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Chapter One Introduction to Fluid Power What is fluid power? • Technology, which deals with the generation, transmission, and control of power using, pressurized fluids • Hydraulics refer to the use of liquids, primarily some type oil • Pneumatics refer to the use of gases, the most popular is air (it is cheap) Types of Fluid Systems • Fluid Transport – Sole purpose is to move fluid from one location to another • Fluid Power – Like transport systems, power systems move fluid but are designed to perform work – The fluid is bears upon cylinders and motors ( actuators) to accomplish the work Advantages of Fluid Power • • • • Ease and accuracy of control Multiplication of force Constant force Economical (fewer parts) Disadvantages • • • • Messy Noisy Potentially explosive Leaks – (No such thing as leak free hose connections) Basic Components: Hydraulic • • • • • • • Reservoir Pump Prime Mover Valves Piping Actuators Filter Basic Components: Pneumatic • • • • • • • Compressed Air tank Compressor Prime Mover Valves Piping Actuators Filter Fluid Power Controls • Electrical • PLC • Closed/Open loop How does the system work? • Pascal’s Law The pressure exerted on a confined fluid is transmitted in all directions and acts at right angles to the containing surfaces. • (F = P x A) – P = pressure (psi or kPa) – A = area (in2 or m2) Applications of Pascal’s Law • The most common uses of Pascal’s law are multiplicity and continuity F1 F2 A1 A2 Applications of Pascal’s Law • Additionally, we can draw relationships with distance since the volume of the system will be constant F2 S1 A2 F1 S 2 A1 Common Variables Variable SI Force Newtons (kg-m/sec2) Pressure Pascal (N/m2) Area Meters2 Time Seconds Velocity M/sec Length Centimeters/Meters Volume M3 Acceleration M/sec2 English Lbf Lbf/in2 Inches2 Hrs Ft/sec Inches/Feet In3 Ft/ sec2 review of important terms and definitions that are often used in hydraulics • Mass The mass of a body or an object is a measure of the quantity of matter contained in it. • Volume: The space occupied by a body is called its volume. • Density: The density of a substance is defined as its mass per unit volume. • The relative density of a substance is the ratio of its density to the density of some standard substance. • Velocity:The distance covered by a body in a unit time interval and in a specified direction. • Acceleration which may be defined as the rate of change of velocity of a moving body. • The force is an attempt of either changing the position/displacement of the object or its dimensions. • Weight: Weight refers to the force of gravity acting on a given mass. • specific weight or weight density of a fluid is defined as the ratio of the weight of the fluid to its volume. • Work is defined as force through distance. Work (W) = Force (F) x Distance moved or displacement (s) • Energy: A body is said to possess energy when it is capable of doing work. forms of energy: • Potential energy (PE) • Kinetic energy (KE) • Internal energy • Power: The rate of doing work Power (P) = Work done (W)/ Time (t) Power = Force x Average velocity OR P = F * v • Horsepower: is the power of one horse • 1 hp = 746 W