Search Results

Can you become a visionary or are you born one? How does a visionary capture an opportunity and makes it a successful business? Are engineers more qualified to solve technical problems or run companies? SAE's "The Visionary's Take" addresses these and many other questions, by talking directly with those who have dared to tackle difficult engineering problems, and create real-life products out of their experience. In these short episodes, Sanjiv Singh and Lyle Chamberlain, respectively CEO and Chief Engineer from Near Earth Autonomy, talk about their experience in creating a brand-new company in the UAV world. Founded in 2011, Near Earth Autonomy brought together a group of engineers and roboticists, looking for unconventional solutions to very hard logistics problems, presenting danger to human life. The answers were developed by pushing technology to a higher level, testing quickly and often, and keeping an open mind to alternative ways of framing engineering challenges.

Can you become a visionary or are you born one? How does a visionary capture an opportunity and makes it a successful business? Are engineers more qualified to solve technical problems or run companies? SAE's "The Visionary's Take" addresses these and many other questions, by talking directly with those who have dared to tackle difficult engineering problems, and create real-life products out of their experience. In these short episodes, Sanjiv Singh and Lyle Chamberlain, respectively CEO and Chief Engineer from Near Earth Autonomy, talk about their experience in creating a brand-new company in the UAV world. Founded in 2011, Near Earth Autonomy brought together a group of engineers and roboticists, looking for unconventional solutions to very hard logistics problems, presenting danger to human life. The answers were developed by pushing technology to a higher level, testing quickly and often, and keeping an open mind to alternative ways of framing engineering challenges.

Patents granted recently to Mr. Rode have changed the industry capability to adjust and verify wheel-end bearings on trucks. Until now it was believed1 that there was nothing available to confirm or verify the most desirable settings of preload on these bearings. The new, breakthrough invention is a tool and spindle-locking nut that permit quick and accurate wheel bearing adjustment by utilizing direct reading force measurement. Bearings can be set to either SAE recommended preloads or specific endplay settings. The author has been working on bearing adjustment methods for industrial applications for over forty years, and considers these inventions to be his most important breakthrough for solving this elusive bearing adjustment problem. Consistent wheel bearing preload adjustment was not possible before, even though it was widely known to achieve the best wheel performance as noted in SAE specification J2535 and re-affirmed in 2006 by the SAE Truck and Bus Wheel Subcommittee.

Coatings have the potential to improve bearing tribological performance. However, every coating application process and material combination may create different residual stresses and coating microstructures, and their effect on bearing fatigue and wear performance is unclear. The aim of this work is to investigate coating induced residual stress effects on bearing failure indicators using a microstructural contact mechanics (MSCM) finite element (FE) model. The MSCM FE model consists of a two-dimensional FE model of a coated bearing surface under sliding contact where individual grains are represented by FE domains. Interactions between FE domains are represented using contact element pairs. Unique to this layered rolling contact FE model is the use of polycrystalline material models to represent realistic bearing and coating microstructural behavior. The MSCM FE model was compared to a second non-microstructural contact mechanics (non-MSCM) model.

The 9-meter wind tunnel of the National Research Council (NRC) of Canada is equipped with a boundary layer suction system, center belt and wheel rollers to simulate ground motion relative to test articles. Although these systems were originally commissioned for testing of full-scale automotive models, they are appropriately sized for ground simulation with half-scale tractor-trailer combinations. The size of the tunnel presents an opportunity to test half-scale commercial vehicles at full-scale Reynolds numbers with a model that occupies 3% of the test section cross-sectional area. This study looks at the effects of ground simulation on the force and pressure data of a half-scale model with rotating tractor wheels. A series of model changes, typical of a drag reduction program, were undertaken and each configuration was tested with both a fixed floor and with full-ground simulation to evaluate the effects of this technology on the total and incremental drag coefficients.

The present competitive market scenario and customer requirements demand for improved NVH quality and to meet statutory norms without increased cost. When gears are used for power transmission, gear noise is of particular concern. The noise may be created due to harmonics of the rotating and meshing internal components. This has a significant effect on the overall vehicle sound quality. Various factors contribute to gearbox noise. Some of them include shaft misalignments, gear geometry, lubrication, bearings and loose mountings. Hence it is essential to study which factors contribute to the gearbox noise and to develop countermeasures for the same. Although a number of factors may contribute to gear noise as mentioned, the scope of this paper is limited to the effect of gear geometry alone on the gearbox noise.

