ABSTRACT

A motorized cowpea threshing machine was constructed in this project consists of shaped hopper inclined at an angle of 45  on the concave cover, sieves with 13 mm holes, shaft, bolt bearings, pulleys, thresh out let collecting through, V – belt and a straight bladed cleaning fan to provided the volume of air required. The machine is portable and operated by a 3.73 kw (5 hp) electric motor. It runs at a threshing cylinder Speed 500 rpm and the fan speed is 1400 rpm, it has a threshing efficiency of 84.9% capacity of threshing 10.5 kg in 3 minute 71 second and  the cleaning efficiency 28.6% breakage percentage of the cowpea is 4% the present cost of production of the machine is N 95,480.

CHAPTER ONE

1.0       INTRODUCTION

1.1       BACKGROUND OF THE STUDY

The cowpea plant, botanical known as vigna Unguiculata is a leguminous crop which originated from Central Africa from where it has been introduced to various other countries (John et al., 1976; Olatunde, 1974). Cowpea is a short-day, warm-weather crop grown under humid conditions. It is adapted to a wide range of soils, but thrives best under good drainage conditions. The pod size of cowpea at maturity varies. Its length can range from 150 mm to more than 300 mm depending on species (Onwueme and Sinha, 1991) and its diameter can range from 8 mm to 10 mm (Langer and Hill, 1982). The number of seeds per pod ranges from 8 to 20. The shape and color of seeds are also variable. They may be kidney-shaped or globular, smooth or wrinkled, and white, green, buff red, brown or black in various combination of mottled, speckled or blotched eyed (Langer and Hill, 1982).According to Langer and Hill (1982), cowpea is most important in Africa where over 95% of the world’s crop is grown, 61% in Nigeria alone. Most of the cowpea is grown for its edible seed (Onwueme, 1979). The dry seeds contain about 25% protein, 57% carbohydrate, 4% fiber and just over 1% fat (Langer and Hill, 1982). The immature pod comprises 86% water and

about 3.3% protein and 7.5% carbohydrates. Cowpea can be consumed in various forms. In Nigeria, the test is removed from the soaked seeds and the seeds ground into paste. This paste is then mixed with other ingredients and fried into little balls (Akara) or alternatively, the paste may be wrapped in leaves and cooked to make moin-moin. The green seeds and leaves are often eaten as vegetable (Mayhew and Penny, 1988).The importance of Cowpea lies in its food value as a major source of protein of high biological value, energy, vitamins and roughage. In addition, the crop is important as source of animal feed (Singh and Hymowitz, 1985). Cowpea is gaining popularity and has several other advantages over other food crops. The reason being its edible forms available, such as tender green shoots, leaves, unripe whole pods, green peas or beans and dry seeds. Cowpea forms a major component of low land cropping system. This is because it provides its own nitrogen requirements through symbiotic nitrogen fixing bacteria (Rhizobia) and leaves generous amount of nitrogen for a subsequent crop. This is of interest especially in this period of rising fertilizer prices (Parman, 1974). With the growing demand for protein rich food in developing countries, attention has been focused on cowpea production whose protein ranges from 30-45% (Bates, 1963) besides Calcium, Phosphorus, and Vitamin B.

In Nigeria hand tools were the only means used in carrying out all forms of farming operations for centuries. This called for high labour input and low output. But due to the rapid increase in population and the need to produce enough food to cater for the growing population, the country is now involved in all forms of mechanized farming practices. Mechanization reduces human labour and drudgery and increase yield per hectare of each cultivated land. To do this, different types of machines have to be fully employed to achieve such practices like land clearing, planting, harvesting and threshing. After grains are harvested, threshing needs to be carried out. Farmers often find insufficient threshing a post-harvest operation that involved the removal of the grain from the cob, or detaching grains from the pods of crops with or without cleaning or separating. In other words, it is the process of removing or separating of grains or seeds from the crop pods or straw. The machine involved in carrying out this operation is known as “Thresher” (Kaul and Egbo 1985). In developing countries like Nigeria, most threshing of cereals like sorghum, millet, cowpea and wheat is carried out manually by beating with sticks. Apart form the high labour requirement, this is a very ardous task. In addition the grains become contaminated with dirts from contact with the ground where the beating is done and major loss is encountered during the process. As a result of the aforementioned problems, it has become imperative to come up with solution that will help in alleviating the farmer problems. A motorized cowpea thresher that would be capable of threshing, separating and cleaning the crop is intended to be constructed.The cowpea thresher is to be constructed using locally available quality materials. The machine should be relatively cheaper than the imported ones so as to make it affordable to farmers.

1.2       STATEMENT OF THE PROBLEM

Fatigue is involved in threshing, which indirectly discourage people getting involved in agricultural production, manual threshing is time consuming and affects output and quality of crops, as cowpea is a source of protein, there is always the need to increase output which also result in more labour requirement for threshing, the prices for the thresher being imported are far beyond the reach of a present farmers.

1.3       AIM & OBJECTIVES

The aim of the project is to construct a cowpea threshing machining with the following objectives

i.          To prepared preliminary design of the machine

ii.         To construct the machine

iii.        To test the machine

1.4       SIGNIFICANCE OF THE PROJECT

Threshing is one of the major components involved in processing of cowpea. The cowpea available in the market now is always filled with stones and foreign Materials which tends to affects it quality and marketability, availability and affordable locally Produced Thresher will make the availability of clean seed easier then if is none and will make the threshing of cowpea less difficult and more attractive to farmers. They will generally lead to improve cowpea production.

1.5       SCOPE OF THE PROJECT

This Project work involves some preliminary design work taking into consideration. The power Source, the thresher will be produced with locally available materials as much as possible. Preliminary testing of the thresher will be carried out.

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