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Technical Paper

Timken: From Missouri to Mars – The History of the Future

1999-03-02
1999-01-1318
The 100-year saga of The Timken Company is a testament to the enduring power of innovation, grit and periodic self-renewal. It is the story of a quest to solve one of industry's oldest, most limiting and expensive challenges: friction. Today's Timken combines materials science with bearing technology to produce products that range from a half ounce to nine tons and help power and control applications that span disk drives, drilling rigs, dental drills and rolling mills. Today's automotive bearing is less than half the size and 90 percent lighter than its ancestor - and carries twice the load.
Technical Paper

The Impact of Some Gear Lubricants on the Surface Durability of Rolling Element Bearings

2006-04-03
2006-01-0357
The additive chemistry of some gear lubricants can have a major impact on the surface durability of rolling element bearings (1). Lubricant formulation has been slanted heavily toward protecting gear concentrated contacts from galling and wear. As such, much of the performance differentiation of lubricants has been dependent on highly accelerated, standardized laboratory tests related to gears. Methods have been proposed to evaluate and quantify a lubricant's performance characteristics as they relate to rolling element bearings (2). Results from several lubricant performance evaluations are presented. The implications of these findings suggest that the detrimental performance effects on rolling element bearings need further fundamental study by the lubricant industry.
Technical Paper

Repair as an Option to Extend Bearing Life and Performance

2007-10-30
2007-01-4234
Repair and remanufacture has become an accepted method to extend bearing useful life in many applications, including positions within off-highway construction and mining vehicles. However, it has not been an easy task for equipment owners to become confident in the use of repaired bearings, nor has it been an easy task for engineers to select the positions best suited for repair, as robust analytical methods to predict performance are not available. This has lead to many field test campaigns of repaired bearings on different bearing positions until the equipment owners gain enough confidence to make it part of their normal operating procedures. This paper aims to reduce the test and validation cycle that occurs with the use of repaired and remanufactured bearings by developing analytical methods to predict bearing performance. Life prediction algorithms are presented covering the different levels of repair available.
Technical Paper

Performance Evaluation of a Potential New Engineered Surface for Enhanced Concentrated Tribological Contacts

1998-04-08
981475
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 is discussed for characterization of functional surfaces. 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 was 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. A special surface treatment was then evaluated in conjunction with the special finish in order to enhance its functional load support. Simple sliding test results indicates a potential new engineered surface for improving tribological contact performance.
Technical Paper

Near Net Shape Seamless Tubing for Automotive Parts

1990-02-01
900297
A method of manufacturing has been developed to produce externally profiled mechanical seamless tubing for cams, races and similarly shaped parts, rather than machining these profiles from tube blanks or forging them to net-shape from powder metal. The desired profile is produced on the outside diameter of the entire length of a tube by cold drawing. Discrete parts cut from these tubes will have the surface finish, mechanical properties, and dimensional accuracy typical of cold formed products. In addition, relative to the use of tube blanks, material yield is increased since OD machining is eliminated.
Technical Paper

Methods for Assessing the Bearing Surface Durability Performance of Lubricant Formulations

2005-10-24
2005-01-3808
Lubricant formulations and lubricant additives have been demonstrated to have a major impact on the surface durability of rolling element bearings. However, there are very few standard tests used to assess the performance aspects of lubricants as they relate to bearing surface performance. Lubricant formulations have been slanted heavily toward protecting gear concentrated contacts from galling and wear. In addition, much of the performance differentiation of lubricants has been dependent on highly accelerated, standardized laboratory tests related to gears. Methods have been developed for properly evaluating a lubricant's performance characteristics as they relate to bearings. These methods are explained and the corresponding test results are reviewed, to show their effectiveness as lubricant performance evaluation tools.
Technical Paper

Improving the Performance of Rolling Element Bearings with Nanocomposite Tribological Coatings

2006-10-31
2006-01-3555
This study summarizes the development, characterization, and application of nanocomposite tribological coatings on rolling element bearings. Nanocomposite coatings consisting of nanocrystalline metal carbides embedded in amorphous hydrocarbon or carbon matrices (MC/aC:H or MC/aC) have been used to increase the fatigue life under boundary layer lubrication, provide debris tolerance, eliminate false brinelling, increase the operational speed, decrease the friction, and provide oil-out protection to rolling element bearings. MC/aC:H coatings are applied by magnetron sputtering at substrate temperature less than 180 °C, have small friction coefficients, high fracture strength, and can have hardness and modulus values twice and half that of carburized steel, respectively.
Technical Paper

Highly Compact Electric Drive for Automotive Applications

2004-10-25
2004-01-3037
The penetration of hybrid or purely electric drivetrain solutions in automotive applications increases continuously, benefiting also from the rapid advancements in the complementary technologies related to the on-board electric energy generation and storage. The automotive community has made a strong commitment to the development of fuel cells into viable products during the next decade, and there are already several hybrid vehicle designs successfully commercialized. The current electric drive configurations are susceptible to significant improvements with respect to weight and envelope dimensions versus torque and power capacity. This paper introduces a compact wheel end power unit concept that integrates advanced motor, package bearing, and gear technologies, and summarizes the development work related to its integration with the specific components of an automotive driveline.
Journal Article

Fuel Efficiency Improvements in Heavy Truck Wheel Systems through Advanced Bearing Design and Technology

