An external load applied to a radial rolling bearing is distributed among the rolling elements. In many applications, the bearing internal load distribution may be altered by the elastic deformations of the bearing rings. This alteration can have an effect on bearing life. The objective of this study is to investigate the effect of load distribution on bearing life, both theoretically and experimentally, using several housing models which provide different contact conditions between the housing bore and the outer ring. This paper first presents a newly developed method of determining dynamic load distributions with an optical fiber strain sensor. The measurements of the load distribution for the housing models by using this method have shown that the contact condition between the housing bore and the outer ring affects the load distribution, and the effect of the load distribution on the bearing life has been confirmed by the theoretical calculation of the bearing life. Furthermore, endurance tests using dented bearings were performed to validate the effect of load distribution on bearing life. The results of the tests have substantiated that the bearing life is substantially affected by the load distribution; moreover, it has been shown that there is a linear relationship between the calculated lives and the experimental ones.

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The fretting wear is caused by the very slight relative slip between the contacting surfaces of the inner ring side face and the backing ring of an axle journal bearing in railway applications, but its mechanism is not clear. In this work, first we have conducted a reproduction test using a full-scale railway axle journal bearing in order to understand the fretting wear behavior of the axle journal bearings. Secondly, laboratory tests using a full-scale railway axle journal bearing were conducted to investigate the contact pressure distributions by inserting a film pressure sensor between the inner ring side face and the backing ring of the axle journal bearing under the conditions of radial loads. It has been found that the fretting wear of the backing ring becomes larger in the proximity to its outside diameter, the contact pressure of the opposite of the load side is larger than that of the load side and the contact pressure becomes larger in the proximity to its outside diameter. Accordingly, the fretting wear area of the backing ring is approximately coincident with the area where the amplitude of the contact pressure is large.

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Recently, environmental protection has become one of the most critical concerns in the global scale. Currently, it is widely recognized that life cycle assessment (LCA) is a very effective instrument to quantitatively evaluate environmental impact of various products across their whole lifecycle. LCA itself is not yet established as a well defined method, but already finding a wide range of applications in electric appliances, automobiles and other industrial products. We conducted a basic survey for LCA of Shinkansen vehicles, as a case study for the railway system. As a result of this survey, we could obtain useful knowledge for applying LCA to the railway.