. The miller, millwright and millfurnisher. orover shot wheels, with which, as experience has abundantly proved, aboutone-third of the power of the water is expended in simply obtaining velocity,or overcoming the inertia of matter. Turbine wheels require a less height ofstone foundation than other wheels. The overshot wheel splashes about,and causes rot unless the wood work is quite high; but there are cases whereit is not convenient to have the millstones above their splash level, as forinstance where it is desirable or necessary to have the stone floor near theroad level for teams. Overshot
. The miller, millwright and millfurnisher. orover shot wheels, with which, as experience has abundantly proved, aboutone-third of the power of the water is expended in simply obtaining velocity,or overcoming the inertia of matter. Turbine wheels require a less height ofstone foundation than other wheels. The overshot wheel splashes about,and causes rot unless the wood work is quite high; but there are cases whereit is not convenient to have the millstones above their splash level, as forinstance where it is desirable or necessary to have the stone floor near theroad level for teams. Overshot vs. Turbine.—Fig. 38 is intended to show why an over-shot wheel will not always yield the full power of the water. It shows anovershot wheel and the flume of a turbine to do the same work, the head andfall in both cases being 18 feet (a fair average). Of this it is customary to 84 TURBINES. allow 2 feet for head above the overshot, and 6 inches to prevent the wheelwading in tail water, limiting the diameter of the wheel to 15-^ feet. As. Fig. 39.—Overshot. the wheel begins to empty at some distance above the level of the waterin the tail race we may take off another foot of fall as lost, leaving 14-^ feet, OVERSHOT vs. TURBINE. 85 or only about 80 per cent, of the whole fall used. The turbine being at thebottom of the flume uses every inch of head and fall.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectflourmi, bookyear1882
