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Problem solving is a part of living. We are faced with a host of problems on a daily basis. Some of these problems involve people and human relations, whereas others require a mathematical solution. In this chapter we will deal with problems involving mathematical solutions, and several ways in which these problems can be approached.

There is no substitute for a good understanding of numbers and mathematical processes in solving modern agricultural problems. In this unit, we will discuss several features of numbers and techniques to use with numbers.

All measurements require a unit to define the precision of the measurement. The preferred unit depends on the magnitude of the measured variable. For example in the customary system, commonly used in the United States, when the distance is large the mile is the preferred unit. When the distance is very small the unit of measure could be in decimal inches (0.01 in) or fractions of an inch (3/64 in). The units of measure can be divided into several categories. The common categories used in agriculture are:

A machine is any device that either increases or regulates the effect of a force or produces motion. All agricultural machines are composed of combinations and modifications of two basic machines, the lever and the inclined plane. We will study the basic principles surrounding these two machines and illustrate some of their common modifications and uses. ( Note : In the following discussion of simple machines two assumptions are made: losses due to friction are ignored, and the strength of the materials is not considered.)

There are six primary sources of power in agriculture: human labor, domestic animals, wind, flowing water, electricity, and heat engines. The primary sources of power for modern agriculture are the internal combustion engine and electric motor. Some day, the primary source of power may change to fuel cells, solar energy, or atomic energy, but in the immediate future the primary sources of power for agriculture will continue to be internal combustion heat engines and electric motors.

In some applications, such as a push lawn mower with a vertical crankshaft engine, the power is used at the location that it is produced. The blade is attached directly to the end of the crankshaft. Most machines require a more complex system for transporting the power from the source to the load. In addition, many machines require that the power produced by the motor or engine be modified and/or transported to another part of the machine. These modifications could include changing the speed of rotation, direction of rotation, and location of the power. The collection of machine components that are used to accomplish this are called the transmission, power train, or drive train. In complex agricultural machines, such as a combine, the power must also be modified several times to meet the needs of the different machine components.

Tractors are very versatile machines, but the range of uses is too wide for one machine to be successful in all of the possible jobs. Tractor manufacturers target tractor designs for different categories of use. These category boundaries are not ridged, but if owner/operators push the boundaries too far, the tractor can fail which may lead to an accident which damages the tractor or implements. It can also result in injuries for the operator or bystander. It is important, therefore, for the owner/operator to have a basic understanding of the common categories of tractors. This chapter will also explain how stationary engines and tractors are derated, and how tractors are tested.

One role of agricultural machines is the dispensing of materials such as seeds, fertilizers, and sprays. These machines are designed to dispense the material at a fixed, or variable rate, and in a fixed, or variable pattern. A machine that fails to dispense the material at the desired rate and pattern should not be used. An insufficient amount of material will not produce the desired results, and excessive amounts are a lost resource that may result in crop damage and/or contribute to contamination of the environment.Apattern that is not correct may cause streaking or skips. Calibration charts or tables are usually supplied with or are available from the manufacturers of the machines in the owner’s manuals or from the supplier of the material being dispensed. Charts and tables become lost or damaged, leaving the operator with no or incomplete information.

To be efficient means being able to produce the desired results with a minimum of effort, resources, or waste. This is a concept that permeates our lives. A part of every occupation is the desire to improve the product or services by producing more for less or a better product for the same input. Engineers are constantly trying to improve the efficiency of operations by reducing the energy requirements and/or wastes from agricultural and manufacturing processes. When referring to machinery, efficiency is an evaluation of how well a machine does the tasks that it is designed to perform.

Machinery is one of the largest investments for agricultural enterprises. The selection process may include manufacturer, design, size, and options. A bad decision on any one of these factors will have a serious effect on the profitability of the enterprise. After studying this chapter, you should have a better understanding of the criteria to use when selecting tractors and machines, and be able to match tractor and machine sizes.