A farm windmill harnesses wind energy, primarily for pumping water. This technology has a history spanning many centuries. Originating in regions of Afghanistan, Iran, and Pakistan by the 9th century, wind-powered machines spread globally, becoming particularly significant in the American agricultural landscape by the late 19th and early 20th centuries. Farm windmills provided a means for homesteaders and ranchers to access water from wells, reducing reliance on natural surface water sources.
Core Components
The visible part of a farm windmill is its multi-bladed rotor, composed of galvanized steel blades that capture wind energy. The blades are curved to efficiently convert wind into rotational motion, with some designs having around 18 blades for effective water pumping. Positioned behind the rotor, a tail fin orients the windmill head into the prevailing wind, ensuring maximum efficiency. This fin also provides a safety mechanism, allowing the rotor to “furl” or turn out of excessive wind speeds to prevent damage during high gusts.
Below the rotor, a gearbox translates the horizontal rotational movement of the blades into the vertical reciprocating motion for pumping. This mechanism converts the slow rotation of the wind wheel into the up-and-down action of the pump rod. A tall steel tower supports these components, elevating the mechanism to a height where wind speeds are stronger and more consistent, minimizing interference from ground-level obstructions. Extending down from the gearbox into the well is a long pump rod, the direct link to the water-lifting mechanism below ground.
From Wind to Work
Wind flows across the windmill’s specially shaped blades. Similar to an airplane wing, the curved design of the blades creates a pressure difference, resulting in aerodynamic lift that causes the rotor to spin. This rotational energy transfers through a main shaft to the gearbox. Inside the gearbox, gears and a pitman arm work together. This arrangement converts the continuous rotary motion of the wind wheel into the vertical, linear, up-and-down stroke for the pump rod.
The pump rod extends deep into the well, connecting to a plunger within a pump cylinder submerged below the water level; as it moves upward, the plunger creates suction, drawing water into the cylinder past a one-way check valve at the bottom. When the pump rod descends, this bottom check valve closes, and a valve within the plunger itself opens, allowing the water to move above the plunger. With the next upward stroke, the water trapped above the plunger is forced higher into the drop pipe, eventually reaching the surface. This cyclical action, driven by the wind’s energy, provides a continuous flow of water. The multi-bladed design of farm windmills generates the high torque needed to initiate and sustain pumping, even in lighter winds.
Farm Windmill Applications
The primary application of farm windmills is pumping water from wells or surface sources for various agricultural needs. This includes providing drinking water for livestock, filling troughs and ponds in remote pastures. Windmills are also used for irrigation, delivering water to crops, especially in areas where consistent rainfall is not guaranteed. They offer a reliable and independent solution for water supply, particularly in off-grid locations where access to electricity is limited or unavailable.
Beyond water pumping, farm windmills have historically been used for tasks like grinding grain or powering sawmills, though water pumping remains their most common application. The ability of these systems to operate without external power sources makes them a sustainable choice for remote farming operations. By providing consistent water access, farm windmills support efficient land use and livestock management.