ABSTRACT
The traditional methods of threshing of crops are inefficient, laborious, and time consuming and low out put. The existing fabricated machine was observed during preliminary testing to have low performance. In the light of the above mentioned problems, there is need to modify and testing multi-crop thresher to threshed grain at optimum speed. The threshing machine consist of the following component: Hopper, frame, beater, sieve, pulley, grain outlet and chaff outlet. The factors considered in this project work was feed rate at two levels of 2 level and were replicated twice (f1=2kg, f2=3kg) at a constant speed of 300rpm. The parameters under investigation were threshing efficiency, unthreshed efficiency, and breakage efficiency. The result revealed that the machine has a threshing efficiency, unthreshed efficiency, and breakage efficiency of 90.1%, 9.5%, and 20.1% for feed rate 2kg and 90.9%, 9.1% and 14.11% for feed rate 3kg respectively. The time taken for 2kg and 3kg was 50.2sec and 43sec, the throughput capacity for 2kg was 143kg|hr and 3kg was 167kg|hr respectively. The feed rate of 3kg favors the machine performance.
CHAPTER ONE
 INTRODUCTION
- Background of the Study
Cowpea is a grain legumes appears to have originated from west-African, very widely in Nigeria were there are many wild weedy species in both savanna and forest zone (Steel, 1992). Cowpeas are now widely distributed throughout the tropics and sub-tropics. They are grown in India, south eastern Asia, and Australia the Caribbean, southern united state and throughout the low land tropical Africa. Nigeria alone produces 61% (760000 tones) of the world total production (Irtwange 2009). Despite this figures, Nigeria continues to suffer from hunger and malnutrition. This is because the rate that of population growth is exceeded the rate of food production with a consequent decline in per capital food intake (Irtwange 2009). This call for the need to step up food production.
Grain, according to Okaka (2004) is fruit of cultivated grasses belonging to the family of monocotyledonous, gramineace. The principle cereal grain of the world includes wheat, beans, sorghum, rice and maize. Agriculture commodities are consumed as food and grains contributed to the bulk of the country’s calories and protein. The world grain is broadly used to indicate cereals and pulses. Grain however can be grown extensively for food and the fast growing agricultural based industries. They are used in either fresh form or dried form. Dried grains are preferred for industrial uses. The major processing methods used in preparing grain are dry milling wet milling and malting (Olatunji,2000).
Maize (zeamays) is cereal crops that are grown widely throughout the world in a range of agro ecological environments more maize is produced annually than any other grains. About 50 species exist and consist of different colors, texture and grain shapes and seize, white yellow and red are most common types. The white and yellow varieties are preferred by most people depending on the region maize was introduced into Africa the 1500s and since become one of African dominant food crop. The grains are rich in vitamin A, C, and E carbohydrates and essential minerals and contain 99% protein. They are also rich in dietary fiber and calories which are good source of energy (Adeokoma2001).
The major steps involves in the processing of maize are harvesting, drying, de-husking, shelling, storage and milling. For rural framers to maximize profit from the maize, appropriate technology that suites thresher need must be used. The processing of the agricultural product like maize into quality form not only prolong the sheff life of these product but also increase the net profit the farmer make from mechanization technology of such product.(okaka 2004). Guinea corn (sorghum) is a cereal grain that originated in Africa and is eaten throughout the world. It is especially valuable in arid terrain because of its resistance to drought, guinea corn is a nutrient rich grain that is often grand into flour to make bread, porridge and pancake including it diet offers a number of nutritional and the rapeutic benefit guinea corn contain 163 calories protein, carbohydrate, fat content minerals, the one nutritional highlight of guinea corn is its mineral content. Adequate intake of iron support the transportation of oxygen in the body system and helps to promote cell growth and development of potassium helps to maintain fluid balance, and high intake in food blood pressure according to American heart association (Purseglove, 2007).
1.2 Problem Statement
Traditional threshing method do not support large- scale threshing of grains especially for commercial purposes. Locally in Nigeria the region that is the highest producer of grain like maize is the northern part of the country it was observed that the most threshing of grain was done by hand shelling. Hand threshing take a lot of time, even with some hand operated simple tools, it was also observed in the study area, most mechanical threshers were designed for multi grain threshing or shelling, which causes great damage to the grain seed besides breaking the maize cob to pieces the available Sheller were locally equipped with rotating threshing drum with beater or teeth which cause damages to the seed. Besides, the costs of purchasing such thresher were high for poor rural farmer and therefore necessitated the design of low cost system that will be affordable and also increases threshing efficiency but reduce damage done to the seed (Ogunwede,2003).
