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A diaphragm-type, strain-gage, surface-slope sensor has been designed for off-road vehicles. The sensor is capable of continuously measuring surface slopes in longitudinal and lateral directions simultaneously. Instrumentation amplifiers with low-pass filters were used for signal processing. Laboratory tests showed that the sensor had satisfactory sensitivity, linearity, and dynamic characteristics. Potential applications of the slope sensor include studies of vehicle mobility, stability, tractive performance, and safety.

Tractive efficiency (TE) and lateral stability were testes on a DewEze MC70 highway mower with three types of tires under two different inflation pressures. A data acquisition system was developed to measure 12 variables including surface slopes in the longitudinal and lateral directions. Results of field tests showed that one tire type outperformed the other two types and the lower inflation outperformed the higher inflation pressure in TE. The tests on side slopes showed no significant difference in lateral stability among the three types of tires or between two inflation pressures.

Current energy supplies are finite and are being used at an ever increasing rate. We can no longer evaluate alternatives on a cost basis alone. Crop production systems are no exception. We must now evaluate such systems on energy-use and environmental impact bases as well as on a cost basis. This study was to develop and compare energy budgets for wheat, grain sorghum, and wheat-grain sorghum rotation tillage systems. Energy inputs considered included machinery and parts manufacturing, crop production fuel, and tire and herbicide manufacturing. Our results show that energy requirements for crop production tillage systems vary considerably. Fuel consumed by tractors in performing the tillage operations was the largest input (39.6-82.5% of the total). Energy for herbicide, however, was almost as large as the fuel input for the grain sorghum no-till system. No-till systems use slightly more energy than till-plant tillage systems for grain sorghum (60.8 versus 54.5% of conventional).

The Purdue Univ. soil-vehicle laboratory located in the Agricultural Engineering Building was used to study the effect of dual, single, and tandem drives on artificial soils. The dual versus single tire comparisons were made with 4.00 × 8 tires. Two tandem drive combinations were used. The first combination utilized 4.00 × 8 tires for both the front and rear wheels, and the second combination used a 4.00 × 8 tire for the front wheel and a 6.00 × 12 tire for the rear wheel. Dual tires performed better than single wheels of the same weight when tested on loose soils. The full advantage of dual tires was not obtained without lowering the inflation pressure below that of a single tire of the same weight. A weight distribution of 60% of the total weight on the front wheel produced better performance for the tandem drive using equal size tires than did the weight distribution of 50% or 40% on the front wheel. The performance at a tire pressure of 6 psi was superior to that at 9 and 12 psi.