Peace Corps appropriate community technology/Classical Mechanics: Principles of Pedal

Session 5. Classical Mechanics: Principles of Pedal/Treadle Power[edit | edit source]

Total time:	2 hours
Objectives:	To demonstrate and discuss the mechanical principles of torque, momentum, inertia end sprocket ratios To discuss the application of these mechanical principles to pedal/treadle-powered devices To practice facilitation skills
Resources:	Meriam, Mechanics Attachment III-5-A, "Demonstration of Torque" Attachment III-5-B, "Demonstration of Momentum and Inertia" Attachment III-5-C, "Demonstration of Sprocket. Ratios" Attachment III-5-D, Ratio Designs" Worksheet;
Materials:	Newsprint and felt-tip pens; materials listed in attachments.

Plan for time at the end of each of the three demonstrations for feedback on the facilitation skills of the individual giving the demonstration. You can encourage this feedback by asking the facilitator what he or she feels was best during the demonstration and where improvements could be made.

Step 1. (40 minutes)

Have the participant/facilitator demonstrate the concept of torque as outlined in Attachment III-5-A.

Trainer Notes You should fill in any points missed or not covered to your satisfaction during all three of the demonstrations or discussions.

Step 2. (40 minutes) Have the second participant/facilitator demonstrate the effects of momentum and inertia as outlined in Attachment III-5-B.

Step 3. (40 minutes) Have the third participant/facilitator demonstrate the principles of sprocket ratios as outlined in Attachment III-5-C.

Trainer Notes At the end of this session, distribute Attachment III-5-D, the "Ratio Designs" worksheets, explaining that the worksheets should be completed for the next day's session.

DEMONSTRATION OF TORQUE

Through this demonstration, the participants will gain practical understanding and experience with the effects of torque and its relationship to pedal/treadle power devices.

Total time:	40 minutes
Materials:	2 boards of equal length and nails

Procedures:

Step 1.

(15 minutes/Steps 1-4) Nail 2 boards together in a V-shape.

Step 2.

Have a participant grasp the two boards at the middle and attempt to pull them apart by opening the V. Point out the force required to move the boards.

Step 3.

Repeat the experiment by having another participant grasp the ends of the boards.

Step 4.

Compare the force required to move the boards when they are grasped at different distances from the juncture.

Note The conclusion will be that it takes much less force to pull boards apart at the end mark, i.e., equal forces exert more effect on the juncture when they are at a greater distance from it. Encourage the participants to express the relationship between applied force and the distance at which it is exerted, using the boards as an example. Such a relationship describes torque and may be expressed in the following formula: torque = force applied x distance of applied force to the point of juncture

Step 5. (20 minutes)

Facilitate a discussion of the methods that might be used to minimize the effects of torque.

Step 6. (5 minutes)

Encourage feedback on your facilitation skills.

DEMONSTRATION OF MOMENTUM AND INPRTIA

This demonstration will enable the participants to experience the effects, parameters and relationships of momentum and inertia to pedal/treadle power.

Total time:	40 minutes
Materials:	Wheel or disk, axle, 4 weights (total weight approximately equals that of the wheel or disk)

Procedures:

Step 1. (15 minutes/Steps 1-5)

Mount the wheel or disk on a shaft so that it can be easily rotated.

Step 2.

Have a participant rotate the wheel at an approximate set speed, taking note of the force required to start it rotating and the time it takes to coast to a stop after the force is withdrawn. Then, have a participant again rotate the wheel up to speed and then try to stop it quickly, noting the force required to stop the motion.

Step 3.

Distribute four weights equally around the outside of the wheel and repeat the procedure.

Step 4.

Ask the participant to note the effects of the added weights.

Note The conclusion will be that it takes more effort to start the wheel rotating with the added weight but that the wheel rotates freely for a longer time.

Step 5.

Encourage a discussion of the relationships between parameters of momentum (which are the initial weight of the wheel and its added weights), the wheel's rotational velocity and its radius.

Step 6.

(20 minutes) Facilitate a discussion of the application of the principles of momentum and inertia to pedal/ treadle design.

Step 7.

(5 minutes) Encourage feedback on your facilitation skills.

DEMONSTRATION OF SPROCKET RATIONS

This demonstration allows the participants to experience the effects, parameters and relationship of sprocket ratio to pedal/ treadle power.

Total time:	40 minutes
Materials:	Multiple speed bicycle

Procedures:

Step 1. (15 minutes/Steps 1-4)

Put the bicycle in low gear and lift the rear wheel off the ground. Ask the participants to observe how many times the rear wheel rotates for each revolution of the pedal crank.

