How A Water Pumping Windmill Works


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Categories: Hydro Power

Standing tall like a giant sunflower in a sea of undulating prairie grasses, or in any rural setting, a windmill is a thing of beauty. Not only are water pumping windmills a joy to watch, but they are incredibly useful. Powered only by wind, they work like quietly-purring nonpolluting creatures, to keep our storage tanks overflowing with fresh water. They operate effortlessly, efficiently, reliably.

History of the windmill

Windmills have been around since the Middle Ages. The first recorded evidence of windmills being used for pumping water and grinding grain was in 7 AD in Persia. Then China got ahold of the idea and it spread to Asia, Africa, and the Mediterranean. The European mill appears to have developed independently from the others because the design is so different. The predecessor to our modern windmill dates back to France in 1105 and England in 1180. In the 14th century, the Dutch took windmills to a whole new level with their "tower" mills using canvas sails stretched across four wooden lattice frames like a big X. Their objective was moving enormous amounts of water into higher basins and canals. By the end of the 16th century thousands of windmills were pumping and grinding in western Europe. By the late 19th century, the count was 30,000—and, miraculously, there was still enough wind to go around.

Detail of a windmill pump rod assembly

The American windmill

The American multi-bladed windmill bears little resemblance to its European counterpart. Unlike the Dutch "scoop" mills that could move 16,000 gallons an hour but only lift it 16 feet, the new Yankee design could lift water from hundreds of feet below the surface. It was invented in Connecticut in 1854 by a young mechanic named Daniel Halladay. Its wheel, made from wooden "sails," could be transported in sections and assembled on location.

He ingeniously designed the wheel to automatically turn its face into the wind by wind pressure on the vertical tail behind it. If it got to spinning too fast, a weighted mechanism came into play that turned the wheel partially out of the wind to slow it down.

Halladay sold thousands of his machines, and before long there were 300 competing manufacturers producing similar wooden-bladed beauties. Then in 1886, Thomas Perry designed the more aerodynamic steel-bladed windmill, with curved blades (to catch more wind) and that design is still used today.

The windmill pump cylinder. Each up-stroke (figure on right) pulls a certain amount of water into the cylinder, but on the down-stroke (left) a check valve in the bottom won't let it be pushed out, so the water has nowhere to go but up with the next upstroke.

In the late 1880s and early 1900s, windmills were sprinkled all over the American landscape. They were indispensable to the late-comer settlers who were forced to move farther west to the sun-parched remote plains, after all the more desirable spots near rivers and streams had been taken. In the Great Plains and the vast territory known as the Great American Desert, water was more precious than gold.

Windmills were also indispensable during the construction of the railroads to provide drinking water for the crews and to supply water for the steam locomotives. Workers erected a windmill and an adjacent storage tank every three miles along the tracks. Some of the railroad mills were 30 feet or more in diameter.

That entire chapter of history is written in the wind, the wind that powered those windmills. There would have been no life, hence no progress, without water.

Windmills were once status symbols. In 1910, a farmer or rancher who could afford the best Sears & Roebuck "Kenwood Back-Geared Galvanized Steel Pumping Model" with red painted tips on the vanes and tail ($25) had something to crow about. Poorer homesteaders had to make their own mill heads and towers out of wood.

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