Water Wheel
A water wheel is a device that harnesses the energy of flowing or falling water to perform mechanical work. Traditionally used in various cultures, water wheels have played significant roles in agricultural and industrial applications, such as grinding grain, sawing wood, and generating electricity. They typically consist of a large wheel, often mounted on a vertical shaft, with blades or buckets that capture the water's energy.
Water wheels can be classified into several types, including overshot, undershot, and breastshot, depending on how water interacts with the wheel. The overshot wheel uses water from above, while the undershot wheel is driven by water flowing underneath it. In contrast, the breastshot wheel receives water at the level of the axle, optimizing efficiency based on the water's direction and energy.
While their use has declined with the advent of modern technology, water wheels continue to be appreciated for their historical significance and sustainable energy potential. They are often seen in heritage sites and eco-friendly projects, serving as a reminder of traditional engineering practices and the importance of renewable energy sources.
Subject Terms
Water Wheel
Since ancient times, people have used water wheels to power machines or to move water from one place to another. According to historians, water wheels were used by the ancient Romans as early as 1 BCE. In medieval Europe and elsewhere, water wheels were used to power mills and irrigate crops.
The town of Hama, Syria, is famous for its many giant water wheels, or norias ("wheels of pots"), which were used in conjunction with aqueducts as early as the fifth century CE to carry river water to farms and other towns. The design of the hydraulic turbine, which modern hydroelectric power plants use to generate electricity, is based on the principle of the water wheel.
What Is a Water Wheel?
In its simplest form, a water wheel consists of flat paddles, blades, or enclosed buckets mounted on a wheel, which turns on a central shaft, or axis. The wheel is moved by the force of water against the blades. As the wheel turns, power can be transferred through the shaft to another machine connected to the wheel, such as a mill.
The type of power generated by a water wheel is known as hydropower, or water power.
There are several different kinds of water wheels. The most common types are mounted vertically, on a horizontal shaft. An overshot vertical water wheel is powered by water that falls on the wheel from above, which moves the blades or paddles by the force of gravity. An undershot vertical water wheel is set in a fast-flowing river or stream; the water flows beneath it and strikes the paddles, causing them to move. If the wheel has buckets, these work to lift the water to a higher level.
Parts of a Water Wheel
Arms/Spokes: The arms or spokes of a water wheel run from the central shaft to the rims of the wheel.
Blades/Buckets/Paddles: The blades, buckets, or paddles are the parts of the water wheel that are struck by the falling or flowing water, which moves the wheel around. Blades and paddles are flat, while buckets are rounded and can hold water.
Rims: The rims are the large circular pieces connected to the spokes. The blades, buckets, or paddles are attached to the rims.
Shaft: The shaft is the axis on which a water wheel turns. As the wheel is turned by the flowing water, the shaft transfers the power being generated to perform work.
Bibliography
Brown, Jonathan. Water Power and Watermills: An Historical Guide. Crowood Press, 2011.
Reynolds, Terry S. Stronger Than a Hundred Men: A History of the Vertical Water Wheel. 1983. Johns Hopkins UP, 2002.
"The Water Wheels of Hama." National Museum of Denmark, en.natmus.dk/historical-knowledge/historical-knowledge-the-world/the-lands-of-the-mediterranean/the-far-east/digital-hama-a-window-on-syrias-past/the-water-wheels-of-hama/. Accessed 19 Oct. 2017.
Wikander, Örjan. "Sources of Energy and Exploitation of Power." The Oxford Handbook of Engineering and Technology in the Classical World, edited by John Peter Oleson, Oxford UP, 2008, pp. 136–57.
Yorke, Stan. Windmills and Waterwheels Explained: Machines That Fed the Nation. Countryside Books, 2006.