Step 2.

Change the gear ratio to a higher gear and repeat Step 1.

Note In the above two steps, ask the participants to observe the relative difference in force necessary to turn the pedal crank.

Step 3.

Have the participants develop the formula which defines the relationship between sprocket sizes and rotation speed.

Note This relationship is defined as:[[File:]]

Step 4.

Facilitate a discussion of the potential mechanical advantage when sprockets are oriented in the proper fashion.

Note The conclusion will be that transferring energy from a small to a large sprocket results in a velocity loss but in a mechanical advantage or gain.

Step 5. (20 minutes)

Facilitate a discussion of the application of the principles of sprocket ratios to pedal/treadle power.

Step 6. (5 minutes)

Encourage feedback on your facilitation skills.

RATIO DESIGNS WORKSHEET

1. Given the mobile dyne pod designed to power a food grinder that operates at 100 revolutions per minute, size the sprocket that will be connected to the grinder shaft:

Available sprockets:

35 teeth

42 teeth

48 teeth

18 teeth

22 teeth

30 teeth

[[File:]]

RATIO DESIGNS WORKSHEET 1

1. Given the stationary dynapod, size the two sprockets in question to provide the required 400 revolutions per minute output in low gear on the bicycle.

1st gear: 1.4/1

2nd gear: 1/1

3rd gear: 111.4

[[File:]]

RATIO DESIGNS WORKSHEET 2

1. Design a mobile dyne pod unit that will provide the driven output shaft speed of approximately 1,200 revolutions per minute necessary to power a bench grinder. The bicycle used will have a front sprocket of 48 teeth and a rear hub sprocket of 18 teeth.

Available sprockets:

35 teeth

42 teeth

48 teeth

18 teeth

22 teeth

30 teeth

[[File:]]

RATIO DESIGNS WORKSHEET 3

1. Design a system which will deliver power in a linear mode for a water pump designed to operate at 15 cycles per minute. Pedaling speed of 60 revolutions per minute will be used with a belt/pulley combination. The pump has a driving rod throw of 8".

Session 6. Use of Appropriate Aids to Communication[edit | edit source]

Total time:	2 hours
Objectives:	To discuss the need for creating relevant audiovisual aids for use in development work To identify and list various aids to communication which can be used in developing countries To make and use some appropriate aids to communication
Resources:	Fuglesang, Applied Communication in Developing Countries Peace Corps, Visual Aids Number 2 Pett, Audio-Visual Communication Handbook Bertrand, Communications Pretesting Attachment III-5-A, "Extension Skills" Attachment III-6-B, "Selecting Communication Tools"
Materials:	Newsprint and felt-tip pens, a variety of examples of audio and visual aids, i.e. posters, flannel graphs, puppets, games, newsletters, papers, photo novels, comic strips, cassette tapes, slide/tapes, filmstrips, overhead transparencies, etc,

Trainer Notes The examples listed above are particularly effective if they have been developed for use in a Third 'World setting and carry messages pertaining to development issues, i.e., health, nutrition, sanitation, literacy, family planning, agriculture, etc.

Procedures:

Step 1. (15 minutes)

Begin the session by reading the "Story of the Tsetse Fly" from Applied Communications in Developing Countries. Then present a short talk on the need for creating relevant audio-visual aids for use in development work.

Trainer Notes A useful reference source is located on pp. 88-114, "Creating Visual Aids," in Applied Communications in Developing Countries.

Step 2. (10 minutes) Have participants brainstorm a list of different communication aids that might be applied in development projects.

Step 3. (10 minutes) Referring to the list, facilitate a discussion of the strengths and weaknesses of different communication aids for use in development work.

Step 4. (20 minutes) Pass out the different examples of communication aids, briefly describing each one. Encourage any questions or discussion.

Trainer Notes Also circulate copies of the resource materials for this session and discuss them with the group.

Step 5. (10 minutes) Distribute Attachments III-6-A, "Extension Skills," and III-6-B; "Selecting Communication Tools," and review them with the group.

Step 6. (55 minutes) Have participants form small groups and prepare appropriate audio-visual aids for use in the next session.

Trainer Notes Phase III: Session 7 which follows, "Maternal and Child Health," includes group presentations on health topics. Encourage the groups to apply what they have learned in this session to prepare for the presentations in the next session, i.e., incorporating a poster or other visual aid, a game, a skit, a song, a script for a radio broadcast, etc. Also encourage the participants to apply this knowledge in their presentations at the end of technical phases and during the Energy Fair.

