This book has been written to meet the requirement of students getting knowledge in Agricultural Engineering and Farm Machinery and Power Engineering. This book is prepared by keeping the ARS-NET syllabus of Farm Power and Machinery discipline in mind and it contains excellent collection of important points on farm machinery, farm power, ergonomics, theory of machines, energy in agriculture, instrumentation and workshop technology to meet requirements of students. The book serve as a useful resource to the agricultural engineering and farm machinery and power engineering students appearing for various competitive exams such as ICAR JRF/SRF, NET,ARS and GATE etc. The book contains a section on key notes related to important terms on farm machinery and power engineering. It is useful for better understanding of this subject.
Preface This book has been written to meet the requirement of students getting knowledge in Agricultural Engineering and Farm Machinery and Power Engineering. A need has felt for a book on this subject of basic standards. A keen attempt has been made to make the book useful and interesting. Leaving all the unnecessary things only the essential facts and concepts have been discussed in this book. It has a direct link with all the concepts in the farm machinery and power engineering that all the common and complicated concepts have been explained very short and clearly. It has been experienced that many students lack in their confidence to face examinations, therefore this book has been written in such way that it may equip the students with basic knowledge to face examinations. This book is prepared by keeping the ARS-NET syllabus of Farm Power and Machinery discipline in mind and it contains excellent collection of important points on farm machinery, farm power, ergonomics, theory of machines, energy in agriculture, instrumentation and workshop technology tomeet requirements of students. The book should serve as a useful resource to the agricultural engineering and farm machinery and power engineering students appearing for various competitive exams such as ICAR JRF/SRF, NET,ARS and GATE etc. The book contains a section on key notes related to important terms on farm machinery and power engineering. It is useful for better understanding of this subject. The authors are deeply thankful to individuals, who helped on time for preparing this book. It is hoped that this book will be useful for all the students of agricultural engineering as well as farm machinery and power engineering. Any suggestions towards its further improvement will be thankfully acknowledged and incorporated in the next edition.
Agricultural mechanization involves the design, manufacture, distribution, use and servicing of all types of agricultural tools, equipment and machines. It includes three main power sources: human, animal and mechanical with special emphasis on mechanical (tractive power). Mechanization has been identified as one of the critical inputs for production agriculture. It may be described as an appropriate package of technology to i) ensure timely field operations to increase productivity, reduce crop losses and improve product quality, ii) increase land utilization and input use efficiency and iii) increase labour productivity through labour saving and drudgery reducing mechanical devices. The mechanization of Indian agriculture has proceeded along two-pronged approach based on improved equipment and enhanced power supply. However, compared to the mechanization of western agriculture which was motivated by the need to substitute human labour and draught animals with mechanical prime movers, the guiding principle in mechanizing Indian agriculture has been to maintain a socially desirable mix of human labour, draught animal power and mechanical power.
Classification of Materials Broadly there are two groups of materials used for making farm machines namely metallic and non-metallic:
It is a mechanical manipulation of soil to provide favourable condition for crop production. Soil tillage consists of breaking the compact surface of earth to a certain depth and to loosen the soil mass, so as to enable the roots of the crops to penetrate and spread into the soil. Tillage operations following primary tillage which are performed to create proper soil tilth for seeding and planting are secondary tillage. These are lighter and finer operations, performed on the soil after primary tillage operations. Secondary tillage consists of conditioning the soil to meet the different tillage objectives of the farm. These operations consume less power per unit area compared to primary tillage operations. Secondary tillage implements may be tractor drawn or bullock drawn implements.
Seeding or sowing is an art of placing seeds in the soil to have good germination in the field. A perfect seeding gives a) Correct amount of seed per unit area. b) Correct depth at which seed is placed in the soil. c) Correct spacing between row-to-row and plant-to-plant. Seed drill is a machine for placing the seeds in a continuous flow in furrows at uniform rate and at controlled depth with or without the arrangement of covering them with soil. Planter is normally used for those seeds which are larger in size and cannot be used by usual seed drills. A planter consists of: (i) hopper (ii) feed metering device (iii) knock out arrangement (iv) cut-off mechanism (v) furrow opener and (vi) other accessories. A planter has seed hopper for each row.
Sprayer is a machine to apply fluids in the form of droplets. Sprayer is used for the following purpose. Application of herbicides to remove weeds. Application of fungicides to minimize fungus diseases. Application of insecticides to control insect pests. Application of micro nutrients on the plants.
