The above image is my first concept of a "Minto's Wheel". I have gotten many e-mails regarding this project. I have done some more research on this concept and found that a German clock company came up with a similar concept in the 1940s, so Wally Minto's idea my not be his unique idea. See the picture below. This is definitely on my list of future projects, and something I think about often. I have several revisions in mind since the above concept. If you are interested in a "Minto's Wheel" I suggest that you check out this site http://www.keelynet.com/minto/minto2.htm for more information. Please note in their first drawings that the heat source is applied after center. This is necessary to have a self starting machine. The need to offset the heat source is also noted in issue #40 of Mother Earth News "Mother's Minto Wheel: A Report".
Below is my latest concept. It is based on a 20 inch BMX bicycle rim with six soldered copper tubes. I intend to pull a vacuum in each tube and then allow that pressure difference to draw the working fluid into three of them. When I connect the other three and open the valves, the pressure will equalize and still be below atmosheric pressure. This should decrease the vapor pressure and allow the fluid to vaporize at a lower temperature. I will first try some "white" gas. If that is not sucessful, then I'll try some Acetone. As you can see, I tried to utilize standard components. The plan is to spray or flow heated water (solar) over the canister/s in the lower right area having the pan catch dripping water, this heated water causing the fluid in the immersed canister to expand, forcing the fluid into the upper canister. Gravity then drags the heavier canisters down, turning the wheel. The canisters "cool" when they are not exposed to the heated water. The long moment arm and large canisters should provide a large operating torque. Since this operates at a very low RPM, I would recommend a very large pulley to drive an electric generator. The water in the collection pan could be heated with a solar collector or by burning waste motor oil. I hope to begin work on this project sometime soon.
Here is a cut away of the heat exchanger that I'm going to use in my solar collector. I've used a 3/4 by 1/2 reducing "T" to hold 1/2 inch copper pipe concentric with a piece of 3/4 inch copper pipe. I've soldered a piece of 14 ga. copper wire wrapped around the 1/2 inch pipe to swirl the water. The heat exchanger will have a reducing "T" at both ends. At one end the water will be looped around from center to outside pipe. This heat exchanger will be mounted at the focal point of a 4' x 8' tracking parabolic reflector. The 3/4 inch pipe will be painted flat black. I'll post more details as they become available.