EXTENSION SKILLS: Important Points to be Considered for Successful Education and Communication

1. Be prepared. Know what you are doing, where you are going and what you want your audience to know when they leave. Don't prepare your talk an hour before you give it.
2. Always do a practice run of whatever it is you are demonstrating before you get up in front of the group to teach.
3. Start off with a very small chunk of information to be taught. For example, "How to Build a Stove" would be too broad a topic. Change it to "Building the Base."
4. People learn best by doing. The more concrete you can be, the better. For example, if you are doing a talk on how to make a particular type of soup, have everyone make it and taste the soup.
5. People remember main points better when presented with visual aids. Illustrate your main points and use the drawings during your talk. Also, people tend to understand complex or abstract concepts if they can visualize them. Also remember that points or concepts you find simple, others may find difficult. Be sensitive to your audience and explain points thoroughly.
6. Visual aids and/or graphs should be clear, depicting objects with which the people are familiar. Photographs or pictures cut from magazines are often mere easily understood than hand-drawn pictures.
7. Changing color and lettering can draw more attention to the visual aids. However, visual aids may be distracting, confusing or misunderstood when they do not mirror people's reality.
8. A vocabulary list of important things, steps and materials in the demonstration can be useful to the demonstrator as well as to the audience.
9. The demonstration should never take place above the audience's line of vision.

10. People remember things that are unusual or make them laugh. But don't overdo it.

11. Physical conditions are important. The demonstration should take place in the lightest part of the room or area. Rooms should be freed of all other distractions. Effort should be made to make everybody physically comfortable, etc.

12. It's better to have an active audience than a passive one.

13. Don't read your material.

14. Keep eye contact with your audience. In this way, you will build a rapport with them. Also, they will feel like you are talking to them and not at them.

15. Respect the audience members who already know how to do the thing that you're demonstrating and get them involved in helping you with the presentation.

16. Repeat the main points. For example, state them at the beginning of your talk, in the middle and at the end. Again the next day, repeat the main points or elicit them from your group before you go into any new information. In other words, build on the previous information.

17. Reinforcement activities following a talk can facilitate learning.

18. Always minimize the cost of the thing being demonstrated, making sure that the people have the economic resources necessary to do it on their own. Try to utilize materials found in the immediate area.

19. When the demonstration involves making something, it is always a good idea to have a finished example to show to the audience.

20. Variety in presentation styles and environment are important.

21. Your talk should contain an introduction that gives a purpose for the information you are going to give. Set the stage for your talk.

22. Try not to use very technical words in the demonstration.

23. Organize your information. For example, time/order, cause/effect, etc.

24. Whenever possible, relate what you are demonstrating to the local customs.

25. Keep your demonstration short and limited to the time of day and amount of time that the people have free.

26. If the demonstration involves several steps, either write or draw them so the audience has something to follow as you go, but be sensitive to the fact that some people do not know how to read or follow diagrams.

27. Try and involve as many of the people's senses as possible: taste, smell, touch, sight, sound.

28. Your personality is important. Smile and be friendly.

29. Speak slowly and clearly. You're probably speaking slowly enough when you think you're going too slow.

30. Don't talk down to your audience. Show them the respect you want them to show you.

31. At the beginning of the demonstration, explain briefly what you are intending to do. At the end, summarize what it is that you have done.

32. Be sensitive to your audience. If they are getting restles, you may be going too fast, going on for too long or they may not be understanding you.

33. BE YOURSELF !

Taken from CHP, Guatemala, Peace Corps Training Facility

SELECTING COMMUNICATION "TOOLS"

