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.