This summer I made a bunch of fun things out of PVC for my visiting nieces and nephews, and this wind-powered water pump is a combination of two of those projects: a wind-powered deer deterrent, and a pump-style water gun.
This water pump is definitely in beta stage. All the components work, but the design is highly inefficient and requires considerable wind to pump water out of our pond. In the video below I act out the part of a gale to give you a visual of how the pump works. The last step in this instructable will discuss the bugs in the current design and how they can be improved for a more efficient use of wind power.
SEE FINAL STEP FOR A COMPLETE RE-DESIGN AND VIDEO OF WORKING PUMP.

Step 1: Wheels and Gears

Like my outdoor chandelier project, most of the parts for this wind pump came from the bicycle shop dumpster. I don't know the names for all these parts, so I'm not naming them. What I can say is that the gear-looking pieces were not gears on the bikes (I turned them into gears by adding bolts). I found them on mountain bike wheels, and they can only be installed on a wheel that had one in the first place.
I'm also not sure what the best order is for putting this wind pump together, so I'll just rattle off what I did.
1. Added small bolts into every other hole in one of the "gears." For the top (horizontal) gear I used shorter bolts; longer ones for the vertical one. I left the top bolts as is and put nylon spacers over the vertical gear "teeth," securing them with Teflon tape.
2. Attached the horizontal gear to the axle of a mountain bicycle wheel.
3. Attached a second bicycle wheel rim to the first using three metal brackets (mine ended up shorter than shown in this picture due to a change in plans).
4. Found a way to secure a 1" PVC tee to the top of a tripod.
5. Installed the bicycle wheel contraption into the top of the PVC tee. I used a couple wooden circular pieces drilled out of a piece of 1x2. The hole in the center of the wooden pieces held the axle rod firmly in place. I used a couple odd pieces as spacers to elevate the horizontal gear to the spot where it would catch the vertical gear.
6. Installed the vertical gear into the horizontal part of the PVC. The gear must sit on a ball bearing so it can rotate freely. I used part of an axle that had a bearing inside. Use whatever you can find to "stuff" the gear into place and keep it from wobbling.

I had to do a lot of shimming and shaving to get things to fit. I shimmed with toilet paper cardboard and shaved with a dremmel or sandpaper. You do what you gotta do.

Step 2: Making the Wind Foils

I wanted the wind foils to be bigger than the ones I installed on the deer deterrent gizmo, but still light. Tin seemed like the perfect material, but I was afraid of getting all cut up when I tried to cut the tin pieces to size (I grabbed a piece of duct from a recycle yard for the purpose). So I painstakingly felted five pieces of silk and coated them with polyurethane. They turned out stunning, but when I installed them and set the windmill out for a test, they were a complete dud. The wind didn't know what to do with all that fluff. These plastic +silk foils are my quick substitute for the felted ones.
I don't know what this plastic is called. I was using it as a light diffuser in photography, as it's semi-opaque and lightweight. Hopefully someone will know what it's called and where to buy it.
For the foils, I divided what I had into five. I wanted the largest possible foils, given what I had to work with. Then I bought a silk scarf at a thrift store and cut that into five (a little bigger than the foils).
I sanded the dull side of the plastic and painted it with polyurethane for adhesive (because that's what I had on hand).
After gluing the silk to the plastic sheets, I trimmed off the excess silk and punched holes for the spokes that would hold them to the bicycle wheel rims.

Step 3: Installing the Wind Foils

To install the wind foils, I drilled five holes big enough to fit a bicycle spoke into--in both bicycle wheel rims. The spokes are inserted from the inside of the rim and secured with plumber's epoxy. Once the epoxy dries, the foils are slipped onto the spokes and secured to the outside of the spokes with epoxy. I screwed spoke nuts onto the end of the spokes to keep the foils from falling off.

Step 4: The Wind-Pump Connector

If you look closely at the vertical gear mechanism, you'll see a small red ball bearing on the back side of one of the gear "teeth." This bearing, and another identical one attached to the piston on the water pump are what allow the connecting piece between the windmill and the water pump to move freely, transferring the wind's horizontal force into the up-and-down force of the water pump. The connecting "rod" itself is made out of PVC. I painted it to look rusty (see step 4 in the the outdoor chandelier project for details), and later inserted some bicycle spoke nuts into the plastic by heating them over a gas stove.

Step 5: PVC Water Pump

Here is the drawing of the PVC water pump gun I made for my visitors. I made no changes except to add an eye hook to the top of the piston and secure the second ball bearing to the hook.
And here also is the video of how I put it together.

Step 6: Assembling the Wind-Powered Water Pump

To assemble the wind-powered water pump, I hammered a metal rod into the ground where I wanted the pump to stand. To this rod I braced the outer part of the pump mechanism using two screw clamps. Then I positioned the windmill part of the whole thing centered above the pump and high enough to allow the connecting arm to extend and contract without buckling. Lastly, I attached the connecting arm to the two ball bearings--one on the horizontal gear, the other on the pump piston.
The project is complete. It really is a thing of beauty...

Step 7: Bug Report

The biggest problem with this wind-powered water pump design is that every single part of the assembly is a bit wobbly, and all the wobble eats up a lot of the wind energy that should instead go into pumping water. To solve this problem in the next version, I would:
1. Use a sturdier tripod.
2. Use a bicycle rim that isn't warped. The bottom rim in this project is badly bent from some bike accident, and the motion it makes wastes wind energy.
3. Use tin or PVC for the wind foils and attach them directly to the bicycle wheel rims. My deer deterrent has smaller foils, but they are more efficient than the ones on this water pump system. A lot of wind energy is lost with the shaking of the bicycle spokes.
4. Use a heavier rod driven into the ground to hold the water pump. Or install the whole thing onto a 4x4 post to eliminate unwanted movement (again, like my deer deterrent).
5. Make all parts as light as possible--especially the connecting arm between the gear and the pump piston. The more weight the gear has to lift, the more wind will be required to lift it.
6. Find a better solution for the gasket part of the piston. The harder it is to push and pull the piston, the more wind energy is needed to pump water. I used 3M oil to lubricate the rubber part of the plunger, but I think mine isn't as efficient as it could be.

Any solutions to the above would be appreciated.

Step 8: WORKING Water Pump From Bicycle Parts

Here is the final redesign of the wind pump including many of the suggestions made by readers (thank you!).
Let's see if I can list them:
* Substituted a single hollow metal pipe for the backbone of the entire wind turbine/pump system (was a tripod before).
* Lowered the valve system to the ground so the pump wouldn't have to raise the water as far.
* Removed the nylon tip from the outlet end to reduce pressure requirement.
* Changed out the PVC piston for a bicycle shock (after removing the spring and sawing off the tip).
* Changed out the PVC arm for the inner part of a bicycle shock.
* Inserted CDs at a 45 degree angle into the top bicycle rim (not sure this had much effect)
* Reduced wind drag on the sails by unhooking the lower part of each sail from the bottom spoke while leaving the spoke in place to hold the sail in "attack mode" yet allow it to swing out of the way in "drag mode." This was the SINGLE MOST EFFECTIVE change to the wind pump!
Thank you everyone for you input!