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The aspects of real engineering surfaces are discussed with regard to their three-dimensional nature. A review of potential uses of surface finish measurement methods are discussed for characterization of functional surfaces. The use of an optical-based system and measurement procedures are discussed as a means of differentiating surface roughness and its texture of functional surfaces by surface engineering parameters. Using an optical-based system and a set of specific measurement procedures, two functional surfaces with different roughness were analyzed to illustrate a typical surface topography evaluation. A simple sliding test is then utilized to show that a special finish produced by a proprietary finishing process can provide improved performance, as measured by wear differences, frictional properties and operating temperature of the system.

Predicting fatigue performance in concentrated contacts under thin film (or mixed) lubrication conditions has historically involved various empirical approaches. Typically a lubrication parameter is used in an experimentally derived equation to predict the expected rolling contact performance. However, this model doesn't explain the performance improvements. Enhanced finish bearings have exhibited longer life than standard finish bearings, especially when bearings are operated with thin EHL film. In this paper, the contact surfaces of test bearings were analyzed by using a micro-macro contact model in which the macro-contact was elastic contact, and the micro-contact was elastic-plastic contact. The interior subsurface stress maps were calculated from the real contact surfaces, which included the effects of roughnesses, waviness, and profiles.

Lubricant formulations and lubricant additives have been slanted heavily toward protecting gear concentrated contacts from galling and wear. Much of the performance differentiation of these lubricants has been dependent on highly accelerated standardized laboratory testing. The area of contact fatigue has played a less important role in shaping lubricant formulations, but new test results for several commercially available gear lubricants suggest this area warrants a closer examintion. The implications of these findings for equipment applications are discussed, and suggestions are made for ways to minimize or avoid potential detrimental performance effects.

Environmental effects on fatigue and non-fatigue modes of tapered roller bearing damage are discussed. Primary emphasis is placed on the influence of load, speed, lubricant and temperature on the fatigue modes of damage. Effects of dissolved water in oil, traction fluids and fire resistant hydraulic fluids are included.

Increased size, payload and horsepower requirements are the trend in today's off-highway industry. This paper discusses the role of new anti-friction roller bearing technology in avoiding problems created by changing design considerations and the performance/cost/EPA triad currently squeezing designers and manufacturers of rubber tired earthmoving machinery. A comparison is made of bearing fatigue life determined by several methods including those derived from vehicle instrumentation and purely empirical criteria. Some common problems relating to the mounting and set up of large wheel bearings are also reviewed together with corresponding remedies.

Engineering thermoplastics have greatly improved over the last decade. As a result of these improved performance characteristics and their becoming more cost competitive with traditional cage materials, their use in tapered roller bearing cages has become a reality. Design flexibility, lighter weight, resistance to handling damage, etc. make them attractive. This paper does point out certain characteristics of thermoplastics which must be taken into consideration thus influencing the choice of material and what environments they can endure. Compatibility with lubricants at elevated temperatures, growth from moisture and thermal expansion, solvent resistance, impact resistance, strength and dimensional stability are the major considerations. Thermoplastics have found a place in the tapered roller bearing family.

Over the last ten years fatigue tests or wear tests, with and without debris present, have been performed on at least 11 different bearings including five sizes of ball bearings, five sizes of tapered roller bearings and one cylindrical bearing. After evaluating these tests, which include two series that were conducted in the author's laboratory, six factors have been identified that influence bearing performance when debris is present. These factors are debris (size and distribution), lubricant system, lubricant film thickness, levels of filtering, bearing materials and contact size. The results are summarized in table form.

The tapered roller bearings employed in axle centers for the pinion support are critical components in determining the noise, fuel economy and reliability characteristics of the vehicle. They represent a relatively complex mechanical and tribological system, with special requirements from the stiffness, lubrication and heat transfer points of view. This paper brings a contribution to the investigation of the intricate dependency between design parameters, environmental factors and the resultant performance of a package bearing in an integral double cup configuration. Axial compactness, reduced weight, and superior rigidity are only few of the multiple advantages recommending this type of double row bearings for automotive driveline applications. Different aspects related to the tapered roller bearing setting are analyzed in a theoretical and experimental manner, also under the consideration of the manufacturing and assembly processes.