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This paper describes a method of vehicle performance prediction which adapts readily to digital programming. A prime mover which may be a gas turbine or a reciprocating internal combustion engine, a hydraulic torque converter, and/or a mechanical transmission, comprising the vehicle drive train, are transformed into numerical equivalents. The performance prediction itself is in three major parts, namely, the engine-converter compatibility, the converter range performance, and the lockout or direct drive performance. The computer transforms the engine data into equation form by curve fitting; predicts the optimum shift point as the intersection of the net tractive effort in converter drive with net tractive effort in direct drive; calculates; stores; interpolates; and prints a complete set of data.

THE INCREASED use of midship-mounted transmissions in large equipment has emphasized the need for a torsionally resilient connection from the engine to reduce vibration transfer. To increase the torsional flexibility needed in these systems, the spring rate of the system must be reduced by such constructions as a flexible coupling, a spring-loaded damper, or a rubber torsional spring. This paper discusses these systems, emphasizing rubber springs. Some advantages of such a drive are: it provides an amplitude limitation with impact loads and a cushion to reduce noise and prevent clattering and contacts noises on parts with backlash, it smooths out transition periods to reduce loads on bearings and gears, its clamping characteristics can be adjusted by various rubbers, and its rubber cushion provides a degree axial flexibility.*

This is a study of driveline torque associated with re-tarders when used as a means of controlling vehicle downhill speed. Using two commercially available retarders for field testing, the working principle and driving method for each is briefly explained. Data compiled from field tests is summarized in chart form providing a direct comparison between ascending driveline torque and the torque imposed on the driveline when descending the same hill, using a hydraulic driveline retarder, an engine retarder, or service brakes. The resulting comparison provides the basic guide for the design and evaluation of present components used in conjunction with retarders.

A new series of truck transmission has been developed with the intent of customizing the ratios to the engine and the job. Two years of laboratory and field testing has been completed on these transmissions, proving their reliability and performance. This paper covers the development of a new series of heavy duty truck transmissions utilizing the split torque concept of power flow. A chronicle of the development is set forth, as well as an assessment of the most salient features of this series of transmissions. A statement of the present status of the transmission series also is presented.

The transmissibility technique has been traditionally used for evaluating the NVH performance of isolated, rigid structures such as the elastomer mount isolated automobile engine. The transmissibility quantity provides information on how a structure reduces vibration as subjected to dynamic loading and thereby attenuates noise. In the present study, the transmissibility is applied to a non-rigid, plastic structure - the engine cylinder-head cover module. The cover module includes primarily a thin, plate-like cover and the elastomer isolation system. At low frequencies, the cover will behave as a rigid mass and thus display a major peak at its resonant frequency. At high frequencies, the cover will vibrate as a flexible panel and thus display multiple peaks with magnitudes differing from point to point across the cover surface. As a result, the transmissibility calculated would have a spatial resolution, called the spatial transmissibility.

A turbine engine powered vehicle requires a power transmission system with distinct differences over one required with other powerplants. The power transmission components can be modified to accommodate the new requirements. As turbine engines become more popular a more optimum approach to power transmissions is needed. Some reasonable possibilities are discussed. The manner in which components have been applied and the results obtained along with future possibilities are covered in the area of clutches, mechanical transmissions, and drivelines and axles.

Thermoplastics have been used increasingly for automobile components for both interior and under-the-hood applications. The plastic parts are made through various molding process such as compression molding, injection molding and blow molding. For parts with large or complicated geometry, small portions of the part may have to be molded first, then joined together using a welding process. The welded regions usually exhibit inhomogeneous and inferior mechanical performance compared to the bulk regions due to the differences in thermal history. The microstructures and mechanical properties of welded thermoplastics have been examined using hot-plate welded polyethylene. The specimens are prepared at various thermal conditions to simulate the real welding process. The thermal properties in welds are monitored using DSC (Differential Scanning Calorimetry) and the crystallinities are calculated.

A major challenge in predicting driveline torsionals is the modeling of major energy dissipation mechanisms in the driveline. Primary candidates for such mechanisms are viscous dampers and dry friction (hysteresis) dampers which are specifically included by the designers to disperse the energy of torsional vibrations. The inherent structural and other internal damping in the components of the driveline is small as compared to those of viscous and dry friction dampers. Past attempts to model clutch hysteresis have repeatedly resorted to the classical approach of modeling that has been reported many years ago. However, such an approach is oversimplified and assumes, for instance, that the hysteretic effects are independent of the frequency. In addition, the motion of the damper is assumed to be purely harmonic. Also, such studies rely solely upon the static hysteresis characterization of the elements, particularly within the clutch.

The present research constitutes an engineering approach to the performance level prediction of starting a vehicle without use of a throttle. The study is based on a dynamic clutch engagement model. A computer simulation of engagement dynamics is used in order to study the lock-up mechanism and to develop proper prediction procedures. In addition, the engagement model is used to develop guidelines and recommendations in order to optimize the engagement system including clutch components, clutch controls, and engine controls. The mathematical model presented in this paper incorporates important, new features in comparison to similar models from previous publications. Consisting of two inertias, it includes not only elastic properties of the clutch damper but also varying engine torque and clamping (pressure) force. Functions of engine torque and plate load simulate the actual control process, including human factors.

A detailed methodology is presented in this paper for a complete assessment of various forces, torques, and kinematic effects due to universal joint angularities and shaft yoke phasing. A modular approach has been adopted wherein constitutive equations represent each of the key elements of a driveline namely the driveshaft, coupling shaft, universal joint, and the transmission/axle shafts. Concentrated loads are used wherever loads are being transferred between the elements of a driveline. Local matrices are developed for the equilibrium of the respective driveline members. The local matrices are then assembled into a global matrix and solved for the kinematic state of the complete driveline. A 6x15 matrix has been developed to represent a general shaft in the system and a 6x10 matrix has been developed for a universal joint cross. This gives us a complete picture of all the loads on all driveline members.

Microalloyed (MA) steels have been developed as economical alternatives to the traditional quenched and tempered (QT) steels. The physical metallurgy principles underlying their basic composition-processing-microstructure-property interrelationships have been reviewed in the first part of the review. In this second part of the review, mechanical properties as well as fabrication properties, such as mahinability, weldability, and formability, are discussed. Flat products (such as strips, sheets, and plates), long products (including bars, rods, sections/profiles), and forging articles made of MA steels are investigated. Since most engineering components made of these steels are subjected to cyclic loading, fatigue and fracture performance of MA steels and their comparison with the QT steels are also evaluated in this review.

Microalloyed (MA) steels have been developed as one of the most significant metallurgical advances over the last thirty years, with their property improvement and cost effectiveness characteristics. Even though the underlying principles for microstructural property control of these steels have been well established, applications of these steels are still limited in scale mainly due to a lack of their understanding. This review paper focuses on mechanical property control of these steels. Since the properties depend mainly on the composition and microstructure which in turn are controlled by steel making and processing, metallurgical variables are reviewed in this first part of the review. These include their strengthening mechanisms, effects of composition and processing on their behavior, and the various MA steel microstructures.