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This paper derives a parametric equation for predicting the fuel economy of on-highway heavy-duty trucks. The accuracy of this equation is compared to actual vehicle MPG results. Based on this equation, the relative importance of the numerous parameters which affect the fuel economy of on-highway heavy-duty vehicles are calculated and discussed. To illustrate the value of this methodology, the development of the newest Freightliner EnergySaver package is described and the results from a cross-country fuel economy test of this package are presented. Using these same methods, the future for increasing on-highway heavy-duty truck fuel economy is explored.

Since the introduction of the Freightliner/Wabco individual wheel control ABS in 1987, both Freightliner and Wabco have continued their efforts to develop a simplified and highly cost effective ABS for use on Freightliner vehicles. This ongoing development effort has lead to the 4-channel Freightliner/Wabco Tandem Control ABS. This new Freightliner/Wabco Tandem Control ABS was introduced in 1989 as an alternative to the original Freightliner/Wabco 6-channel individual wheel control ABS for use on typical 3 axle, on highway, tractors and trucks. This paper describes the advantages and the differences between the Freightliner/Wabco 6-channel individual wheel control and the Freightliner/Wabco 4-channel Tandem Control ABS when installed on 3 axle Freightliner vehicles.

Dividing a vehicle pass-by test into a series of short analysis intervals and calculating a spectra for each of these intervals can provide meaningful information to help identify individual noise sources throughout the pass-by test. Due to the continuously changing instantaneous frequency and amplitude of each of the tonal components in pass-by noise data inaccuracies can occur in the spectra calculated in this manner. The questions which are addressed in this report are the selection of the frequency resolution and block size for FFT processing of pass-by test data to provide a power spectrum with acceptable accuracy for noise source identification.

A system for analyzing results from vehicle pass-by noise tests is presented. Features of the system include data telemetry, narrow band frequency analysis, order analysis, portability and efficient data management through the use of computer based data reduction and display graphics. The system has been implemented and utilized in a development program for reduction of noise emissions from heavy-duty diesel trucks.

This article reviews the fundamentals of vibration theory and discusses how the concepts used in describing the motion of single mass-spring-damper system can be extended to describe the motion of structures and systems via modal analysis. The material presented progresses from a discussion of a single mass-spring-damper system to modal properties of multi degree of freedom systems to frequency response and mode superposition methods. Although these techniques are not new, the intent is to present the fundamentals of modal analysis for those not already well acquainted with the theory and techniques involved.