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Debris particle contamination in lubricants has been identified as a major cause of premature bearing and gear failure, with accompanying costs in equipment downtime, warranty, and lost productivity. Various experimental and predictive methods have been developed to assist the design engineer in analysis and development of equipment that is less sensititive to such contamination. This paper provides an overview and new data comparing bearing life test results and predictive analysis methods for various tapered roller bearings operating under debris-contaminated conditions. As a baseline, some past work in these areas is briefly summarized and referenced. Recent work has refined one analytical method (using a surface characterization technique), correlated this method with bearing test lives in debris conditions, and pointed to design and manufacturing modifications in the bearings themselves, making the bearings live longer in debris-contaminated environments.

Tapered roller bearings have proven successful in a number of high-volume automatic transaxle designs. Typically, tapered roller bearings are required to carry high loads generated by helical and hypoid gears. To meet the demands of a successful design, a number of factors must be considered in the selection and application of tapered roller bearings. This paper presents a discussion of these factors as well as results from Chrysler's transaxle testing. Selection of tapered roller bearings is based on the transmission duty cycle developed using load and speed histograms, gear data, size constraints, and life requirements. A bearing life analysis considering the total transaxle system is conducted using a sophisticated computer program. Various system effects are analyzed including the load/speed cycle, housing and shaft rigidity, lubrication, bearing setting, thermal effects, and bearing internal design.

This paper describes the application of the Design for Manufacture and Assembly (DFMA) method at Chrysler. Attention is focused on the development of the clutch and brake pedal and bracketry system of the PL project in the Small Car Platform. The Chrysler DFMA procedure including competitive evaluation and value engineering was utilized during the initial design phase involving product concept development from the original functional and manufacturing requirements. After the first laboratory tests, a number of key design and manufacturing concerns surfaced and led to a second cycle of DFMA analysis. The procedure permits major design functions and manufacturing and assembly process issues and criteria to be incorporated in the initial design stages.

A unique opportunity arose to make a direct comparison of aluminum, sheet molding compound (SMC) and steel using a common hood design. In considering all possible material combinations of inner and outer panels, it was discovered that some of the combinations were incompatible due to material properties. Only the compatible material combinations were considered. Three different joining techniques - welding, bonding and bonded hem flanging - were evaluated. The cost, weight and structural performance of the chosen hood material combinations were established. Areas of further development were identified, including design optimization for specific material combinations.

A running loss test procedure has been developed which integrates a point-source collection method to measure fuel evaporative running loss from vehicles during their operation on the chassis dynamometer. The point-source method is part of a complete running loss test procedure which employs the combination of site-specific collection devices on the vehicle, and a sampling pump with sampling lines. Fugitive fuel vapor is drawn into these collectors which have been matched to characteristics of the vehicle and the test cell. The composite vapor sample is routed to a collection bag through an adaptation of the ordinary constant volume dilution system typically used for vehicle exhaust gas sampling. Analysis of the contents of such bags provides an accurate measure of the mass and species of running loss collected during each of three LA-4* driving cycles. Other running loss sampling methods were considered by the Auto-Oil Air Quality Improvement Research Program (AQIRP or Program).

A new electronically controlled transaxle has been put into production for Chrysler's family of LH cars. Among the attributes of this new transaxle are its ability to handle engines of high torque and high power coupled with high-speed shifts. Engine torque management is used in specific operating regimes. A feature of the transaxle is electronic modulation of the converter clutch. A number of logic features have been combined with hardware to provide good performance and shift quality over a wide operating range. An output transfer chain and a hypoid gear set are used to provide torque to the front wheels in a longitudinal power train orientation. Obtaining acceptable endurance life of the hypoid gears within an aluminum housing presented a significant challenge. New approaches were required to provide a chain-sprocket system with acceptable noise characteristics.

This paper describes how one American steel producer has been able to provide value which has benefitted the automotive industry in the past and how it is striving to provide value now and intends to do so for many decades into the future. As an alloy steel bar and tube manufacturer serving the automotive industry since its infancy, the Company has had to conquer many serious problems and challenges over the years. The current challenge is doing business as an American company in today's growing global society. In addition to overcoming the obstacles created by today's business environment, it will take continued innovativeness to provide value to the customer. THE THOUGHT OF MAKING STEEL probably never entered the mind of Henry Timken, the Company's founder, who spent most of his career producing carriages, buggies, and wagons. He was more concerned with friction in the axle bearings and what he could do to reduce it.

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.

As a cost effective solution to making microcontroller based systems “J1850[1] aware”, a peripheral device (the HIP7010) was developed to extend the capabilities of standard microcontrollers. From the perspective of the Host, the peripheral device handles J1850 messages as a series of bytes (similar in concept to a universal asynchronous receiver/transmitter [UART]). The architecture of the HIP7010 is discussed. The design of the J1850 interface, state machine, status/control blocks, cyclical redundancy check (CRC) hardware, host interface, and fail-safe features are detailed. Illustrations are provided of: Host/HIP7010 interfacing; message transmission and reception; error handling; and In-Frame Response (IFR) generation.

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.