Visual Aid		General Description		Recommended Audience Size		Advantages		Disadvantages
Chalkboard		Rigid surface painted green or black on which one can write or draw with chalk.		10 to 30 people. If used with more a large board is needed and careful audience placement is necessary.		Inexpensive. Can be homemade easily maintained minimum of preparation. Used day or night. Audience participation.		Transport can be difficult in remote areas. Limited to the user's artistic ability.
Flannel Board		A piece of flannel flannelette terry cloth or felt cloth attached to a rigid surface on which cutout figures will adhere if backed with flannel or felt cloth sand paper or glued sand.		15 to 20 people. Audience size depends on the size of the flannel hoard and the size of the figures that are being used.		Inexpensive. Easily made from local materials. Easily maintained and transported in remote areas. Figures can be used in different presentations. Ideal for showing sequence of events and reviewing lesson as figures can be brought back on the board.		Requires considerable advance preparation. Difficult to use out of doors if there is any wind. Some artistic ability is required if making homemade figures.
Posters		A message on a large sheet of paper and with an illustration and a simple written message.		No limit because it is not necessary for everyone to look at a poster at the same time.		Inexpensive. Easy to make. requires a minimum amount of time to prepare and use. Easy to transport.		Deteriorate rapidly. Can confuse audience with too much or too little information. Need some artistic ability if making own posters.
Flip Charts		Illustrations on paper or cloth, usually larger than 21 cm by 27 cm; hound together with rings or string. They flip over in presentation.		15 to 30 people. Audience size depends on the size of the flip chart illustration.		Inexpensive. Can be homemade and can he easily transported. Good way to give information in sequence; because they are hound illustrations stay in sequence.		Deteriorate with constant use. Some artistic ability required if making homemade flip-charts.
Flash Cards	Illustrations made on heavy paper that is usually smaller than 21cm by 27cm. The illustrations are not bound but are arranged in sequence.		5 to 15 people. Because the illustrations are small no more than 15 people should be in the audience.		Inexpensive. Can be homemade. Very easy to transport. Good way to give information in sequence to small groups.		Deteriorate with constant use. Some artistic ability required if making homemade flashcards. Easy to get out of sequence. Limited to small groups.
Bulletin Boards	A surface at least 3/4m by 1m into which stick pins can be placed. Drawings photos and lettering can be displayed on the board.		No limit because it is not necessary for everyone to look at the bulletin board at the same time.		Inexpensive. Can be homemade from local materials. Good way to present a "changing" message in areas where people gather.		If out of doors weather damage can occur. Constant supply of good educational material to put on the board is needed.
Demonstration	Using actual ingredients tools or land, the educator shows how something is done. Either at that time or soon afterward each audience member displays an ability to do the new thing.		1 to 30 people. Because it is difficult for an educator to follow up on more than 30 persons this is the recommended limit.		Excellent way to use actual materials in a real situation. Uses local materials. Easy to understand by people not used to looking at illustrations. Good way to get audience participation.		Takes a lot of planning and preparation.
Film	Color or black & White 16mm or 8mm cinema film with sound projected on a screen or wall.		30 to 100 people. Groups can be larger -- but it is difficult to have any discussion with larger groups.		Dramatic and gets the audience's attention. Shows motion and therefore helps explain stepby-step and time sequence very well.		Very expensive; requires expensive equipment electricity and dark projection area. Difficult to transport and operate.
Slides	35mm film in plastic or cardboard mounts 5cm by 5cm. In color or black & white they are projected on a screen or a wall.		About 30 people. Though slides can be used with more people the educator can stimulate better discussion among a smaller group.		Dramatic less expensive than cinema e film excellent way to bring distant things to audience and to show time sequence. Batteryoperated projectors available. Local photos easily made.		Easy to damage easy to get out of sequence and project upside down or sideways. Requires projection equipment needs electricity or batteries and darkened projection area.
Filmstrips	Strip of 35mm film color or black and white. Photographs in sequence. Filmstrip projected on screen or wall. Uses projector with filmstrip adapter. Filmstrips horizontal or vertical format.		About 30 people. Though filmstrips can be used with more people the educator can stimulate hefter discussion with a group of this size.		Dramatic less expensive than film and slides. Once inserted correctly in projector impossible to get out of sequence. tan show photos of the real thing and shows sequence in time. Battery-operated projectors available. Relatively easy to transport.		Requires projection equipment can he damaged requires either mains or battery-supplied electricity. (Sometinres batteries are expensive.) Requires darkened projection area. Limited appropriate filmstrips available.
Adopted from WORLD NEIGHBORS IN ACTION newsletter.

Session 7. Maternal and Child Health: Part 2[edit | edit source]

Total time:	2 hours
Objectives:	To prepare and give a presentation to the group concerning maternal and child health issues To discuss the role of the Volunteer in improving maternal and child health To use a structured meeting format
Resources:	Refer to Phase III: Session 1, "Maternal and Child Health: Part 1"
Materials:	Newsprint and felt-tip pens; presentation guidelines (Phase III : Session 1, Step 8)

Trainer Notes In this session, groups formed in Phase III: Session I will present the results of their investigations into maternal and child health topics. The planning for this session was done in Part 1 (Phase III: Session 1). The groups are expected to use "The Four Roles for a Structured Meeting" as a format for their presentations.

