An Undershot Water Wheel

By Richard N. Mccray
Published on July 1, 1983
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To withstand the force of high water, the wheel is mounted to a swinging carriage, which in turn is suspended from a pipe framework partly supported by a diagonal guy wire.
To withstand the force of high water, the wheel is mounted to a swinging carriage, which in turn is suspended from a pipe framework partly supported by a diagonal guy wire.
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The PVC-pipe pump mounted to its swivel bracket. The intake hose with its foot valve is on the left, and the T's right arm delivers pressurized water.
The PVC-pipe pump mounted to its swivel bracket. The intake hose with its foot valve is on the left, and the T's right arm delivers pressurized water.
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Once the ideal size and shape of the paddles were established, a sheet-aluminum template was used to assure consistency.
Once the ideal size and shape of the paddles were established, a sheet-aluminum template was used to assure consistency.
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The paddles were mounted to the iron wheel with U-bolts and small aluminum bridges.
The paddles were mounted to the iron wheel with U-bolts and small aluminum bridges.
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This unassuming creek supplies the power for the wheel, and water for the garden.
This unassuming creek supplies the power for the wheel, and water for the garden.
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The complete water wheel parts and assembly diagram.
The complete water wheel parts and assembly diagram.
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The author tightens the end collar on the completed wheel's axle shaft. The hub, crank, and axle assembly all spin as one within two oaken bearings.
The author tightens the end collar on the completed wheel's axle shaft. The hub, crank, and axle assembly all spin as one within two oaken bearings.

I got my first taste of water wheels at the age of five, when my great-grandfather McDowell made me a toy paddle turbine to run under the spring-fed spigot at the back of the house. Today, some 65 years later, I’ve applied the principles of that early lesson to building a full-sized undershot water wheel that provides me with every drop of water I need to supply my thirsty garden throughout the entire growing season.

My vegetable plot, you see, is quite a distance from the house and its plumbing. True, the garden is located not far from a small perennial mountain stream that forms the southern boundary of our property, but that “crick” runs a good 8 feet or so below my patch!

Now I certainly don’t have an aversion to honest work, but the drudgery of using a hand pump to fill a washtub, lugging the sloshing vessel around, and repeating this operation at least six times every time I wanted to water my garden forced me to look for a less labor-intensive means of getting the job done. Naturally, that first water wheel in my life came to mind, so I set about researching the design and operation of functional “paddle pumps” in hopes of building one at my site that’d handle my watering chores with a minimum of maintenance.

Planning the Water Wheel

Because there was only about 4 inches of fall in the part of the stream bordering our land, an overshot wheel was out of the question. Unfortunately, I had little luck digging up specific information on undershot water wheels, so I had to use common sense–and a by-guess-and-by-golly approach–to make my project a success.

Early in the game I decided that an all-wood wheel would be too expensive and time-consuming to assemble. So, considering the fact that an undershot design uses paddles rather than the intricate buckets of an overshot apparatus, I figured I’d search for a metal-spoked wheel about 4′ or 5′ in diameter and simply fasten some plywood paddles with 1′-square blades to it.

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