committee. Three major prob