Development and Performance Evaluation of a Spring-Loaded Hand Operated Maize Sheller with Variable Mechanisms

Abstract

A spring-press, variable mechanism hand operated maize sheller was developed, constructed and tested with corn cobs at 12.6% moisture content, wet basis (w.b) and its shelling performances compared. The machine is lever operated with a spring load-return mechanism and a cob constrictor with changeable shelling mechanisms (spike tooth, rasp bar and star tooth), and a tilted tray for grain collection. The overall dimension of the machine is 520mm x 520mm x 400mm. The machine overall performance is 20.62kg/hr shelling capacity, 85.13% shelling efficiency and 2.13% kernel damage. Comparing the performance of the three shelling mechanisms; rasp bar, spike tooth and star tooth, shelling capacity (16.2, 26.0, 19.67) kg/hr.; shelling efficiency (82.22%, 87.19%, 85.97%); and % kernel damage (0.00, 0.74, 0.51) respectively, the star mechanism has a higher capacity of 26.0kg/hr. The mean kernel damage is higher for star tooth, whereas it is zero for rasp bar. In comparison with conventional hand-palm shelling method (100% shelling efficiency, 13.83kg/hr shelling capacity and 0% kernel damage), the hand operated sheller has a better output capacity, reasonable shelling efficiency but slightly higher kernel damage. By implication, machine performance efficiency does not give a true reflection of how effective a system work until the machine capacity is determined. The sheller ease household shelling maize for consumption with initial low production cost of N13, 100.00 (~$30).