Reply #5: Oh! An "Undershot" wheel [View All]

[OKIsItJustMe]

http://en.wikipedia.org/wiki/Water_wheel#Undershot_wheel

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Undershot wheel

A undershot wheel (also called stream wheel) is a vertically-mounted water wheel that is rotated by water striking paddles or blades at the bottom of the wheel. The name undershot comes from this striking at the bottom of the wheel. This type of waterwheel is the oldest type of wheel. It is also regarded as the least efficient type, although subtypes of this waterwheel (eg the Poncelet wheel, Sagebien wheel and Zuppinger wheel) allow somewhat greater efficiencies than the traditional undershot wheels. The advantages are that is somewhat cheaper and simpler to build, and they are also have a less great environmental impact as they do not constitute a major change of the river. The disadvantages are as mentioned before the smaller effciency, which means that they generate less power and can only be used where the flow rate is sufficient to provide torque.

Undershot wheels gain no advantage from head. They are most suited to shallow streams in flat country.

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