Resistance to dents and dings, caused by plant handling and in-service use, is generally recognized as an important performance requirement for automotive outer body panels. This paper examines the dent resistance improvements that can be achieved by maximizing surface stretch, through adjustments to the press settings, and substitution of a higher strength steel grade. Initially, the stamping process was optimized using the steel supplied for production: a Ti/Nb-stabilized, ultra low carbon (ULC) grade. The stamping process was subsequently optimized with a Nb-stabilized, rephosphorized ULC steel, at various thicknesses. The formed panels were evaluated for percent surface stretch, percent thinning, in-panel yield strength after forming, and dent performance. The results showed that dent resistance can be significantly improved, even at a reduced steel thickness, thus demonstrating a potential for weight savings.

Fastener failure due to hydrogen embrittlement is of significant concern in the automotive industry. These types of failures occur unexpectedly. They may be very costly to the automotive company and fastener supplier, not only monetarily, but also in terms of customer satisfaction and safety. This paper is an overview of a program which one automotive company initiated to minimize hydrogen embrittlement in fasteners. The objectives of the program were two-fold. One was to obtain a better understanding of the hydrogen embrittlement phenomena as it relates to automotive fastener materials and processes. The second and most important objective, was to eliminate hydrogen embrittlement failures in vehicles. Early program efforts concentrated on a review of fastener applications and corrosion protection systems to optimize coated fasteners for hydrogen embrittlement resistance.

The commercial validation of a optimized RRIM polyurethane substrate with a novel barrier coat for fascia applications is reviewed which creates cost competitiveness to thermoplastic olefins (TPO), without sacrificing performance. Meeting fascia performance requirements with thinner and lighter RRIM materials containing recyclate and the subsequent application of a barrier coat eliminating the traditional primecoat cycle was investigated.

To understand how the passenger compartment cavity interacts with the surrounding panels (roof, windshield, dash panel, etc) a numerical panel contribution analysis was performed using FEA and BEA techniques. An experimental panel contribution analysis was conducted by Reiter Automotive Systems. Test results showed good correlation with the simulation results. After gaining some insight into panel contributions for power train noise, an attempt was made to introduce beads in panels to reduce vibration levels. A fully trimmed body structural-acoustic FEA model was used in this analysis. A network of massless beam elements was created in the model. This full structural-acoustic FEA model was then used to determine the optimal location for the beads, using the added beams as optimization variables.

Improved fuel economy translates into significant savings over the life of a fleet vehicle. Aside from fuel cost savings, tighter emissions regulations require truck Original Equipment Manufacturers (OEMs) to improve the fuel economy of the products they bring to market. OEMs are dependent on Tier 1 suppliers for many systems which have a direct impact on vehicle fuel efficiency. Tier 1 suppliers are then dependent on sub-suppliers for components which affect the fuel efficiency of the system. Improvements in tapered roller bearing design and technology can significantly improve the fuel efficiency of driveline systems. This paper summarizes the improvement in bearing efficiency by applying advanced design and technology solutions. Analysis was used to predict the affect of design changes, leading to an optimized solution. Testing was performed to verify the improvement in bearing efficiency.

Automated bearing setting techniques have been developed to insure economy and reliability with regard to the assembly and setting of tapered roller bearings in a wide variety of machinery and equipment. The application of these concepts is designed to minimize or eliminate the human variable of judgment and skill during the assembly operation. The full effectiveness of these concepts can be utilized only if machinery is properly designed to accommodate these methods. Emphasis will be placed on design considerations to achieve this end. Various setting techniques will be presented that are currently being used successfully on a production basis.

THE Junkers 211B engine follows the usual German practice of very large displacements and conservative mean effective pressures and rotative speeds. However, the relative light weight per unit of displacement results in a net weight per horsepower that is not far above its competitors. Fully automatic devices which control propeller speed, manifold pressure, mixture ratio, spark advance, and supercharger gear ratio follow the German policy of removing all possible distractions from the pilot. This is one of three large liquid-cooled engines known to be produced in quantity in Germany; it powers an impressive percentage of the Luftwaffe. While of external appearance and displacement that resemble the Daimler-Benz DB-601 engine, the fundamental construction, detail design practice, and metallurgy of the Junkers 211B are surprisingly different.

Automotive wheel and brake engineers are studying various wheel bearing concepts which lend themselves to easy installation and reduction of unsprung weight. A family of tapered roller bearing designs has been developed for both driving and non-driving wheels which offer the industry several options for marrying suspension, wheel and bearing components. While differing in configuration, all may be selected to meet established criteria for satisfactory performance based on the latest bearing analysis techniques and experience derived from extensive laboratory and field test programs.

Advances in computer technology and the published results of extensive bearing research and empirical testing, have allowed designers to expand the traditional catalog approach and optimize the selection process for tapered roller bearings. This paper explores many of the factors influencing bearing selection where fatigue life is the primary concern, and describes how the Bearing Systems Analysis (BSA) approach, as used by The Timken Company, incorporates the effect of many of these environmental variables. Particular attention is paid to the formation and analysis of the load-speed spectrum, or histogram, and to the vital part it plays in the bearing selection process.