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Several papers have already been published on the subject of failure analysis of rolling bearings. These papers are very useful. However, with the advancement of bearing technology bearings are increasingly being used in more severe applications. As a result, bearings are experiencing types of failures not described in previous publications. This paper focuses on the quick diagnosis of failed rolling bearings using a magnifying glass or microscopy of low magnification with the emphasis on those failures which have not been previously described.

Rolling contact fatigue lives of various steels used for medium- and large-sized bearings were investigated, using Φ60×ι90 specimen. Through hardened steels and induction hardened steels have nearly the same life, while carburized steels have lives about 3 times as long as that of through hardened steels. Since rolling contact fatigue life is affected by the cleanliness most significantly, it is most important to use clean steels for good bearing life. The influence of chemical compositions upon rolling contact fatigue life varied with cooling speed during quenching of the specimen. Using a steel which has excessively high hardenability for a small-sized bearing leads to a poor rolling contact fatigue life. For a medium or large-sized bearing we have to use a steel which has high hardenability necessary for the thickness of the bearing, but it seems unnecessary to pay close attention to the steel type.

This paper presents a method of measuring rolling element loads within large size ball bearings of four-point contact configuration. The rolling element loads are measured with an original method under five fastened conditions for a turntable bearing. The rolling element load distribution is obtained, and the results are compared to the computed loads and distributions.

While rolling contact fatigue life of steels has been much improved by the improvement of cleanliness in steels due to progress in steel-making techniques, the demand for longer bearing fatigue life is ever-increasing. It will be necessary to find the best chemical composition and the best heat treatment conditions to further increase bearing fatigue life-Since bearing fatigue life also depends on the running conditions under which the bearing is used, it is also necessary to use material which meets the running conditions best. Carburizing steels generally have longer rolling contact fatigue life than through hardening steels. However, under debris contaminated lubrication such as in automobile transmissions, there were some cases where carburized bearings did not show such longer fatigue life.

Progress in the steel making process has improved the rolling contact fatigue life of bearing steels. Based on identical tests, conducted periodically over the past 20 years, improvements in the rolling contact fatigue life of through hardening bearing steels and various carburizing steels are described. Improvements in steel quality may alter the influence of various factors on rolling contact fatigue life, and because of this it is necessary for them to be re-examined. Based on recent test data, the influence of factors such as oxygen content, alloying elements, fibre orientation, steel making procedure and heat treatment factors such as microstructure and cooling speed during quenching on rolling contact fatigue life are described.