PROOF-OF-CONCEPT EVALUATION OF A LOW-COST AND LOW-WEIGHT TRACTOR FOR SMALL-SCALE FARMS

About 80% of farms in India are less than five acres in size and are cultivated by farmers who use bullocks for farming operations. Even the smallest tractors available in the Indian market are too expensive and large, and not designed to meet the unique requirements of these farmers. To address these needs, we have developed a proof-of-concept lightweight (350 kg) tractor in collaboration with Mahindra and Mahindra Limited, an Indian tractor manufacturer. Given the challenges of accurately predicting traction in Indian soils by applying existing terramechanics models, an alternative design approach based on Mohr-Coulomb soil-failure criterion is presented. Analysis of weight, power and drawbar of existing tractors on the market, a single wheel fraction test, and a drawbar test of a proof-of-concept small tractor prototype suggest that similar to 200 kg is the maximum drawbar force that could be achieved by a 350kg tractor of conventional design. In order to attain higher drawbar performance of 70% of the tractor weight needed for specific agricultural operations, additional design changes are required. An approach for increasing traction by adding tires is investigated and discussed. Additional research on weight distribution, dynamic drawbar testing and tread design is suggested as future work.