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The impact of farm and industrial tractors on the total national emissions picture is difficult to assess because the great diversity of uses for these machines results in a wide variation in duty cycles and degrees of utilization. Also, there is a general lack of detailed information on population and population distribution. This paper compares possible farm tractor duty cycle models and concludes that the widely used 13-mode federal heavy-duty diesel engine emissions test cycle can be used to estimate wheel tractor emissions. Estimates then are given for the amount of pollution released by wheeled farm and industrial tractors in 1972, based on the 13-mode cycle and population estimates derived from U.S. Dept. of Commerce, U.S. Dept. of Agriculture, and Farm and Industrial Equipment Institute data. Calculations show wheeled tractor emissions contribute 3.2% or less of the national total, depending upon the pollutant species.

A method of developing a mathematical model of power-plants to simulate engine-governor, or servo systems on a d-c analog or digital differential analyzer is presented. Based on experimental data, the steady-state output of a powerplant is defined as a function of two variables. The dynamics is defined, and the steady-state performance is corrected for response and inertia effects. The resulting mathematical model is discussed with respect to computer applications, instrumentation, and techniques for compiling empirical data needed. Another application is monitoring performance of farm tractors, industrial equipment, and/or automotive systems under field operating conditions. The mathematical model is simulated by an analogous circuit of components that may be inconspicuously mounted on the powerplant in question.

THE NEW DIESEL ENGINES developed recently by International Harvester are adaptations of existing carbureted truck engines. The manufacturing economies possible by employing existing machine tools were the governing consideration in their design. This paper discusses solutions found to the many problems presented by this approach to engine design: crankshaft, crankcase, connecting rods, pistons, lubricating system, and the like. Extensive interchangeability of parts was a result of the design concept. The engines have been successfully adapted to farm tractors, crawler tractors, stationary motors, and various automotive applications.*