Lesson 3.3 Fluid Power



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|Lesson 3.2 Fluid Power |

Concepts

1. Fluid power systems are categorized as either pneumatic, which utilizes gas, or hydraulic, which utilizes liquid.

2. Fluid power is possible because in a system of confined fluid, pressure acts equally in all directions.

3. The most basic components of all fluid power systems include a reservoir or receiver, a pump or compressor, a valve, and a cylinder.

4. Fluid power systems are designed to transmit force over great distances, multiply an input force, and increase the distance that an output will move.

5. Laws about the behavior of fluid systems and standard conventions for calculating values within fluid systems aid in the design and understanding of such systems.

6. Standard schematic symbols and conventions are used to communicate fluid power designs.

Performance Objectives

It is expected that students will:

• Identify devices that utilize fluid power.

• Identify and explain basic components and functions of fluid power devices.

• Differentiate between the characteristics of pneumatic and hydraulic systems.

• Distinguish between hydrodynamic and hydrostatic systems.

• Design, create, and test a hydraulic device.

• Design, create, and test a pneumatic device.

• Calculate values in a fluid power system utilizing Pascal’s Law.

• Distinguish between pressure and absolute pressure.

• Distinguish between temperature and absolute temperature.

• Calculate values in a pneumatic system utilizing the perfect gas laws.

• Calculate flow rate, flow velocity, and mechanical advantage in a hydraulic system.

Essential Questions

1. What impact does fluid power have on our everyday lives?

2. Can you identify devices or systems that do not use fluid power that might be improved with the use of fluid power?

3. What are similarities and differences of mechanical advantage in simple machines and hydraulic systems?

4. Why are Pascal’s Law, the perfect gas laws, Bernoulli’s Principle, and other similar rules important to engineers and designers of fluid power systems?

Key Terms

|Absolute Pressure |The total pressure exerted on a system, including atmospheric pressure. |

|Atmospheric Pressure |The pressure exerted by the weight of the atmosphere above the point of measurement. |

|Boyle’s Law |The volume of a gas at constant temperature varies inversely with the pressure exerted on it. |

|Charles’ Law |States that the volume of a confined gas is proportional to its temperature, provided its pressure |

| |remains constant. |

|Check Valve |A valve that allows flow in one direction but prevents flow in the opposite direction. |

|Compressor |An air pump that compresses air into a receiver tank. |

|Crank |A part of an axle or shaft bent out at right angles, for converting reciprocal to circular motion |

| |and vice versa. |

|Cylinder |A device used to convert fluid power into mechanical power in the form of linear motion. |

|Directional-Control Valve |Used to control which path fluid takes in a circuit. |

|Double-Acting Cylinder |A cylinder that can act under pressure in both directions (extend and retract) to move a load. |

|Filter |A device used to remove contamination from a fluid. |

|Flow Meter |A device used to measure flow rate. |

|Flow Rate |The volume of fluid that moves through a system in a given period of time. |

|Flow Velocity |The distance the fluid travels through a system in a given period of time. |

|Flow-Control Valve |Used to start and stop flow in a circuit. |

|Fluid Power |The use of a fluid (liquid or gas) to transmit power from one location to another. |

|Gay-Lussac’s Law |The absolute pressure of a confined gas is proportional to its temperature, provided its volume |

| |stays constant. |

|Hydraulics |The use of a liquid flowing under pressure to transmit power from one location to another. |

|Lubricator |A device used to spray an oil mist into the stream of a pneumatic system. |

|Pascal’s Law |Pressure exerted by a confined fluid acts undiminished equally in all directions. |

|Piston |A sliding piece moved by or moving against fluid pressure which usually consists of a short |

| |cylindrical body fitting within a cylindrical chamber or vessel along which it moves back and forth.|

|Pneumatics |The use of gas flowing under pressure to transmit power from one location to another. |

|Pressure |The force per unit area exerted by a fluid against a surface. |

|Pressure Regulator |A type of pneumatic pressure control valve that controls the maximum pressure in a branch of a |

| |circuit. |

|Pressure Relief Valve |A type of pressure control valve that limits the maximum pressure in a hydraulic or pneumatic |

| |circuit. |

|Pump |A device used to create flow in a hydraulic system. |

|Receiver Tank |A device that holds the compressed air in a pneumatic system. |

|Reservoir |The tank that holds the fluid in a hydraulic system. |

|Single-Acting Cylinder |A cylinder that acts under pressure in one direction only and returns automatically when the |

| |pressure is released. |

|Solenoid |A switching device that uses the magnetic field generated by an electrical current for actuation. |

|Transmission Lines |Used to transport fluid in a circuit. |

|Valve |Any device that controls, either automatically or manually, the flow of a fluid. |

|Viscosity |A measure of a fluid’s thickness or resistance to flow. |

|Volume |The amount or quantity of something. |

Instructional Resources

Presentations

Pneumatic Power

Hydraulic Power

Fluid Power Introduction

Fluid Power Applications Exemplar

Word Documents

3.2.1 Fluid Power Applications

Activity 3.2.2 Pneumatic Demonstration

Project 3.2.3 Pneumatic Brake Design

Example Pneumatic Compressor Design

Activity 3.2.4 Hydraulic Demonstration

Project 3.2.5 Hydraulic Lift Design

fischertechnik® Pneumatic Components

Fluid Power Practice Problems

Lesson 3.2 Key Terms Crossword

Reference Sources

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Hooper, J.F. (2003). Basic pneumatics: An introduction to industrial compressed air systems and components. Durham, NC: Carolina Academic Press.

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International Technology Education Association. (2000). Standards for technological literacy. Reston, VA: ITEA.

Johnson, J.L. (2002). Introduction to fluid power. United States: Thomson Learning, Inc.

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National Council of Teachers of Mathematics (NCTM). (2000). Principles and standards for school mathematics. Reston, VA: Author.

National Fluid Power Association & Fluid Power Distributors Association. (n.d.). Fluid power: The active partner in motion control technology. [Brochure]. Milwaukee, WI: Author.

National Fluid Power Association. (2008). Retrieved February 15, 2008, from

National Research Council (NRC). (1996). National science education standards. Washington, D. C.: National Academy Press.

Oxford English Dictionary. (2008). OED Online. Retrieved January 18, 2008, from

Oxford University Press. (2007). AskOxford: Oxford reference online. Retrieved December 15, 2007, from

Parr, A. (2007). Hydraulics and pneumatics: A technician’s and engineer’s guide. (2nd ed.). Boston: Butterworth-Heinemann.

Silberstein, E. (2003). Heat pumps. United States: Thomson Learning, Inc.

UPS Press Room (n.d.) Fact sheets. Retrieved March 12, 2008, from

Zapato, L. (n.d.) The inteli-tube pneumatic transportation system. Retrieved February 29, 2008, from [pic]

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