Abstract:
Ethiopia has a diversified agro-ecology, which makes the production of a wide range of cereal
crops possible. The major cereal crops are produced almost in all regions of the country though
there are variations in volume. Threshing is a key part of cereals processing that involves
removing the grains from crop plants, and from crop parts such as chaff, straw and stalk. In
Ethiopia, cereal crops are threshed by beating with sticks manually that require large amount
of hard labor accompanied with drudgery or by trampling under animal hooves. In this study,
a mechanical multi-cereal crops thresher was designed, manufactured and its performance is
evaluated. The performance parameters included threshing efficiency, cleaning efficiency,
mechanical damage, fuel consumption and throughput capacity at different feed rates and
cylinder speeds. Three levels of the cylinder speeds (350.00, 450.00, and 550.00 rpm), (750.00,
850.00 and 1000.00 rpm) and (850.00, 1000.00 and 1100.00 rpm) were used for threshing
maize, wheat and barley, respectively. Two levels of the feeding rates, 5.00 kg/min and 7.00
kg/min, were used for each cereal crop. Split plot design with three replications was employed.
The total number of experimental runs was 54. The results indicated that shelling/threshing and
cleaning efficiencies increased with increasing cylinder speed and decreasing feed rate.
Mechanical damage, fuel consumption and throughput capacity increased with increasing
cylinder speed and feed rate. The maximum threshing/shelling efficiency, cleaning efficiency,
mechanical grain damage, throughput capacity and fuel consumption were (99.56%,98.74 %
and 97.78%), (98.36%,95.51% and 94.95%), (2.01%, 0.19% and 0.24%), (209.73 kg/hr,201.61
kg/hr. and 199.41 kg/hr.) and (0.12L/qt.0.13L/qt and0.14L/qt) for maize, wheat and barley
respectively. The minimum threshing/shelling efficiency, cleaning efficiency, mechanical grain
damage, throughput capacity and fuel consumption were (96.34%, 95.17% and 94.14%),
(96.09%, 89.40% and 86.49%), (0.52%, 0.04% and 0.04%), (138.98 kg/hr,153.23 kg/hr. and
132.24 kg/hr.) and (0.09L/qt.0.09L/qt and 0.10L/qt) for maize, wheat and barley respectively.
Generally, the performance evaluation showed that the machine has performed satisfactorily.
