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This paper describes an analytical process for the design of a brake shoe assembly that consists of the linings, shoe table, webs, and rivets. One fundamental performance requirement for the brake shoe assembly is that the linings will not lose clamp force within the desired service life. Key elements of the analytical process involved developing an FEA model with given loading conditions and developing a mathematical model to study the influence parameters of the forces acting on the lining.

Engineering specifications, i.e. test bogeys, are criterion for determining the success or failure of durability designs in the product development process. Considerations in the development of the specifications for vehicle structural components, such as axle housings and suspension torque rods, have been presented in a previous SAE paper [1]. This paper has been prepared because the factors on the same subject for vehicle drive train components, such as gears and bearings, are quite different. The center of this study is on “how to define equivalent duty cycles for lab test”. Several issues distinguish this task for drive train components: High cycle fatigue, high accelerated tests, competitive failures and failure modes, empirical component load-life data, loading, field correlation, and system level tests.

Only products with high quality, low cost, and short concept-to-customer time will continue to have a high market share. For this reason, auto parts suppliers must strive to gain superior engineering capability. One key step in this pursuit is to implement widespread CAE (Computer-Aided-Engineering) in PDP (product development process) [1]. FEA (Finite Element Analysis), in particular, has been identified as a subject that deserves concentrated effort. Specifically, FEA needs to be used broadly and effectively in every phase of PDP ranging from concept evaluation and prototyping, to pre-production design and troubleshooting. However, resource requirement and process quality assurance are major issues in this undertaking [2, 3]. As a counter-measurement, developing product specific FEA guidelines has been identified as a priority strategic initiative. The focus of our presentation is on how to develop standard FEA procedures to guide FEA jobs.

Nowadays, developing web (World Wide Web) engineering is considered to be a top priority task in many companies. A corporate web information center with broad coverage to support a company's worldwide engineering activities can make the product development and customer support more efficient. First, the archived, readily available product information, knowledge database, and user friendly engineering tools can ease up the more ever demanding engineering jobs. Second, the convenient information storage, retrieval systems and hyperlinks on the web should ensure effective communications among engineers, customers, and suppliers. However, without in-depth planning, the full benefits of web engineering cannot be realized. To be effective, other companion engineering programs must also be instated. This paper reviews the experience we have gained in utilizing web engineering for product development and customer support.

In recent years, several transit agencies have tested buses equipped with hybrid powertrain systems. It has been reported that hybrid powertrains have significant advantages over conventional diesel engine systems, in the area of emissions and fuel economy performance. Presented in this paper are engineering issues and suggestions from an auto component supplier point of view in the design of such a powertrain system. The particular system being considered consists of a downsized diesel engine, a generator, a battery package, two identical AC induction motors, and gearbox systems for the left and right driven wheels. The assembly is supported by an H-shaped suspension sub-structure uniquely designed to achieve the “ultra-low floor” configuration. Our discussion covers the system performance, as well as the durability issues. In particular, the presentation focuses on the durability and the design layout of the gearbox and suspension substructure.

Premature parts breakdown in the final drive of heavy vehicle powertrains in vehicles equipped with high power retarders leads one to believe that the coasting mode gear forces may be higher than anticipated. There is limited experimental data that supports this hypothesis in the observation of high bearing load and gear bending stress in coast mode. However, without an in-depth analysis, it is unclear exactly how the high load is generated. There are several suggested causes: friction, gear geometry, and system compliance. The present study focuses on the effects of hypoid gear friction on the powertrain. Analytical expressions of the gear friction vector as a function of gear pressure, pitch and spiral angles, spiral hand and directions of rotation and applied torque were derived and examined. Attempts were made to correlate test-measured quantities and results from analytical models with and without the consideration of gear friction.

Although the methodology of straight bevel gear tooth form generation has been known for quite some time, few references are available in the literature. Presented in this paper are the general numerical procedures of spherical involute and octoid tooth form generations. We have proven that a tooth form generated from the latter approach, by simulating the rotation of a crown gear, matches exactly with the one from the former approach of unwraping a wire from a base circle. The advantage of using general numerical procedures rather than closed form equations is the flexibility of generating both standard and modified gear tooth profiles. In making the forging die, the gear tooth form must be developed with considerations of both the theoretical optimal geometry, and the dimensional compensation for heat treatment distortion.

The uniqueness of heavy and medium duty vehicle powertrain design, compared to that of passenger cars, is two fold: vast variations exist from vehicle to vehicle because of mission requirements, and powertrain components are sourced from a diverse group of suppliers. Vehicle powertrain design involves selection of the appropriate major components, such as the engine, clutch, transmission, driveline, and axle. At this design stage the main focus is on power matching, to ensure that the vehicle's performance meets specifications of gradability, maximum speed, acceleration, fuel economy, and emissions[1, 2, 3, 4 and 5]. The general practice also demands that the durability of the drivetrain components for the intended vocation or application be verified. Equally important but often neglected in the design phase is the system's NVH (Noise Vibration and Harshness) performance, such as torsional vibration, U-joint excitation, and gear rattle.