Wally Minto's eyes twinkled. "Now that you've got your pictures of the serious stuff, I want to show you our latest engine. It's at least 85% effecient, never wears out, requires no fuel or maintenance, costs very little, and should have been invented 100 years ago."

I'd just finished shooting pictures os Minto's solar-powered, Freon engine/generator set (P.S. Feb 1976) and I wasn't quite sure if he was kidding about this newest engine. Four used propane bottles were hose-clamped to the ends of two pieces of aluminum angle, each about four feet long. The angles crossed at 90 degrees at the center and were mounted on a central hub like a skinny four-blade windmill with bottles to swing in the breeze. Each bottle was connected to its mate on the opposite end of the angle with steel brake-line tubing. Under the rig's support was a tank of the type used to locate leaks in an inner tube.

While I gazed in disbelief, Wally explained how his incredible power wheel works (see diagram above) [text is included at the end of this file].

A few weeks later I again visited the Kinetics lab. By then the propane bottles had evolved into 12 containers of steel pipe welded into a polygon. The principle remained the same. I watched as Wally opened the valve to let in a trickle of water from solar panels on the roof of his parking shed. The water temperature was 155 degrees F.

Almost imperceptibly, the wheel started to turn. The speed picked up a bit and I timed a revolution -- about one rpm. Minto noted my misgivings. "Try holding onto the shaft," he said. I grabbed the shaft firmly -- it was if I'd tried to stop some eerie, irresistible force: no sound, no evidence of power, just pure twist.

"Picture one 200 feet in diameter," he said. This time my mind boggled. Such a rig might hoist the pyramids.

Wally doesn't expect industrialized nations to scramble for his wheel, and he isn't selling anything. He's donating it as a "gift to the world" and expects it will be used in underdeveloped, energy short areas.

For example, a practical 33 ft. diameter wheel running on a temperature difference of as little as 3.5 degrees F and producing several horsepower could pump irrigation water, grind grain, or saw wood. The materials could be scrap pipe, and no machining or skills are needed to build it. Several low-boiling materials might be used, but propane or R-12 may be best.

Minto estimates a slightly larger (40 ft.) wheel with 14 pairs of one-ft. by 4.5 ft. containers would provide 10,240 ft/lb of work per container as each 269 lb of liquid responds to gravity through a 20 ft level arm. At only one rpm this is 8.69 hp; not spectacular, but low cost and capable of running steadily for generations. The slow rotational speed can be stepped up to whatever is needed, just as with the old-time waterwheels.

No fuel would be needed in many cases. The temperature difference required between the liquid on the bottom and the top occurs naturally in many situations: water and air, light and shade, etc.

Minto has outlined construction details in a two-sheet paper entitled "The Minto Wheel." There are no restrictions on building or experimenting with the wheel.

Sun Power Systems, Inc.
1121 Lewis Ave.
Sarasota, Fla 33577

[graphic 1, not available]

Polygon wonder wheel is made of individual containers. (Almost any leakproof container can be used.) Tubes connect opposite pairs. I wasn't sure it would run. It runs! Minto demonstrates wheel's torque; simple pony brake on output wheel measures hp. Speed is about one rpm, but torque is strong.

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[graphic 2 not available]

Low-boiling liquid, such as freon or propane, fills one bottle of each pair. The opposite bottle is empty and void of air. The liquid collects in the lower bottle, which is immersed in warm (solar-heated) water. Heat from the water (or a solar reflector, or any other source slightly warmer than the surrounding air) vaporizes the liquid and forces part of it up through the connecting tube and into the empty bottle on top. Gravity does the rest: The heavy bottle starts down; the lighter bottle floats up. As each pair shuttles its liquid mass back and forth, the whole thing turns and repeats the process endlessly.

LINKS

• Mother Earth News tests minto wheel
• Minto's Wheel & email response (from Solaris)