Adjuster rings are used in commercial vehicle axle assembly to preload differential bearings and provide support in the axial direction. Adjuster along with the carrier and bearing cap combined to form a threaded joint. Adjuster with external threads engages with internal threads formed in carrier and bearing cap. Preload in differential assembly maintains the system rigidity and helps to maintain an optimized hypoid gear engagement. An adequate preload is important to achieve a desirable bearing life. Reduction in thread engagement at adjuster joint fully or partially will cause a reduction in preload and can lead to gear misalignment. This can cause severe durability concerns. In some cases, it is observed that under vehicle operating loads adjuster ring is backed off from its assembled condition by bending the split pin (split pin is, positive lock, used to maintain adjuster position) and adjuster threads were stripped off.

The impact of Reynolds number on the aerodynamics and operational performance of commercial vehicles is discussed. All supporting data has been obtained from published experimental and computational studies for complete vehicles and vehicle components. A review of Reynolds number effects on boundary layer state, unsteady and steady flow, time dependent wake structure, interacting shear layer and separated flows is presented. Reynolds number modeling and simulation criteria that impact aerodynamic characteristics and performance of a commercial vehicle are shown. The concepts of dimensional analysis and flow similarity are employed to show that aerodynamics of commercial ground vehicles is only dependent on Reynolds number. The terminology of Roshko is adopted for discussing the variation in drag with Reynolds number in which the subcritical, transitional and transcritical flow regimes are defined for commercial vehicles.

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 document establishes the requirements for technical content and format of hydraulic system diagrams. This document does not establish configuration requirements, material, or performance requirements for any system or component identified herein.

This SAE Standard applies to machines as defined in Appendix A. Some of these machines can travel on-highway, but function primarily off-highway.

This SAE Standard applies to machines as defined in Appendix A. Some of these machines can travel on-highway, but function primarily off-highway.

This SAE Recommended Practice describes STANDARD-DUTY and EXTREME-DUTY Pilot Bearing requirements and sizes for class 6, 7, and 8 on-highway trucks and buses that use diesel engines and manual transmissions. The recommendations may apply to a wide range of other pilot-bearing applications, such as agricultural, industrial, and construction equipment.

This SAE Recommended Practice describes STANDARD-DUTY and EXTREME-DUTY Pilot Bearing requirements and sizes for class 6, 7, and 8 on-highway trucks and buses that use diesel engines and manual transmissions. The recommendations may apply to a wide range of other pilot-bearing applications, such as agricultural, industrial, and construction equipment.

The paper was originally published with the authors in the incorrect order. The correct author order should be as follows: Charlotte Fossier, Université de Lyon Dennis Barday, Volvo Group Christophe Changenet, Université de Lyon Fabrice Ville, Université de Lyon Vincent Berier, Volvo Group

A small sample lot of Conrad type ball bearings fabricated of silicon nitride have been fatigue tested under full film liquid lubrication conditions. Analysis of the failed bearings points to a failure mechanism which is different than that of steel bearing fatigue. A failure model has been developed based on the static strength of the material, manufacturing process effects and basic contact mechanics. The failure mode found identifies one limitation of the use of ceramic bearings. The limitation is dictated by the tensile stresses produced in operation and the strength of the finished component. It was demonstrated that silicon nitride fails by mechanical fatigue when subject to high Hertzian contact stress. It must be clearly understood, however, that the high Hertzian contact stresses (above 350 k.s.i.) used in this test program are greater than those of recommended design practice. The bearing manufacturing, testing and failure analysis are discussed.

In order to optimize bearing performance in the 21st Century, bearing life prediction will need to consider bearing ratings (the starting point), the actual environmental conditions in which bearings will operate and will need to identify the appropriate adjustment bridge in order to go from rating life to realistic application life. Generic ratings, as published in Standards, are described in this paper as well as specific ratings for a single type bearing based on explicit, experimentally determined parameters. Life adjustment factors are then discussed covering both the Bearing standards' a1, a2, a3 approach and a more comprehensive life adjustment approach that recognizes the interdependency of the various adjustment factors, subfactors, and the load-life relationship. This concept is demonstrated with tapered roller bearing examples and experimental support for improved bearing life prediction in the more demanding application environments of the future.

Pinion bearing loads of a heavy duty rear truck axle were determined by Finite Element Method Analysis (FEM). The results were compared with measured loads. This report describes the method used to measure bearing loads, the FEM model used, and the comparison of the results.

This SAE Standard applies to future designs of self-propelled, rubber-tired loaders, tractors, graders, backhoe loaders, tractor-scrapers, excavators, and dumpers as defined in SAE J1057 JUN81.

This document specifies the format, content and parameters for a product identification numbering system for off-road recreation vehicles, based on the PIN structure for earth-moving machinery in ISO 10261:2002E and is not applicable to the identification of components or attachments. This standard applies only to the off-road recreation vehicle industry and does not impose parameters for the marine, lawn and garden, silviculture, husbandry, construction or earth moving sectors.