Cover Image
close this book Appropriate community technology - A training manual
close this folder Phase III: Pedal/treadle power
View the document Phase III Calendar
View the document Session 1. Maternal and child health: part 1
View the document Session 2. The path of the sun
View the document Session 3. Introduction to pedal/treadle power
View the document Session 4. Design considerations for pedal/treadle power
View the document Session 5. Classical mechanics: principles of pedal/treadle power
View the document Session 6. Use of appropriate aids to communication
View the document Session 7. Maternal and child health: part 2
View the document Session 8. Part one: familiarization with materials and tools
View the document Session 8. Part two: familiarization with the bicycle
View the document Session 9. Introduction to design considerations
View the document Session 10. Presentation of designs
View the document Session 11. Construction of pedal/treadle-powered devices
View the document Session 12. Blacksmithing and metalwork
View the document Session 13. Appropriate technologies for health
View the document Session 14. Case studies in community health
View the document Session 15. Preparation for pedal/treadle presentations* *
View the document Session 16. Heat transfer
View the document Session 17. The role of the volunteer in development: international development part 1: the green revolution: successes and failures
View the document Session 18. Presentation of pedal/treadle-power devices
View the document Session 19. Volunteers in development part one. women in development
View the document Session 20. Mid-program evaluation part one : program evaluation

Session 9. Introduction to design considerations

Total time:

4 hours

Objectives:

* To review and discuss the different qualities of foot-powered devices

* To review and discuss the basic concepts of the design and construction process

* To design a foot-powered device

Materials:

Chalkboard, modeling materials (corks, pins, string, straws, glue, wire, toothpicks, rubber bands, tins, etc.

Resources:

* Attachment III-9-A, "List of Qualities of Foot-Powered Devices"

* Attachment III-9-B, "The Design Process"

* Hommel, China at Work

Trainer Notes

This session should be scheduled at the end of the day so that the participants can continue their design project at home and have it ready for presentation the following day.

Procedures:

Step 1. (5 minutes)

Present the session objectives and activities.

Step 2. (30 minutes)

Distribute Attachment III-9-A, "List of Qualities of Foot-Powered Devices." Review the list, encouraging questions, comments and discussion.

Trainer Notes

Explain that the better one can match the incoming energy source to the energy need, the simpler and more efficient the device can be. As an example, discuss the Chinese pedalpowered chain-and-washer pump, noting that the energy type and amount are so well matched to the energy needed that there is no requirement for a power system: it is direct-drive.

While reviewing the list, ask the participants to define the terms "rotary" and "reciprocating." Discuss the possible applications of each drive system and their limitations.

Step 3. (1 hour)

Distribute Attachment III-9-B, "The Design Process," and review the process outlined. Encourage questions, comments and discussion.

Trainer Notes

* Draw Figure "At" from the attachment on the chalkboard. Review the diagram, emphasizing that no design is complete until it has been tested and retested and that every new design requires redesign and rebuilding. Ask the participants to give examples of design and redesign.

* Referring to the attachment (Part II), move the discussion on to the criteria for a design, emphasizing that specific criteria are more useful than general ones. Review the criteria found on the attachment.

* Draw Figure "B" on the chalkboard and explain that it is a more detailed look at the design process. Take the participants through the process, asking them for an example or offering an example. Ask at which point in the process one needs to consider the various qualities of foot-powered devices discussed earlier in the session.

* Conclude the discussion by explaining that they will be using this process in the design of their devices.

Step 4. (2 hours, 25 minutes)

Have the participants form small construction groups and explain that the remaining time should be used to prepare a design based on the criteria list for a foot-powered device that will be presented in the next day's session.

Trainer Notes

* Tell the participants that they will be working with their groups for the remainder of the phase. Explain that since they will be working together, they should be aware of and sensitive to group processes that are occurring. Suggest that they take time periodically to discuss ways in which the group could work together more effectively.

* Explain that each group should prepare a design for presentation during the next session, using models, posters, skits and/or other non-formal education techniques.

* Conclude by explaining that the group will eventually construct and evaluate their designs during this phase.

LIST OF QUALITIES OF FOOT-POWERED DEVICES

Type

Type of Motion

Speed

Power

Bicycle

Rotary

High

High

Treadle

Reciprocating

Medium

Medium

Kickwheel

Rotary

Low

Low

Chinese treadle

Rotary

Medium

Low

Weight shift

Reciprocating

Low

High

Treadmill

Rotary

Medium

Medium

Chinese pedal

Rotary

Low

High

Double treadle

Reciprocating

Medium

High

THE DESIGN PROCESS

I. Overview of the Whole Design Process


Figure A

II. A Closer Look at the Design Part

Establish criteria.

Be specific, for example:

 

It must be buildable in 20 hours.

 

It must weigh less than 25 pounds.

 

It must use only wood.

 

It must be built only with hand tools.

 

It must be usable by both sexes, etc.

Establish priorities of criteria


Figure B