This activity is comprised of two parts: Part 1 - Investigating Pneumatics and Hydraulic Systems Handout: 1 ½ - 2 class periods at 40 minutes each. Part 2 - Creating the hydraulic arm: three 40-minute classes (This activity can be done in fewer class periods, but giving students this amount of time enables them to test numerous design ideas and further understand the engineering design process and the underlying concepts. 2 Between $20 and $30 depending on the number of groups.

Students design and build a mechanical arm that lifts and moves an empty 12-ounce soda can using hydraulics for power. Small design teams (1-2 students) design and build a single axis for use in the completed mechanical arm. One team designs and builds the grasping hand, another team the lifting arm, and a third team the rotation base. The three design groups must work to communicate effectively through written and verbal communication and sketches.

Just like engineers, students in this activity follow the steps of the engineering design process. Engineers develop hydraulic arms for a variety of reasons. Hydraulic arms can be used in situations that are too difficult or dangerous for people to deal with directly or in automated systems. Examples include arms that lift heavy weights and arms that hold a load and unload them into a specific position. axis ball and socket engineering design process fixed joint hinge joint hydraulics joint pivot prototype pneumatic system After this activity, students should be able to: Identify the steps of the engineering design process. Follow along with the engineering design process as they design and build. Represent solutions to a design process in multiple ways. Describe and explain features and purpose of a design. Have a basic understanding of hydraulic and pneumatics. Each group needs: plastic syringes (online source: McMaster-Carr. for $1 per syringe) plastic tubing (source: pet supply store for $20) various wood scraps bolts, screws, nuts, washers other APPROVED materials 1 empty soda can To share with the entire class: tape 20 x 20 piece of wood or cardboard to serve as a wall drill (for teacher use or with appropriate supervision) saw (for teacher use) empty soda can Have you ever seen a car lifted into the air at an auto repair place? Have you ever wondered how an elevator can lift a load of people up into the air? Well, after our project today, you'll have a better understanding of how these work, because we're going to look at hydraulic systems. Hydraulic systems use a liquid, usually oil, to transmit force. This system works on the same principles as other mechanical systems and trades force for distance. Hydraulic systems are used on construction sites and in elevators. They help users perform tasks that they would not have the strength to do without the help of hydraulic machinery. They are able to perform tasks that involve large amounts of weight with seemingly little effort. Involving or moved by fluid under pressure. A working model of a new product or new version of a product. Involving the mechanical properties of air and other gases. Hydraulic systems are used in many different types of machines: control surfaces on airplanes, elevators, automobile lifts, and backhoes. The idea behind a hydraulic system is that force is applied to one point and is transmitted to a second point using an incompressible fluid. You can find detailed background information oon how hydraulic machines work at http://science.howstuffworks.com/transport/engines-equipment/hydraulic1.htm. Before the Activity Build a soda can test area that is 20 x 45 centimeters. Use tape to mark the perimeter of the test area. Place a 20 x 20 cm tall wall in the middle of the test area so the area is divided into two equal areas, each measuring 20 x 22 cm. Draw a circle on each side of the wall. Write "Start" in one and "Finish" in the other. The circles should be ~4 centimeters from the wall and 6 centimeters from the sides. These dimensions are flexible. Smaller would be easier and larger dimensions are harder. Print the journals and handouts. Gather materials. Divide the class into groups of two students each. Each design team will: Research the engineering design process and answer the questions on the Investigating Pneumatics and Hydraulics Systems Student Handout. Research possible solutions to the challenge. Tips: Look for pictures of other mechanical arms (or parts of arms) that perform functions similar to the ones that they must perform. Think about the connection between their team's component and the components it is connect to. The connections are the most challenging part! Develop a portfolio (a bunch) of sketches that attempt to solve the problem. Share with the entire design team. Upon identifying a promising design, brainstorm with the next design team regarding attaching them together. Critique (be nice, constructive) the designs and make a short list of pros (+) and cons (-) for each idea. Identify the best ideas and vote to decide upon them. Make final engineering sketches of the parts that are needed. Construct the prototypes, noting changes, modifications, failures and successes. It is perfectly fine to mark up your engineering sketches. Show your work! Test the prototype. TRY TO MAKE IT FAIL. What do you have to do to get it to fail? Can you redesign it to prevent that from happening? Make your design the best it can be. (Students like to make their designs fail. They understand that as an instruction and see it as a good mindset for testing prototypes.) Redesign and reconstruct. Retest. Present the portfolio of marked-up drawings, the finished arm, and demonstrate the arm to the class. Design Check List (pdf) [Share this outline of the process that students should be following] Hydraulic Arm Rubric (pdf) Investigating Pneumatics and Hydraulic Systems Student Handout (pdf) Hydraulic Arm Design Journal (pdf) Cut and drill the wood if students do not have experience. See Researching the Engineering Design Process Handout Arm Investigating Questions Design Check List Post Activity Assessment Evaluate the student project using the attached Hydraulic Arm Rubric, with criteria on research, imagining-planning-improving, creativity, written or oral sharing, and how the mechanism meets the challenge. Carpenito, K. and E. Chilton. Hydraulic Arms Challenge. Posted January 2006. Accessed November 7, 2011. (activity inspiration) https://docs.google.com/View.aspx?docid=ah7pxzjtrzfd_baddp39ndp3dv Hydraulic Arm Research. Posted January 27, 2006. Beebe School of Engineering. Accessed November 7, 2011. (a list of references to support this activity, including info on the arm joint and the engineering design process) http://k12engineering.blogspot.com/2006/01/hydraulic-arm-research.html Brain, Marshall. How Hydraulic Machines Work. How Stuff Works. Accessed November 7, 2011. http://science.howstuffworks.com/transport/engines-equipment/hydraulic.htm