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A round-robin center of gravity height measurement study was conducted to assess current practice in the measurement of the vertical position of the center of gravity (c.g.) of light truck-type vehicles. The study was performed by UMTRI for the Motor Vehicle Manufacturers Association. The laboratories participating in the study were those of Chrysler Corporation, Ford Motor Company, General Motors Corporation, and the National Highway Traffic Safety Administration. The primary objectives of this study were (i) to determine to what extent the differing experimental procedures used by the participating laboratories at the time of the study result in significant differences in the measured vertical position of the center of mass of light truck-type vehicles, and (ii) to gain insight into the physical causes of such differences.

A full-scale vehicle testing program which emphasizes experimental determination of the rollover stability of double-bottom tanker configurations is discussed. The testing program is presented in the context of the total research program which included yaw plane and roll plane analytical studies. The baseline Michigan double-bottom tanker is found to have exceptionally low rollover stability in emergency evasive maneuvers. Vehicle modifications are described which improve stability by a factor of two. Test vehicle loading, anti-rollover outriggers, instrumentation, and modification hardware are discussed specifically. Results of dynamic handling tests and low-speed maneuverability tests are presented. Conclusions regarding the stability of individual vehicle configurations as well as overall fleet safety are reached.

The force-versus-deflection properties of truck leaf springs are studied with respect to the influences of motion amplitude and frequency (0 to 15 Hz) upon hysteretic damping and effective spring rate. Presented test results indicate that the energy loss per cycle of motion of a leaf spring is independent of the frequency of cycling. Measurements showing the influence of the amplitude of stroking are analyzed for five representative examples of currently employed leaf springs. A mathematical method for representing the force-versus-deflection characteristics of leaf springs is presented in a form suitable for use in digital simulations of vehicle dynamics.