If we double the diameter of Syringe B see Figure 2 the area of the plunger becomes four times what it was. This means a 10kg weight would be supported on 4 square centimetres of fluid. Fluid pressure would only have to exceed So, moving the 10kg object would only require This is the essence of fluid power. Varying the sizes of pistons plunges and cylinders syringes allows multiplying the applied force. In actual hydraulic systems, pumps contain many pistons or other types of pumping chambers that are driven by a prime mover usually an electric motor, diesel engine or gas engine that rotates at several hundred revolutions per minute rpm.
So a system that can develop bar 20 MPa can push with ,N of force from a cylinder about the same size as a can of drink. Mobile equipment is probably the most common application of hydraulics.
Whether its construction, mining, agriculture, waste reduction or utility equipment, hydraulics provides the power and control to tackle the task, and often to provide motive power to move equipment from place to place and over difficult terrain — especially when track drives are involved.
Hydraulics is also widely used in heavy industrial equipment in factories, in marine and offshore equipment for lifting, bending, pressing, cutting, forming and moving heavy work pieces.
Other industries where hydraulics is advantageous:. The principles of pneumatics are the same as those for hydraulics, but pneumatics transmits power using a gas instead of a liquid. Compressed air is usually used but nitrogen, or other inert gases, can be used for special applications. With pneumatics air is usually pumped into a receiver using a compressor. The receiver holds a large volume of compressed air to be used by the pneumatic system as needed.
Atmospheric air contains airborne dirt, water vapour and other contaminants, so filters and air dryers are often used in pneumatic systems to keep compressed air clean and dry, which improves reliability and service life of the components and system. Pneumatic systems also use a variety of valves for controlling direction, pressure and speed of actuators.
Most pneumatic systems operate at pressures of about 10 bar or less. Due to the lower pressure, cylinders and actuators must be sized larger than their hydraulic counterparts to apply an equivalent force. For example, a hydraulic cylinder with a 25 cm diameter piston A pneumatic cylinder using 10 bar air pressure would need a bore of almost Even though pneumatic systems usually operate at much lower pressures than hydraulic systems, pneumatics holds advantages that makes it more suitable in certain applications.
As pneumatic pressures are lower, components can be made of thinner and lighter weight materials such as aluminium and engineered plastics, whereas hydraulic components are generally made of steel and ductile or cast iron. Pneumatic systems are generally simpler because air can be exhausted to the atmosphere whereas hydraulic fluid usually is routed back to a fluid reservoir.
Pneumatics also holds advantages over electro-mechanical power transmission methods. Start with a challenge task to use the provided PFPD schematic Figure 4 and place all of the connection hoses in the correct locations so the PFPD operates as it is designed on the plan.
Then have students answer the handout questions and do a quick write-up of their findings during this exercise. Depending on students' ability levels and time availability, eight worksheets associated with using the PFPD are provided for classroom use on the following topics: fluid flow, Pascal's law, moments and mechanical advantage, fluid power capabilities, Bernoulli's equation, energy storage, linkages, and hydraulic symbols.
See the Attachments section. Can you think of any uses of fluid power in your communities that were not discussed? Where were they located? How were they being used? Was it a hydraulic or pneumatic device? Why do engineers continue to work to improve fluid power? In what areas are they looking at improving? How are engineers trying to improve fuel economy? What work is being done to use fluid power to improve human life? Can you identify devices or systems that do not use fluid power that might be improved with the use of fluid power?
As you have come to realize by now, fluid power is used in many applications. After reading through these case studies, you will understand why fluid power was chosen as the power source and the important role that electronics played in each example.
By this point, you should have a complete understanding how fluid power systems operate and why engineers are continuing to work on improving the efficiency of fluid power applications, expanding the use in transportation sector to reduce fuel consumption, develop human-scaled fluid power applications, and making fluid power safe, quiet, clean and simple to use. Boyle's law: The volume of a gas at constant temperature varies inversely with the pressure exerted on it.
Charles' law: The volume of a confined gas is proportional to its temperature, provided its pressure remains constant. Gay-Lussac's law: The absolute pressure of a confined gas is proportional to its temperature, provided its volume stays constant. Pascal's law: Pressure exerted by a confined fluid acts undiminished equally in all directions.
