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Production Of Clean Grain From Multi Crop Thresher For Small Scale Farmers
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2.4 Factors Affecting Threshing
So many factors affect the threshing process some of which are
1. Cylinder speed: An optimum speed is desirable, excessive speed can cause the grain to crack and low speed can cause give unthreshed heads.
2. Cylinder concave clearance: The gap between the cylinder and the concave are usually adjustable. If the cylinder concave clearance is too small the power requirement will be high and also grain crack could increase while excessive clearance leads to unthreshed heads
3. Fan speed: Excessive fan speed can blow out the grain along with the chaff, whereas insufficient air flow can cause chocking of the sieves and unclean grains.
4. Sieve shaker speed:this influence the case of grain movement over the sieves. Most machines gave adjustment for each of the factors and the operation manuals should contains helpful advice about the correct speed to be used and machine specification suit the crop in the particular area. If the speed of the sieve shaker lead to unclean grain from the outlet while too small clearance lead to choking on the sieve. This particular significance in Nigeria where some of the threshers were imported from overseas (Meikle,2007).
2.5 Methods of Threshing
The method of threshing may be categorized into two forms which includes;Local method and Modern methods.
2.5.1 Local methods of threshing
Local method of threshing grains include: manual threshing of grain, threshing with animal or vehicle and threshing with hand driven machine
2.5.1.1 Manual threshing of grain
One of the simplest systems for threshing grain is to pick up the chaff of grain and strike or beat the panicles against the hard surface such as tub, threshing board or rack, or beating the chaffs spread out on the threshing floor with a flail or a stick or tramples it under foot. The threshing floors on which the chaffs are spread must have a hard clean surface. The pedal operated thresher consists of rotating drum with wire loops which strips the grains from panicles when fed by hand. It can be operated by women and can be used in hilly or terraced areas because its portability. By using one of these methods of hand threshing, a worker can obtained 15-40kg of product per hour. Source (Adewuyi 2009).
2.5.2.2 Threshing with animal or vehicles
If draught animals are available and there are large quantites of grain, threshing can done by driven the animals (harnessed in that case to threshing device) over a large of chaff about 30cm thick. This operation which also called “treading out†can be equally well be accomplished with vehicles. This method of threshing grains is adopted in some Asia countries, using a tractor to power instead of draught animals.Grains are obtained by running the tractor twice over chaffs of grain that are spread in layers on a circular threshing-floor 15-18m in diameter.(Adewuyi 2009).
2.5.2.3 Threshing with hand-driven machine
Machine driven by a manual devices or a pedal are often used to improved yield and working condition during threshing. By means of the handle or pedal, a big drum fitted with metal rings or teeth s made to rotate. The grain is threshed by hand holding the chaffs and pressing the panicle against the rotate drum. The speed of the threshing drum must be kept at about 300 revolutions per minute (rpm). The hand held chaff must all be of the same length with the panicles all laid in the same direction, and the grains must be very ripe and dry. Depending on the type of machine, the skill of the workers and organization of the work yield can be estimated at maximum of 100kg/h.Source (Adewuyi, 2009).
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ABSRACT - [ Total Page(s): 1 ]ABSTRACTThe 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 consider ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTS Title page Certification Dedication Acknowledgement Abstract Table of contents List of figures List of plates List of tables’ CHAPTER ONE: INTRODUCTION 1.1 Background of the study 1.2 Problem statement 1.3 Aims and objectives 1.4 Justification 1.5 Scope of the project CHAPTER TWO: LITERATURE REVIEW 2.1 Threshing Process ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONE INTRODUCTION1.1 Background of the StudyCowpea 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 ... Continue reading---
CHAPTER THREE - [ Total Page(s): 7 ]Torgue = F × rWhere, F = Centrifugal force =2666N R = radius of machine pulley 0.155 Torgue = F × r = 2666 × 0.155 = 413NmPower = Where,N = speed of the electric motor = 1430rpm = 3.142T = 413NmP = 2 × 3.142 × P = 61854.5KW3.4.3 Design for Shaft of the machine A shaft is a rotation machine element which is used to transmit power from one place to another. The power is delivered to the shaft by force and the resultant torgue ( ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 1 ]CHAPTER FOURRESULT AND DISCUSSION4.1 ResultThe experimental result obtained from the experiment is as shown in table 5.1 and 5.2 the raw data is as shown in appendix.4.2 DiscussionsA multi-crop threshing machine was modified and evaluated for performance. The threshing efficiency, unthreshed efficiency, breakage efficiency and throughput capacity were 90.1%, 9.5%, 20.1%, 143.4kg|hr for feed rate of 2kg and 90.9%, 9.1%, 14.11% and 251kg|hr for feed rate of 3kg respectively at a consta ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVECONCLUSION AND RECOMMENDATION5.1 Conclusion The following conclusion was drawn from the performance carried out on the multi-crop thresher.I. The speed of the blower was obtained which reduces the blown out of grains from the outletII. The feed rate of 3kg favors the constant speed of 300rpmIII. The higher the feed rates at the threshing drum the higher the throughput capacity.5.2 RecommendationBased on the result and conclusion, the foll ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCESAbdulkadir.B.H. and Olufemi A.O (2009).The design and construction of threshing machine.Assumption university journal of technology 12(3) pp199-206.Adaokoma (2001) Design and fabrication of multi-purpose grain dehauler.Eng Thesis, Department of mechanical engineering federal university technology (FUT) minna Nigeria.Adewumi (2006).Design, fabrication and preliminary testing of a thresher cleaner for grain legume, food science technology.Bates.W.N. (1999).Mechanization of tropical crops ... Continue reading---
