This lesson is focused on using a bicycle to pump water. Along the way, students will learn about rotational speed, torque, and rotational power, as well as something about how pumps work. Once they're done with the lesson the pump doesn't have to be powered by a bicycle: the drive-train made for the bicycle will work just as well for a wind-turbine.

If there's a broken electric pump students can use, great! If not, they should make their own pump; see the 'Piston Pump' lesson for an example.

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Torque, rotational power, rotational speed, belts & pulleys, measuring/estimating power, matching power source to load requirements.

Technical skills taught will depend on how the students make to power the pump with the bicycle.

The students have a task: power a pump with a bicycle. They have a pump. They have a bicycle. Armed with knowledge of belts and pulleys, they have to design the drivetrain.

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A bicycle-powered pump.

PEN lessons that meet the requirement are noted in brackets.

Basic maths and physics; I'm thinking, thought I'm not sure, that one can measure their weight, and then change the bike's gearing or the pulley ratio until they're just standing on the pedals with their weight: this could give an estimation of the power requirements of the pump. Or maybe it won't work at all.

They'll be designing and making a pulley system, so they should be comfortable considering various ways to hold them in place, and then making them fairly precisely and rigidly.

Savonius turbine (for an automatic pump), or a waterwheel

The teacher could demonstrate the effect of different gear ratios on a flipped-over bicycle.

Students will measure how much power the pump uses, and determine what speed they want it to operate at.

Students will need the materials below, and a setting where they can experiment with different mounts, and a place where their pump can be set up.

Designing the system that transfers power from the bike to the pump (hereafter called the 'drivetrain') will be a challenge that depends on available resources. If students can slip a pulley around an electric pump's drive shaft, the problem becomes mainly one of maths: determining the right pulley ratios to make the work pleasant and possible, then making the pulleys (if necessary) and mounting them.

It's worth noting here that it's not strictly necessary to use pulleys: bike gears and chains will work as well, especially if you can weld them to pieces that fit the appropriate driveshaft.

If, on the other hand, students have made their own pump, they may have to design their own rotationally-powered interface to drive it. On the other hand, they may be able to design the pump in a way that simplifies the drivetrain.

All of these projects will probably require a bike-stand, which could serve as a warm-up project for the design and making of rigid structures.

Of course, all these design projects should follow the cycle: brainstorm multiple options, evaluate them, build a prototype (or devise an experiment), and then restart the cycle.

Bicycle parts.

Scaffolding material for holding the pulleys–needs to be pretty rigid, so welded tube and reinforced wood are both good options.

None–that's the point of using student's weight as the force measurement.

Pen and paper and a scale to calculate power with.

4 to 6 students, ideally comfortable with building and designing rigid wooden or metal structures to a fair degree of precision.

Why should students want to participate in this lesson?

Pumps are useful and necessary: pumping water can be an arduous task if it's for your home, or a time-consuming one if it's for your fields. Pumps are fragile, and hand-pumps often break because of misuse.

Why should teachers want to teach it?

It's a nifty project with an appreciable communal benefit. If someone got good at making these, it's not hard to imagine them making a living doing that (especially if they're wind-powered).

If this lesson (and its prerequisites) were the only PEN lessons someone took, what should they be able to do?

See above.

If you had to teach this lesson tomorrow morning, what would you spend tonight working on? (assuming that materials were not an issue)

Structure the lesson: E.g., first talk about mechanical power, then demonstrate on a bike, then talk about connecting to the pump, then everyone makes some example pulley setups…etc.

If you hadn’t taught this lesson before, what questions would you have for someone who had taught a very similar lesson?

What bottlenecks did students run into while designing and building the connection system?

Was it easy to use a broken electric pump? How do electric pumps usually break?

Did it work to have students compare the power they put into the pump by using their different weights? Did you get a useful number that allowed you to change the pulley ratio knowledgeably?

If the only materials available were broken radios, TVs, and computers, could you do all the electronics in this lesson? (assuming you had solder, soldering irons, etc.) If not, what would be missing?

There are no electronics in this lesson except for a working scale. Which doesn't even have to be electronic, technically.

If the only structural materials available were dish-cloths, cardboard, and plastic bags, could you make the mechanical bits of this lesson? (assume equipment as above) If not, what would be missing?

Bicycle parts are common in many places throughout the world were other precision parts are not available, but even with those added to the list this would not be enough.