Abstract:
Production activities including harvesting and post-harvest handling of the common beans
need great attention to ensure the abundance of the product both in quality and quantity for
enhancing food security and income generation. Threshing is one of the post-harvest activities
and the traditional threshing method is crude, labor intensive, tedious and time-consuming,
and grossly inefficient. In this study, a common bean thresher was designed, developed and
tested for its performance. The performance parameters included threshing efficiency,
cleaning efficiency, mechanical damage, and throughput capacity at different feed rates and
drum speeds. Three levels of the feed rate (120, 140, and 160 kg/hr) and three levels of the
drum speed (350, 450, and 550 rpm) were tested under factorial in split-split plot with every
trial replicated thrice making a total number of the experimental runs to be 27. Results
showed that threshing efficiency and cleaning efficiency increased with increasing drum speed
and decreasing feed rate. Mechanical damage and throughput capacity increased with
increasing drum speed and feed rate. Maximum threshing efficiency of 99.77 % and maximum
cleaning efficiency of 84.48 % were obtained at a drum speed of 550 rpm and feed rate of 120
kg/hr. A maximum throughput capacity of 60 kg/hr was obtained at a drum speed of 550 rpm
and a feed rate 160 kg/hr. Results also showed that throughput capacity increased with the
increasing speed of the screw conveyor in the anti-chocking unit. Generally, the data obtained
from the performance evaluation showed that the machine has performed satisfactorily
