Windpump

A windpump is a wind-driven device which is used for pumping water.

Windpumps were used to pump water since at least the 9th century in what is now Afghanistan, Iran and Pakistan.^[1] The use of wind pumps became widespread across the Muslim world and later spread to China and India.^[2] Windmills were later used extensively in Europe, particularly in the Netherlands and the East Anglia area of Great Britain, from the late Middle Ages onwards, to drain land for agricultural or building purposes.

Simon Stevin's work in the waterstaet involved improvements to the sluices and spillways to control flooding. Windmills were already in use to pump the water out, but in Van de Molens (On mills), he suggested improvements, including the idea that the wheels should move slowly, and a better system for meshing of the gear teeth. These improvements increased the efficiency of the windmills used to pump water out of the polders by three times. He received a patent on his innovation in 1586.^[3]

Eight- to ten-bladed windmills were used in the Region of Murcia, Spain, to raise water for irrigation purposes.^[4] The drive from the windmill's rotor was led down through the tower and back out through the wall to turn a large wheel known as a noria. The noria supported a bucket chain which dangled down into the well. The buckets were traditionally made of wood or clay. These windmills remained in use until the 1950s, and many of the towers are still standing.

Early immigrants to the New World brought with them the technology of windmills from Europe.^[5] On US farms, particularly on the Great Plains, wind pumps were used to pump water from farm wells for cattle. In California and some other states, the windmill was part of a self-contained domestic water system, including a hand-dug well and a redwood water tower supporting a redwood tank and enclosed by redwood siding (tankhouse). The self-regulating farm wind pump was invented by Daniel Halladay in 1854.^[5][6] Eventually, steel blades and steel towers replaced wooden construction, and at their peak in 1930, an estimated 600,000 units were in use, with capacity equivalent to 150 megawatts.^[7] Very large lighter wind pumps in Australia directly crank the pump with the rotor of the windmill. Extra back gearing between small rotors for high wind areas and the pump crank prevents trying to push the pump rods down on the downstroke faster than they can fall by gravity. Otherwise pumping too fast leads to the pump rods buckling, making the seal of the stuffing box leak and wearing through the wall of the rising main (UK) or the drop-pipe (US) so all output is lost.

The multi-bladed wind pump or wind turbine atop a lattice tower made of wood or steel hence became, for many years, a fixture of the landscape throughout rural America.^[8] These mills, made by a variety of manufacturers, featured many blades so that they would turn slowly with considerable torque in moderate winds and be self-regulating in high winds. A tower-top gearbox and crankshaft converted the rotary motion into reciprocating strokes carried downward through a rod to the pump cylinder below. Today, rising energy costs and improved pumping technology are increasing interest in the use of this once declining technology.