. The miller, millwright and millfurnisher. 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 Fig. 40.—TiRBiNE. Figs. 39 and 40 are intended to show the advantage of a turbine, forhigh falls, over an overshot wheel. The overshot shown is of 22 feet diam- 86 TURBINES. eter by 3 feet face, to work under 24 feet head and fal
. The miller, millwright and millfurnisher. 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 Fig. 40.—TiRBiNE. Figs. 39 and 40 are intended to show the advantage of a turbine, forhigh falls, over an overshot wheel. The overshot shown is of 22 feet diam- 86 TURBINES. eter by 3 feet face, to work under 24 feet head and fall. The bevel wheel Bis 12 feet diameter; spur wheel D is 9 feet. The upright, running only 20turns per minute, must be very heavy—in this case 8 inches in shaft H must be at least 4 inches in diameter. It will be seen that all ofthe parts are very heavy and that friction is necessarily very great; while thecost is excessive. The other cut shows an ii-^-inch turbine, which will givemore power than the 22-foot overshot. Instead of the 2-foot shaft of theovershot, or an iron shaft of 10 inches, there is simply a i;|-inch wrought-ironshaft; while there is needed only a lo-inch iron pulley weighing 30 pounds,from which the belt runs directly to the buhrs. Instead of the 4 to 8 inchshaft H, there is a light i-^-inch shaft. Instead of gearing up for
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectflourmi, bookyear1882
