Fluid Power Systems
Procedures for Teachers is divided into four sections:
-- Preparing for the Lesson.
-- Conducting the Lesson.
-- Additional Activities.
-- Managing Resources and Student Activities.
- 2 12cc veterinary syringes per team of students.
- 2 20cc veterinary syringes per team of students.
- 2 30cc veterinary syringes per team of students.
- 36" plastic tubing per team of students.
- 11"x17" graph paper.
- 1' rulers.
- Assorted rubber bands.
- Wood glue. (Don't use hot glue because it stretches too much.)
- Clear pine wood, assorted lengths.
- 12"x12"x3/4" plywood.
- Miter saw. (A power miter saw would be a big help.)
- Assorted screws & fasteners.
- Test tubes.
- Test tube racks.
You will need at least one computer with Internet access to complete this lesson. While many configurations will work, we recommend:
-- Modem: 28.8 Kbps or faster.
-- Browser: Netscape Navigator 3.0 or above or Internet Explorer 3.0 or
-- Macintosh computer: System 7.0 or above and at least 16 MB of RAM.
-- IBM-compatible computer: 386 or higher processor with at least 16 MB
of RAM, running Windows 3.1. Or, a 486/66 or Pentium with at least 16 MB of
RAM, running Windows 95 or higher.
For more information, visit What You Need to Get Connected
in wNetSchool's Internet Primer.
The following sites should be bookmarked:
Reeko's Mad Scientist Lab
Students find out about Pascal's Law by reading about an experiment to make a "submarine" sink. It's fun!
Digger Jr. Explains
This clearly outlined and vivid description of hydraulics and hydrostatics makes these concepts easy for all to understand.
STATES OF MATTER
Using this site, students discover the four states of matter and the laws that govern them.
This site shows some good examples of homemade hydraulic devices that were created from simple materials.
This technology learning activity requires about 15 class periods.
Design Brief and Criteria:
Distribute and discuss the Design Brief, in Organizers for Students. Ask students the question, "What are fluids?"
Break students into teams of 2. Give each student team the Research Log, in Organizers for Students. Students should visit each site and "log in" any information that is relevant to their design problem.
Students should begin research on the topic of hydraulics/pneumatics with the following sites. (Encourage your students to search for more information. This is just a start.)
Reeko's Mad Scientist Lab
Digger Jr. Explains
(See the "Brain Teaser" for a sample problem to work out with your students to understand mechanical advantage in fluid systems.)
The Internet Science Room
ANSWER KEY to the Research Log
1. What are the four states of matter?
- Solid, liquid, gas, and plasma.
2. What are the characteristics of fluids?
- They take on the shape of their container; they "flow."
3. Define the following terms as they relate to fluid power:
- Pascal's Law: Any force applied to an enclosed fluid is transmitted in all directions to the walls of the container.
- Area: The measurement of length x width; for a circle, (pi)r2.
- Pressure: Expressed in pound per inches squared (PSI), it is the force divided by the volume area.
- Force: Mass x acceleration.
- Mechanical Advantage: The amount of energy that a mechanism reduces in a force.
4. Explain why gases are used for some fluid systems and liquids are used in others.
- Gases are used primarily because of the portability of the systems and ease of set-up. Liquid systems are used where higher power and precision is required.
5. Solve the problem portrayed in the diagram provided in the Research Log, in Organizers for Students.
- Area of Piston A: 3.14 x (.5)2 = .785 in.sq.
- PSI of system: 50 lbs. / .785 in.sq. = 63.694 PSI
- Output force at Piston B: 63.694 PSI x 113.04 in.sq. (area of piston "B") = 7199.970 lbs.
6. Discuss the pros and cons of hydraulics and pneumatics.
- Answers may vary but here is one possibility: Pneumatic systems are portable and less expensive but do not provide the same power or precision as hydraulic systems. Hydraulic systems are more accurate and provide more power than pneumatic systems. However, hydraulic systems are not as easily portable. They use chemical fluids that can pollute, and are more costly.
7. List a minimum of 5 applications of fluid power we see in our every day lives.
- Answers may vary. A Back Hoe, a nail gun, "Jaws of Life" tool, car brakes system, and an industrial robot are some possibilities.
Students should sketch or download pictures of at least four possible designs for their chosen solution to the assignment in the Design Brief, in Organizers for Students. Students should make notations on the designs, making reference to any special features. This should relate directly to the information gathered from the students' Internet research.
Teams should discuss the pros and cons of the design they have found (or come up with on their own). After comparing their choice to the design criteria, instruct them to choose the one they think will work best for the given situation.
Have the teams complete a set of detailed, full size, working drawings of the design they have chosen. This should include dimensions and any other important information needed to build their prototype.
When the teams complete the design phase of the activity, they should begin construction using the tools and materials outlined in the Design Brief, in Organizers for Students.
Testing, Evaluation & Redesign:
At the end of the construction phase, organize a testing session for the hydraulic arms. Try to make this a BIG DEAL! Things like lab coats and safety gear will add to the atmosphere. Set up a mock isolation chamber so you can "remotely" control the robots from "outside" the enclosure. Video taping also makes for a good follow up, as you will be able to review each step of the testing to evaluate and discuss key points with your students. Students should record data as the testing takes place, make notations about the operation of their design, and record any problems that occur.
At the conclusion of testing, have each team compile the results and complete a portfolio that includes the research, design possibilities, chosen design with explanation, any pre-construction sketches, and a summary and conclusion from the testing results for possible redesign and changes for a future attempt.
Science: Study the states of matter. Discuss what type of matter falls into the fluid category. Become familiar with and discuss Pascal's Law.
Language Arts: Have students give an oral presentation of their design to the class. Students should also turn in a documentation portfolio to reflect their work on this design problem.
Mathematics: Calculate the area of a circle using (pi)r2. Calculate pressure, force, and mechanical advantage in a fluid system. Utilize the formulas: Pressure = Force / Area and Force = Pressure x Area.
One Computer in the Classroom
If you have access to one computer in your classroom, you can organize your class in several ways. Divide your class into two groups. Instruct one of the groups to do paper research while the second group is working on the computer. Bring in books, encyclopedias, etc., from the library for the group doing paper research. When the groups have finished working, have them switch places.
If you have a big monitor or projection facilities, you can do Internet research together as a class. Make sure that every student in your class can see the screen, go to the relevant Web site(s), and review the information presented there. You can also select a search engine page and allow your students to suggest the search criteria. Again, bookmark and/or print the pages that you think are helpful for reference later.
Several Computers in the Classroom
Divide your class into small groups. Groups can do Internet research using pages you have bookmarked. Group members should take turns navigating the bookmarked site.
You can also set the class up so that each computer is dedicated to certain sites. Students will then move around the classroom, getting different information from each station.
Using a Computer Lab
A computer center or lab space, with a computer-to-student ratio of one to three, is ideal for doing Web-based projects. Generally, when doing Web-based research, it is helpful to put students in groups of three. This way, students can help each other if problems or questions arise. It is often beneficial to bookmark sites for students ahead of time.
Submit a Comment: We invite your comments and suggestions based on how you used the lesson in your classroom.