The amount or quantity of something. Class Discussion Video Summary: After students have viewed the fluid power video s , lead a class discussion about what they discovered.
What was the message s of the video? What is the future of fluid power? Were you surprised to see some of the applications and if so, why? Why did you find certain parts of the video interesting? How do all of these things you saw relate to your lives?
Doing this reinforces students' familiarity with the fluid power terms and definitions. Make sure you have all the supplies you need, depending on the number of students in the class.
Have students perform their "tasks" and report their findings in their notebooks. Alternatively, them do a short write-up to turn in for a grade rather than checking notebooks. Have students share with their classmates what they discovered during their tasks. Since some students did the same tasks as others, discuss why some students had similar or different thoughts during the same task. Students who conducted different tasks gain insight on what the other students learned.
A good background resource for teachers is the U. Navy's personnel fluid power training manual, which provides extensive fluid power background knowledge on the fundamentals of hydraulics and pneumatics in pages.
Beasley, Jr. Fluid Power Training Manual. July edition. Navy, U. Stock ordering : LP Accessed July 12, Accessed 8 July Bordessa, Kris. Accessed 22 July Accessed 18 June Figueras, Antonio. March, Accessed 24 July Accessed 23 July Accessed 20 July Accessed18 July Accessed 25 July Nave, C. Accessed 26 July Accessed 19 July Van den Brink, R.
The contents of this digital library curriculum were developed under National Science Foundation grant no. EEC However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.
Why Teach Engineering in K? Find more at TeachEngineering. Quick Look. Print this lesson Toggle Dropdown Print lesson and its associated curriculum. Pneumatics work the same way hydraulics do, except that instead of liquids, power is transmitted by gas. You can use linear movement or angular rotational movement, with variable operational speeds. According to the NFPA , these are the markets that use hydraulics the most:.
The NFPA recommends these practices to cut energy usage by nearly a third:. How hydraulics work Hydraulics is all about physics. Varying the sizes of pistons plungers and cylinders syringes allows multiplying the applied force. In actual hydraulic systems, pumps contain many pistons or other types of pumping chambers. They are driven by a prime mover usually an electric motor, diesel engine, or gas engine that rotates at several hundred revolutions per minute rpm.
Hydraulic systems typically operate at fluid pressures of thousands of psi. So a system that can develop 2, psi can push with 10, lbs. Off-highway equipment is probably the most common application of hydraulics.
Hydraulics is also widely used in heavy industrial equipment in factories, in marine and offshore equipment for lifting, bending, pressing, cutting, forming, and moving heavy work pieces.
The principles of pneumatics are the same as those for hydraulics, but pneumatics transmits power using a gas instead of a liquid. Compressed air is usually used, but nitrogen or other inert gases can be used for special applications. With pneumatics, air is usually pumped into a receiver using a compressor. The receiver holds a large volume of compressed air to be used by the pneumatic system as needed. Atmospheric air contains airborne dirt, water vapor, and other contaminants, so filters and air dryers are often used in pneumatic systems to keep compressed air clean and dry, which improve reliability and service life of the components and system.
Pneumatic systems also use a variety of valves for controlling direction, pressure, and speed of actuators. Most pneumatic systems operate at pressures of about psi or less. Because of the lower pressure, cylinders and other actuators must be sized larger than their hydraulic counterparts to apply an equivalent force. For example, a hydraulic cylinder with a 2 in.
Even though pneumatic systems usually operate at much lower pressure than hydraulic systems do, pneumatics holds many advantages that make it more suitable for many applications. Because pneumatic pressures are lower, components can be made of thinner and lighter weight materials, such as aluminum and engineered plastics, whereas hydraulic components are generally made of steel and ductile or cast iron.
Pneumatics also holds advantages over electromechanical power transmission methods. Electric motors are often limited by heat generation. Heat generation is usually not a concern with pneumatic motors because the stream of compressed air running through them carries heat from them.
In fact, even without special enclosures, electric motors are substantially larger and heavier than pneumatic motors of equivalent power rating. Plus, if overloaded, pneumatic motors will simply stall and not use any power.
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