Step 1. (5 minutes)

Briefly introduce the session objectives and outline the activities.

Step 2. (5 minutes)

List the order of the presentations on newsprint and post the presentation guidelines (See Phase III: Session 1, Step 8).

Step 3. (one hour, 30 minutes)

Have the groups give their presentations.

Step 4. (20 minutes)

Discuss the presentations and the success in meeting the session objectives.

Trainer Notes Have the recorders present their notes from the presentation and ask each process observer to comment on the meeting. Discuss the sesion by raising the following questions: Did speakers keep to the issues and follow presentation guidelines? How do you feel about your role as a Volunteer in relation to issues raised? To what degree can we generalize about each of these issues? Did you learn about issues (or parts thereof) previous, unknown to you? What were effective ways people presented information?

Session 8. Part one: Familiarization With Materials and Tools[edit | edit source]

Total time:	1 hour
Objectives:	To identify and discuss the various tools and material resources available at the training site and/or in the local community To discuss the role of available material in the design process
Materials:	All local relevant resources: wood, metal, bearings, ropes, pulleys, pipe, bamboo, fastenings, etc. and the tools to work them

Procedures:

Step 1. (5 minutes)

Present the session objectives and review the activities.

Step 2. (10 minutes)

Facilitate a discussion of the importance of taking into account available resources in de signing a pedal/treadle device.

Trainer Notes Explain that ideally the design of any pedal/treadle or other appropriate technology device should use materials that are available locally. Mention that before designing any device, it is important to thoroughly assess what resources will be available.

Step 3. (45 minutes)

Take the group on a tour of the training site and/or local community, explaining and/or demonstrating the uses, qualities and purposes of all available materials and tools.

Trainer Notes Encourage a great deal of questions and experimentation so that by the end of the tour, participants are completely familiarized with all available resources. You should pay special attention to touring any available workshops, using this time to introduce the topic of shop safety (including location of fire extinguishers, personal safety and proper use of tools).

Session 8. Part Two: Familiarization With The Bicycle[edit | edit source]

Total time:	1 hour
Objectives:	To discuss the major issues regarding the promotion and use of bicycle-powered devices in the Third World To disassemble a bicycle and identify the parts
Materials:	Newsprint, felt-tip pens, bicycles, wrenches, screwdrivers, hammers, etc.
Resources:	McCullough, Pedal Power Cuthbertson, Anybody's Bike Book Attachment III-8/2-A, "Bicycle Diagram"

Trainer Notes This session is optional and should be used at your discretion, depending upon the extent to which you wish to focus on the use of bicycles during the pedal/treadle phase. You should, however, spend some time discussing the issues involved in the use of bicycles in developing countries (See Step 1). Decisions regarding the extent to which bicycles will be emphasized during the phase should depend upon points raised during this discussion.

Step 1. (15 minutes)

Present the session objectives, distribute Attachment III-8/2-A, "Bicycle Diagram," and facilitate a discussion of the mayor issues involved in the promotion and use of bicycle-powered devices in developing countries.

Trainer Notes During the discussion you should stress the following points: In many developing countries, bicycles are scarce and their primary use is for transportation. Given their scarcity and expense, it is unlikely that people would be willing to disassemble their bicycles for use in pedal-powered devices. If bicycles are used for power generation, mobile dynapod designs are more suitable than fixed designs. Keep this discussion as specific as possible to the countries in which the participants will be working.

Step 2. (15 minutes)

Have the participants form small groups. Provide each group with a bicycle and ask that they identify the parts of the bicycle and develop a procedure for disassembling it.

Trainer Notes Explain that the group members should assist one another in identifying the bicycle parts. When the groups have developed their procedure for disassembly, have each group verify the procedure with you.

Step 3. (30 minutes)

Have the groups disassemble the bicycles.

Trainer Notes As the groups are working, circulate among them, encouraging participants to help one another and to try working together as cooperatively as possible.

Step 4. (15 minutes)

Reconvene the groups and encourage a discussion of the disassembly activity.

Trainer Notes Stimulate this discussion by asking the following questions: Did you learn anything new about bicycles during this activity? Can you think of any ways in which bicycles might be used for generating power in your work as Peace Corps Votunteers? Was there anything which occurred during the activity that fostered the development of a sense of cooperation among your fellow group members?

[[File:]]

BICYCLE DIAGRAM

The above illustration is that of a ten-speed bicycle, which is the most complex type.

Other types, such as single and three-speed, do not have multiple front sprockets and derailleur.