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

SAE International Journal of Commercial Vehicles

The Timken Company-Matt Zwick
  • Journal Article
  • 2014-01-2330
Published 2014-09-30 by SAE International in United States
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.This paper summarizes the history of current wheel end bearing designs and the opportunity for change to lighter-weight, cooler-running and more fuel-efficient wheel bearing designs to help meet the new industry standards. Advanced design and modeling principles were applied to analyze improvements, leading to optimized designs. Physical testing validated that these new bearing…
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Repair as an Option to Extend Bearing Life and Performance

The Timken Company-Michael N. Kotzalas, Matthew R. Eckels
Published 2007-10-30 by SAE International in United States
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. The life predicted using the new model is compared to life test data of repaired tapered roller bearings for model confirmation. Finally, an example of how the new method can be used on a…
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Improving the Performance of Rolling Element Bearings with Nanocomposite Tribological Coatings

The Timken Company-Gary L. Doll
Published 2006-10-31 by SAE International in United States
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.
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Mechatronic Torque Vectoring System with Enhanced Controllability for Augmenting the Vehicle Agility and Safety

The Timken Company-John Feltman, John Ganley, Stuart Hamilton, Mircea Gradu
Published 2006-04-03 by SAE International in United States
This paper describes an advanced vehicle dynamics and traction control system, using magnetic-powder clutch technology combined with planetary gear sets.
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The Impact of Some Gear Lubricants on the Surface Durability of Rolling Element Bearings

The Timken Company-Harvey P. Nixon
Published 2006-04-03 by SAE International in United States
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.
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Methods for Assessing the Bearing Surface Durability Performance of Lubricant Formulations

The Timken Company-Harvey P. Nixon
Published 2005-10-24 by SAE International in United States
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. The implications of these findings provide direction and suggestions for ways to minimize or avoid potential detrimental performance effects of lubricant formulations on rolling element bearings.
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An Electro-Mechanical Infinitely Variable Transmission for Hybrid Electric Vehicles

The Timken Company-Xiaolan Ai
Ricardo Inc-Scott Anderson
Published 2005-04-11 by SAE International in United States
An electro-mechanical variable speed transmission (eVT) is proposed for hybrid electric vehicles. The transmission is comprised of a pair of planetary gear trains interconnected with two electric machines and clutches. With on-board energy storage devices, the transmission combines, in a compact unit, independent speed-ratio control and power regulation between the engine and drive wheels. It offers a highly integrated, efficient and low cost solution to hybrid electric vehicles.Operating principles of the transmission were outlined. Virtual transmission and vehicle prototypes were built with EASY5. Simulations were conducted to evaluate its performance in context of a hybrid electric vehicle. Comparisons were made against non-hybrid vehicles equipped respectively with eVT and four-speed automatic transmission, and against the production hybrid vehicle Prius.Results showed superior performance of the proposed eVT in hybrid vehicle. It improved vehicle acceleration and significantly reduced fuel consumptions comparing to the non-hybrid vehicles. The fuel economy improvements were 158% for FTP cycle and 92% for HWFET cycle over the non-hybrid vehicle with four speed automatic transmission.Simulation indicated that the hybrid vehicle with eVT offers considerable technical…
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Increased Life/Noise Reduction of Mechanical Components by Applying Topographical Imagery and Surface Mapping Methodology

The Timken Company-Steve Tornero, Mark R. Moldovan, J. David Cogdell
Published 2004-11-16 by SAE International in United States
The Timken Company performed a detailed study involving topographical imagery and surface mapping. The primary purpose of the study was to develop a direct correlation between surface topography and component durability/life. Through these studies, an optimal surface finish was developed. A production environment was then formed to mass-produce components with this finish on a contact-to-contact component. The results of the study guide us to an increase in durability/life of the Timken product. The paper is divided into three sections.The first section describes the component itself and the testing procedures by which durability/life were determined. The second section describes the analytical work done at the Timken Research facility where topographical imagery and surface mapping were performed. At this time, topographical analysis of several surface finishes paved the way to create an optimal surface texture for increased durability/life. Next, brainstorming was conducted to transform the desired surface texture from laboratory to production environment. The third section describes the actual tools and techniques put in place in the production environment to achieve the desired surface texture. Precision Steel…
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Highly Compact Electric Drive for Automotive Applications

The Timken Company-Rao S. Zhou, Fukuo Hashimoto
Published 2004-10-25 by SAE International in United States
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. The resultant electric drive is evaluated under different technical and commercial criteria, including performance, power density, ease of assembly, complexity and cost. Based on both analytical model predictions and performance test results, the wheel-end electric drives presented in the paper are very well suited for a wide range of vehicle platforms, as compact…
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An Electro-Mechanical Infinitely Variable Speed Transmission

The Timken Company-Xiaolan Ai, Terry Mohr
Ricardo, Inc.-Scott Anderson
Published 2004-03-08 by SAE International in United States
An electro-mechanical infinitely variable transmission (eVT), comprising a pair of planetary trains interconnected with two electric machines and clutches, has been proposed. The transmission leverages the advantages of an output power-split configuration for low-speed operation and a compound power-split configuration for high-speed operation. It is capable of being operated in a number of operating modes including an eVT only mode and a hybrid mode when equipped with on-board energy storage devices. The transmission provides a compact, highly efficient and potentially low cost driveline solution for both conventional vehicles and hybrid electric vehicles.A virtual transmission prototype was built in EASY51. A base vehicle model was also constructed in EASY5 environment with Ricardo Powertrain Library components. Performance of the proposed transmission was evaluated in context of the base vehicle for driveline efficiency, vehicle acceleration, vehicle fuel consumption and emissions under various driving cycles. Comparison with a conventional four-speed automatic transmission was made.Results of the evaluation have demonstrated superior performance of the proposed eVT over conventional automatic transmissions. The eVT has a high efficiency of 92% over most…
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