Airlift Pump Powered Waterwheel Winch! Alternative to Small Electric Motors for Low Tech Settings.

The waterwheel winch is a very low tech DIY alternative to electric motors for certain situations. My version uses an airlift pump to move the water to turn the waterwheel. Other ways to supply the water are possible. I use clamping a rubber tube that supplies air to the airlift pump to turn on and off the waterwheel and to adjust its speed. I use the waterwheel winch to rotate a solar cooker reflector to track the sun. The reflector is on "equatorial mount" so if you point it at the sun in the morning, and rotate it at 15 degrees per hour for the rest of the day, it will remain pointing at the sun all day. The waterwheel winch is able to do task with ease!

I used a table saw and a mitre saw to do the cutting and a battery drill and impact driver to put the pieces together. A waste piece of plywood became the wooden disk of the waterwheel and I used a packet of plastic cups from the dollar store for the "buckets of the waterwheel. Short wood screws were used to hold the cups in place. A second hand oscillating fan was used as the axel of the waterwheel and as the winch part.

I was already using an airlift pump to move water from one container to another to rotate my solar panel. Lowering water in one container lowered a float, as the water was airlifted to another container, the float in that container raised up. String attached to the floats rotated the solar cooker reflector. It worked well but it is big and bulky. My solar cooker was heavier than the solar panel, so I used a bigger system, that had a 50 gallon barrel and another half barrel with a huge float in it. This was huge!. I checked around on the internet and maybe I could adapt Daniel Connell's "sunflower" idea to do the rotating. His "waterwheel" was totally different from what I had in mind, but I thought that I could use the parts of a reciprocating fan to achieve something similar. They have an internal worm drive which acts for gear reduction and is part of the bit that continuously turns the fan left and right. Worm drives are nice because they only allows for energy transfer in one direction. In this case, you can turn the fan blades to move the worm drive, but you cannot turn the worm drive to move the fan blades. I bought about 5 old second hand fans and took them apart. All had cheap plastic worm drives. It wasn't going to work because sometimes it gets windy and this puts a lot of stress on tiny gears. I would have to think of something else!

Well, I can use the fan as an axle for the waterwheel. The next issue was what to use as "buckets" and how to attach them. I decided on plastic cups from the dollar store. I was going to attach them upright, but there were issues, How could I get a leak proof attachment? Just seemed to be messy. Also, you can put water in them up at the top, but it all falls out after a quarter turn of the wheel. (See the diagram) I couldn't see this working well! Then I thought of putting them lying down. I bought 3 different sizes from the dollar store before I hit on the right size for my wheel. Turns out you need only one attachment point, at the top of the cup, and they are snugly pushed into the previous cup as you attach them. It was way more sturdy than I expected!

I determined that the waterwheel needed to lift 4kg to turn my solar reflector. (I used a fish weigher and pulled the solar cooker with it, (it needed at most 4kg of pull to move it). So I attached a string to the axle of the waterwheel at the other side of the fan, attached an 11 pound weight (5 kg) to the string, poured water on the waterwheel from the fan and it lifted (winched up) the weight with ease! Not only that, the buckets of the waterwheel didn't get full so that means there was plenty of capacity in the tank to lift a heavier weight! Another great feature is that the waterwheel "locks in place" The water in the buckets weighs enough to balance the weight of whatever it is lifting or pulling. It takes considerably more weight to pull it back down because the water in the buckets have to be moved away from underneath the center of the waterwheel first.

In this case, it was a winch with one string being unwound away and another being winched towards the wheel. This is because the reflector had to be moved fairly accurately to a position and stay there. The airlift pump provided water to near the top of the waterwheel as required. It worked really well! At least at the start. ........ But over time the string stretched. This allowed "play". The reflector could rock back and forth in the wind. Having something to tension the string wasn't really a solution, because it would still allow "play" just at a different wind speed,

I tested the Waterwheel winch for about a month and a problem became apparent. Over time the string stretched. I was using cheap thin string so it stretched a fair amount. This is a problem because when the string is loose, the reflector can get caught by the wind and accelerated, building up power until it meets resistance. And a gusty wind can whip it back and forth. This means that sometimes the waterwheel can't hold it in place. But when I looked into it, even the best string and rope stretches a bit. What could I do?

Back on the internet to do research, i found a neat video from a robotics guy about his experiments with capstan drives for robots. So all I needed to do was detach the release string, lap it a few times around the axle, and attach it to a 1 kg weight! This meant that there was always good tension on the strings, and the wind had to be much stronger to catch the reflector and spin everything.

The waterwheel winch is a bit like a slow motor that doesn't use electricity or a gearbox and will never burn out! My air pump is on a timer that can be set for 15 minute on off intervals. So you could use a waterwheel winch for as little as 15 minutes a day. As long as you can get low pressure air to the area, you can install a waterwheel winch there.

Compost Tumblers! With the right gearing, the waterwheel can slowly tumble your compost! The tumbling can be so slow that worms can avoid getting crushed but aeration would still be very good.

Greenhouse night curtain. Turn on the air and run the winch for a few minutes in the morning and at night to open and close the curtains.

There will be issues in winter in frosty areas, but I think it has potential to move night curtains in small greenhouses. That was my original thought. It might be used in kinetic sculptures. I have "always on" compressed air from a little bubble pump for my fish tank, so I have lightly compressed air all the time so airlift pumps are easy for me. Some others might want to use a little electric water pump instead. As long as it lifts water about 2 ft 60 cm, you should be good to go with your waterwheel.

I think the waterwheel winch is a cool thing, but it could be better.

WISHLIST

ONE . I wish I knew how to get a small solar panel and photo diodes to control the air valve that turn the waterwheel on and off. Or something like the little motor with a small gear in the attached diagram. The part that currently controls the air valve is all analogue and time based at the moment.

TWO. Check the attached waterwheel diagram. If I make holes in the plastic cups near the top and to the side, then I can add the water one higher on the wheel. If it goes into the yellow bucket currently, it will drip out onto the waterwheel. But if I go across level with that spot and a little bit down and go about half way to the other side, And put a hole in, that means I can fill the yellow bucket up to that hole and it will fill to that level and drip down into the next bucket. this will give the whole thing more torque!

THREE There is probably a much better way of doing the buckets. And probably something better than plastic cups to do it. I just haven't thought of it yet.

FOUR My waterwheel winch only provides power in one direction. It would be really nice if it could work both forwards and reverse.