Abstract
The economic situation in most developing countries have left farmers and processors operating at the small scale, hence the use of automated and electric power driven equipment is limited to the few large scale processors. The effect of the ergonomic parameters namely; weight, age, height and arm length in relation to the resulting efficiencies; shelling efficiency, cleaning efficiency, mechanical damage and percentage sieve loss of a hand powered Maize Sheller incorporating a blower were studied using a non linear regression analysis. The study was with a view to developing a model for the performance of the hand powered maize sheller. The power transmission increases the speed of the blower for high cleaning efficiency. Preliminary studies were carried out to determine the ergonomic data of operator, and moisture content and grain/chaff. The results on studies with maize with 12% dry basis moisture content and grain/chaff ratio of 3.04:1 show that weight has the most significant effect (p<0.05). The mean of the shelling efficiency, cleaning efficiency, sieve loss and mechanical damage of the machine are 94.3, 96.4, 2.3 and 5.23% respectively and the coefficient of determination for the regression equations relating the ergonomic parameters to machine efficiency and parameters ranges from 0.29 to 0.86 with quadratic regression obtained. Equations were derived to relate the variables and an approximate solution was obtained from a particular example, which validates the theoretical prediction with known results. Key words: Shelling, efficiency, hand powered, ergonomic, model.
Highlights
Maize (Zea mays) is one of the most common cereal crop grown in the world
Maize shelling is difficult at a moisture level content above 25%, with this moisture content, grain stripping efficiency is very poor with high operational energy and causing mechanical damage to the seed
It was observed that the height (H), arm length (AL) and weight (W) of operators increase with increase in age
Summary
Maize (Zea mays) is one of the most common cereal crop grown in the world. The period between planting and harvesting for maize depend upon the variety, but in general the crop physiologically mature 7 to 8 weeks after flowering at that time the kernel contains 35 to 40% moisture and has the maximum content of dry matter (Danilo, 1991). Shelling is the removal or separation of maize grain from the cob and it is an operation that follows the harvest. It can be carried out in the field or on the farm by hand or with the help of animals or machines. A more efficient shelling is achieved when the grain has been suitably dry to 13 to 14% moisture content (Danilo, 1991)
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