It is the operation of cutting, picking, plucking and digging or a combination of these operations for removing the crop from under the ground or above the ground or removing the useful part or fruits from plants. Thresher is a machine to separate grains from the harvested crop and provide clean grain without much loss and damage. During threshing, grain loss in terms of broken grain, un-threshed grain, blown grain, spilled grain etc. should be minimum. Bureau of Indian Standards has specified that the total grain loss should not be more than 5 per cent, in which broken grain should be less than 2 per cent. Clean un-bruised grain fetch good price in the market as well as it has long storage life. It is a machine designed for harvesting, threshing, separating, cleaning and collecting grains while moving through standing crops. Bagging arrangement may be provided with a pick up attachment. The main functions of a combine are: (i) Cutting the standing crops (ii) Feeding the cut crops to threshing unit (iii) Threshing the crops (iv) Cleaning the grains from straw (v) collecting the grains in a container.
A machine is a device which receives some sort of energy and does some work. A rigid link is one, which does not undergo any deformation while transmitting motion. A flexible link is one which is partly deformed in a manner not to affect the transmission of motion. A structure is an assemblage of a number of resistant bodies having no relative motion between them. A turning pair has a completely constrained motion. Cam and follower includes higher pair. The lower pairs are self-closed pair.
Tractor is a self-propelled power unit having wheels or tracks for operating agricultural implements and machines including trailers. Tractor engine is used as a prime mover for active tools and stationary farm machinery through power take-off shaft (PTO) or belt pulley. Power tiller is a prime mover in which the direction of travel and its control for field operation is performed by the operator walking behind it. It is also known as hand tractor or walking type tractor. The concept of power tiller came in the world in the year 1920. Japan is the first country to use power tiller on large scale. Power tiller was first introduced in India in the year 1963. Power tiller is a walking type tractor. The operator walks behind the power tiller, holding the two handles of power tiller in his own hands. Power tiller may be called a single axle walking type tractor, though a riding seat is provided in certain designs. In agricultural applications it is often required to transmit the mechanical power from its source to the point of application. The main sources of power for agricultural machines, i.e., the diesel engine for self-propelled machines and the electrical motor for many stationary machines are primarily rotary power and are transmitted by means of belts and chains. Tractor power is utilized by traction, power-take-off drives (PTO) by fluid power.
Ergonomics (also known as Human Engineering, Human Factors or Human Ergology) is the scientific study of relationship between a person and his/her working environment. The term environment includes the tools, materials and method of work, ambient conditions and physical environment in which the work is carried out, and also the organizational factors. Ergonomics application can help in increasing the efficiency and productivity, reducing drudgery and occupational health problems, and enhancing safety of workers in various activities.
Energy is defined as the capacity of doing work and is necessary for survival. It is basic input to any society’s development and economic growth. Everything happens in the world is the expression of flow of energy from one form to other. There are different sources of energy, i.e., chemical, mechanical, fossil, nuclear and renewable energy. The following products are obtained from refining of crude oil
For development of agricultural engineering machineries, materials and manufacturing techniques play a very important role. Functionality, efficacy, life span, economics and aesthetic of any machine or structure are affected severely by the material of fabrication process. The manufacturing processes discussed in this chapter also include the pretreatment to manufacturing and structural materials. Wood and some kind of ferrous alloys had been the choice of materials for fabrication of agricultural machines in past few centuries, whereas these materials along with mud, bamboo, some agricultural residues and some earthen materials were the materials of choice for agricultural structures. Engineering materials are available with wide range of properties and characteristics. There are many properties, which are inherent in the materials, and some of them can be changed during processing and manufacturing.
Measurement also forms a basic element of any control process. The measurement of discrepancy between the actual and desired performance of a system is central to any control process. Electronic instrumentation provides the solution to many and varied problems of measurement and control. It is often required to change or transduce a measurand into a corresponding electrical signal. The elements which changes/converts the physical variable in electrical signal are termed as sensors or transducers. For a measurement to be useful it must be reliable. That is where question of accuracy or uncertainty of a measurement arises. This may be dealt with clear understanding of measurand and measurement system.
Spray Angle — The angle subtended at the final orifice by the edges of the spray pattern. Variation in discharge rate between first and last observation shall not be more than 5 percent. The volumetric efficiency requirement for roller vane type pump shall be minimum 80 percent. The volumetric efficiency of piston, plunger type pump shall be minimum 80 percent. If the droplet size is reduced from 2 mm to 1 mm, number of droplets produced will increase by 8 times from the same volume.
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