2014-09-30
2014-01-2330
The base design of commercial vehicle wheel end systems has changed very little over the past 50 years. Current bearings for R-drive and trailer wheel end systems were designed between the 1920's and the 1960's and designs have essentially remained the same. Over the same period of time, considerable gains have been made in bearing design, manufacturing capabilities and materials science. These gains allow for the opportunity to significantly increase bearing load capacity and improve efficiency. Government emissions regulations and the need for fuel efficiency improvements in truck fleets are driving the opportunity for redesigned wheel end systems. The EPA and NHTSA standard requires up to 23% reduction in emissions and fuel consumption by 2017 relative to the 2010 baseline for heavy-duty tractor combinations.
Technical Paper

Enhanced Tapered Roller Bearing Performance

1987-11-08
871211
Tapered roller bearing performance has been enhanced through significant advances in bearing design, material quality, and manufacturing technology. These advances were made possible by the development of analysis methods and testing that pinpoint specific areas for improvement. As a result, maximum bearing performance can be achieved in smaller bearing designs or increased reliability can be realised within existing bearing sizes. Automotive and industrial designers have the opportunity to improve bearing application performance while accomplishing other objectives of lower weight and lower cost.
Technical Paper

Effect of Thermal Treatments and Carbon Potential on Bending Fatigue Performance of SAE 4320 Gear Steel

1999-03-01
1999-01-0603
This project investigated the effect of carburizing carbon-potential and thermal history on the bending fatigue performance of carburized SAE 4320 gear steel. Modified-Brugger cantilever bending fatigue specimens were carburized at carbon potentials of 0.60, 0.85, 1.05, and 1.25 wt. pct. carbon, and were either quenched and tempered or quenched, tempered, reheated, quenched, and tempered. The reheat treatment was designed to lower the solute carbon content in the case through the formation of transition carbides and refine the prior austenite grain size. Specimens were fatigue tested in a tension/tension cycle with a minimum to maximum stress ratio of 0.1. The bending fatigue results were correlated with case and core microstructures, hardness profiles, residual stress profiles, retained austenite profiles, and component distortion.
Technical Paper

Debris Signature Analysis: A Method for Assessing the Detrimental Effect of Specific Debris Contaminated Lubrication Environments

1998-04-08
981478
Various methods for evaluating the effectiveness of debris resistant bearings have been proposed for development. Once evaluation methods are well established to select bearings, the user is faced with assessing severity and detrimental effects of a specific application's lubricant contamination on bearing performance. Many analysis tools have been suggested for determining this impact, including particle analysis for size distribution, type of material and contamination level. A novel approach for determining severity of damage has been investigated which attempts to integrate these typical tools with actual damage to functional surfaces. It seeks to provide a practical approach and is appropriately labeled Debris Signature Analysis. Results of actual assessments will be discussed and the assessment method described.
Technical Paper

Assessing and Predicting the Performance of Bearings in Debris Contaminated Lubrication Environment

1999-09-13
1999-01-2791
Many lubrication environments in various equipment applications are inherently contaminated with debris and require mechanical components that are, as much as possible, resistant to the potential detrimental effects of debris particles. Many design engineers and lubricant specialists often overlook potential relationships between the various component failure modes, lubricant debris contamination level and the engineering solutions that are created to overcome them. Various methods for evaluating the effectiveness of debris resistant bearings have been proposed for development. Some of these methods have become standard methods within each bearing manufacturer's organization. Using an experimental method, performance evaluation results of tapered roller bearings in the areas of material fatigue will be discussed. The potential performance advantages will be placed in context of understanding the performance needs in the application.
Technical Paper

Air-Melted Steel With Ultra-Low Inclusion Stringer Content Further Improves Bearing Fatigue Life

1987-11-08
871208
Economical steels with improved fatigue life performance continue to be sought for more demanding applications such as in the automotive and aerospace industries. Researchers at The Timken Company, pursuing improved fatigue performance in tapered roller bearings, have found that life is limited by large inclusion stringers that still exist in today's highly publicized steels. Stringers, by definition, are clusters of individual oxide particles observable in wrought steel. An ultrasonic method has been used to quantify the frequency of these stringers in steel in bearing components. The total length of these stringers has been correlated with bearing fatigue life. The use of this ultrasonic tool has expedited the development of the newly introduced Parapretnium™ steel. This air-melted steel has a stringer content less than nearly all of the other worldwide bearing steels evaluated and, in fact, its stringer content is approaching those low levels found only in vacuum-remelted steels.
Technical Paper

A Bearing Life Prediction Method for Utilizing Progressive Functional Surface Damage Analysis from a Debris Contaminated Lubrication Environment

1999-09-13
1999-01-2793
Many lubrication environments in various equipment applications are inherently contaminated with debris and require mechanical components that are, as much as possible, resistant to the potential detrimental effects of debris particles. Many design engineers and lubricant specialists often overlook potential relationships between the various component failure modes, lubricant debris contamination levels, and engineering solutions that are created to overcome them. In addition, design engineers are in need of an analysis tool that can combine the various amounts of cumulative bearing damage occurring over time. As an example, bearing functional surfaces in many cases are progressively damaged over the life of the equipment. A new surface analysis tool is available which allows surface damage analysis to be completed at various stages of equipment life. This new surface analysis tool is appropriately called Debris Signature Analysis(sm).
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