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Automotive transmission design quality is generally judged by the vehicle's performance. Its acceleration, gradeability, maximum speed, terminal speeds, fuel economy and emissions provide these measures. These performance characteristics are optimized through the design process. This process, however, is iterative in nature and requires informed decision making to produce a design that is cost effective and excels in quality. In modern engineering, computer simulation plays an important role in the product design and development process. This paper provides a case study of the design and analysis of a heavy truck automatic transmission. It demonstrates the use of computer simulation models in generating and evaluating innovative design ideas.

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.

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.

Welding has been used extensively in automotive components design due to its flexibility to be applied in manufacturing, high structural strength and low cost. To improve fuel economy and reduce material cost, weight reduction by optimized structural design has been a high priority in auto industry. In the majority of heavy duty vehicle's chassis components design, the ability to predict the mechanical performance of welded joints is the key to success of structural optimization. FEA (finite element analysis) has been used in the industry to analyze welded parts. However, mesh sensitivity and material properties have been major issues due to geometry irregularity, metallurgical degradation of the base material, and inherent residual stress associated with welded joints. An approach, equilibrium-equivalent structural stress method, led by Battelle and through several joint industrial projects (JIP), has been developed.