Performance evaluation of a multi crops thresher

Abstract

Legume crops are the most cultivated grasses for their edible seeds, that is, 2500 million tons in the world, unlike any other type of crop. However, the threshing of these cereals remains a big challenge. Most motorized threshers are adapted to a single crop making the uneconomical for our mixed cropping system in Uganda, there was thus the need to evaluate the performance of multi crops threshers to solve the above-mentioned problem by recommending suitable parameters like moisture content for which different crops can be optimally threshed. Therefore, the main objective of this study was to assess the performance of a multi crops thresher fabricated by DABE at MUARIK. The main components of the prototype are the feed hopper, concave drum, motor, fan, and pulley system. The evaluation was carried out by threshing soybean, sorghum, and millet crops at different moisture contents with at least three replications for each. The oven-drying method was used to test for the moisture content of the grains. The moisture content tested for soybean was 20.2, 18.4, 15.3, 13.5, and 12.6%, and for sorghum grains 18, 15.4, 13.7%, and 12.55% for millet. Grain damage percentage, threshing and cleaning efficiency, and throughput capacity were measured for the different types of grains at different moisture contents. Statistical analysis was made by using SPSS statistical software analysis function for the significance of the results and recommendations for optimum moisture content for threshing each crop were made. The machine performed best as follows; the average capacity of the machine for sorghum, soybean, and millet was found to be 704.66 kg/ hr at, 74.3 kg/ hr and 591 kg/hr, with average threshing efficiencies of 94.58%, 98.4%, 89.1%, average cleaning efficiencies of 93.78%, 95.8% and 76.3% for sorghum, soybean, and millet respectively. The average grain damage was also 0.35%, 2.0%, and 2.6% for the respective crops. Generally, machine capacity, cleaning, and threshing efficiencies increased with a decrease in moisture content while the percentage of damage decreased with decreasing moisture content. Increasing the distance between the different outlets to prevent mixings and adding a third wheel for easy movement are some of the suggested improvements to make on the machine.