![]() ![]() This resistance of flow will result in pressure drops throughout the system, sluggish operation of the equipment, and an increase in power consumption. On the other hand, if the liquid is too thick (viscosity too high), the internal friction of the liquid will cause an increase in the liquid's flow resistance through clearances of closely fitted parts, lines, and internal passages. A liquid that is too thin will also allow rapid wearing of moving parts, or of parts that operate under heavy loads. Leakage losses are greater with thinner liquids (low viscosity). Any internal leakage through these clearances results in loss of pressure, instantaneous control, and pump efficiency. These components depend on close fits for creating and maintaining pressure. The viscosity of a liquid increases as the pressure on the liquid increases.Ī satisfactory liquid for a hydraulic system must be thick enough to give a good seal at pumps, motors, valves, and so on. That is, a liquid flows more easily when it is hot than when it is cold. As the temperature of a liquid increases, its viscosity decreases. The viscosity of a liquid is affected by changes in temperature and pressure. A liquid that flows easily, such as gasoline, has a low viscosity and a liquid that flows slowly, such as tar, has a high viscosity. It is a measure of a fluid's resistance to flow. ![]() Viscosity is one of the most important properties of hydraulic fluids. The most important properties of hydraulic fluid and some of its characteristics are discussed in the following paragraphs. However, a satisfactory liquid for a particular system must possess a number of other properties. If fluidity (the physical property of a substance that enables it to flow) and incompressibility were the only properties required, any liquid not too thick might be used in a hydraulic system. Identify types, characteristics, and origin for various hydraulic system contaminants.ĭescribe the controls and checks for various hydraulic system contaminants. Recognize various types of hydraulic liquids and their particular characteristics and uses. Identify the characteristics of liquid that make it desirable for use in hydraulic systems.ĭescribe the properties and characteristics that must be considered in selecting a hydraulic liquid for a particular system, including related data. When you have completed this chapter, you will be able to do the following: ![]() Included in it are sections on the properties and characteristics desired of hydraulic fluids types of hydraulic fluids hazards and safety precautions for working with, handling, and disposing of hydraulic liquids types and control of contamination and sampling. This chapter is devoted to hydraulic fluids. Some of the factors include required speed and accuracy of operation, surrounding atmospheric conditions, economic conditions, availability of replacement fluid, required pressure level, operating temperature range, contamination possibilities, cost of transmission lines, limitations of the equipment, lubricity, safety to the operators, and expected service life of the equipment.Īfter the type of system has been selected, many of these same factors must be considered in selecting the fluid for the system. Graphic Symbols for Fluid Power Diagramsĭuring the design of equipment that requires fluid power, many factors are considered in selecting the type of system to be used - whether hydraulic, pneumatic, or a combination of the two.Reservoirs, Strainers, Filters, & Accumulators. ![]()
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