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This paper presents a six degree of freedom full vehicle model simulating the testing of heavy truck suspensions to evaluate the ride comfort and stability using actual characteristics of gas charged single tube shock absorbers. The model is developed using one of the commercial multi-body dynamics software packages, ADAMS. The model incorporates all sources of compliance: stiffness and damping with linear and non-linear characteristics. The front and the rear springs and dampers representing the suspension system were attached between the axles and the vehicle body. The front and the rear axles were attached to a wheel spindle assembly, which in turn was attached to the irregular drum wheel, simulating the road profile irregularities. As a result of the drum rotation, sudden vertical movements were induced in the vehicle suspension, due to the bumps and rebounds, thus simulating the road profile.

A concise method for modeling nonstationary fatigue loading histories is presented. The mininum number of model parameters is achieved by fitting the variations in mean and variance by a truncated Fourier series. An autoregressive moving average (ARMA) model is used to describe the stationary component. Justification of the method is made by comparing fatigue relevant parameters obtained when subjected to the original and reconstructed histories. In spite of a relatively small number of parameters required, the model is shown to give good results that fall within the bounds predicted by the orginal history.

Performance tests at full rack and 1400 rpm using a single cylinder diesel engine were made to determine the effects of three different micronized coal-fuel oil slurries being considered as alternative fuels. Slurries containing 20, 32, and 40 percent by weight micronized raw coal in No. 2 fuel oil were used. Results are presented indicating the changes in the fuel flow rates, concentrations of SOX and NOX in the exhaust, exhaust opacity, power and efficiency, and in wear rates relative to operation on fuel oil No. 2. The engine was operated for 10 hrs. on all fuels except the 40% by weight slurry. This test was discontinued because of extremely poor performance. Results indicate that the coal is largely inert in this situation and will cause a net increase in oil used and very rapid wear.