The main function of rolling bearings is to support load and transmit rotational movement with minimum energy loss. In order to achieve this, bearings are manufactured with particularly good quality fatigue resistance materials, proper design and tight manufacturing tolerances. Particular emphasis is put in both the macro, and micro geometry of the working shapes and surfaces of the raceways. Rolling bearings come in many types and sizes as ball and roller bearings for radial and thrust loads.

Until now the estimation of rolling bearing life has been based on engineering models that consider an equivalent stress, originated beneath the contact surface, that is applied to the stressed volume of the rolling contact. Through the years, fatigue surface–originated failures, resulting from reduced lubrication or contamination, have been incorporated into the estimation of the bearing life by applying a penalty to the overall equivalent stress of the rolling contact. Due to this simplification, the accounting of some specific failure modes originated directly at the surface of the rolling contact can be challenging. In the present article, this issue is addressed by developing a general approach for rolling contact life in which the surfaceoriginated damage is explicitly formulated into the basic fatigue equations of the rolling contact. This is achieved by introducing a function to describe surface-originated failures and coupling it with the traditional, subsurface-originated fatigue risk of the rolling contact. The article presents the fundamental theory of the new model and its general behavior. The ability of the present general method to provide an account for the surface–subsurface competing fatigue mechanisms taking place in rolling bearings is discussed with reference to endurance testing data.

Engineers typically learn that the bearing L10 life can be estimated using the so called “C/P method” — or the “basic rating life” of the bearing, a method rooted in the 1940s. Major developments have since led to the “modified rating life,” released in ISO 281:2007, which includes the aiso life modification factor. In this paper a succession of equations used for bearing life ratings are reviewed, and current bearing life rating practices are discussed in detail. It is shown that — despite the introduction more than 30 years ago of the adjustment factor of the basic rating life, and the standardization in 2007 of the aiso modification factor — use of these improved calculation methods are not practiced by all engineers. Indeed — many continue referring to the old model as a way of seeking compliance with existing, established practices.

This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.

Passenger transport today moves significantly faster than ever before, often operating on separate tracks especially designed for high-speed trains. Accordingly, high-speed rolling bearings are very important components in the bogies of trains today. Maximum train speeds currently reach 380 km/h (236 mph) in the latest high-speed applications - 80% higher than in the earlier days of high-speed traffic. This paper presents two application examples of modern, high-speed traffic, together with some typical bearing arrangements and housings. It provides insight regarding measures taken in the bearing industry to meet the requirements of contemporary, high-speed traffic, and it cites important standards and regulations applicable for - but not restricted to - European applications. To be precise, the focus here is on journal bearings; information on traction motor bearings, transmission bearings and housings is included, but described in less detail.