Scoop-wheel.
A form of the tympanam water-wheel in which the buckets are so curved as to scoop up the water into which they dip, raising a portion of the same and conducting it toward or into the axis, where it is discharged. See tympanum. Another form of the scoop-wheel is also adapted to raise water to an elevation equal to about half the diameter of the wheel, but delivers it at the periphery, instead of near the axis. Some of the scoop-wheels, used so extensively in draining the fens of Lincolnshire, England, are made of cast-iron with wooden floats which form an angle of 45° with the horizon at the point where they deliver the water. The floats are otherwise like those of an undershot water-wheel, and move in a curved trough of masonry called the “breasting,” into which they fit exactly, the lower end of the trough being in the drain, and the upper discharging into the chute, which carries off the water on a higher level. It is just the converse of the water-wheel, being driven by steam and lifting the water. The diameter of the wheel is so proportioned to the lift, that the surface of the water at the outfall is below its axis. The speed of the surface of the wheel is 6 feet per second; a wheel of 35 to 40 feet for a 15-feet lift. One machine at Deeping Fen has a steam-engine of 80 horsepower, a water-wheel 28 feet in diameter, float-boards 5 1/2 feet in depth, 5 feet wide, moving 6 feet per second, discharging 165 cubic feet of water per second. The float-boards dip 3 feet 4 inches; the average consumption of coal was 10 1/2 pounds per horse-power per hour. A better duty is now attained, probably. This engine of 80 horse-power and another of 60 take the place, but much exceed the former efficiency of 44 windmills. Littleport Fen has 2 steam-engines of 110 horse-power, to drain 28,000 acres; superseding 75 windmills. The scoop-wheel is 35 feet in diameter, and weighs 54 tons. The pinion is 4 feet in diameter, weighs 3,696 pounds, and makes 13 revolutions per minute. When the tide is high this pinion works into a cogwheel 24 feet in diameter, having internal teeth; the floatboards on the scoop-wheel then move with a velocity of 212 feet per minute, and discharge in that time 3,519 cubic feet of water. When the tide is low, and so great an elevation of discharge is not required, the pinion is made to work in a cog-wheel 16 feet in diameter, and having external teeth; the float-boards then move at the rate of 318 feet per minute, and deliver 5,278 cubic feet in that time. In that wet district it is estimated that 7,260,000 cubic feet of water are annually raised and carried off from every 1,000 acres. A 10-horse-power steam-engine can remove this in 232 hours. The rainfall is estimated at 3 inches per month, of which two thirds is to be lifted and removed artificially, which is 7,260 cubic feet to the acre. In the district referred to, this quantity was formerly increased by the natural drainings of 12,000 acres of highlands, amounting to 40,000 cubic feet per minute in a rainy season. By catch-water drains this is now intercepted and carried off by a special channel and outlet. Glynn, C. E., England, makes the dip of his float-boards 5 feet, the axis 5 feet above the level of the outfall, the rate 6 feet per second at the circumference. Fig. 4681 shows a scoop-wheel employed at Lough Foyle. The [2056] engine fly-wheel a carries a pulley connected by a belt to the pulley b. whose shaft is provided with a pinion meshing with a spur-wheel on the shaft of the scoop-wheel c. d is the curved chase up which the water is driven into the chute e, passing through the embankment f, and conducted into the drain. |
| Scoop-wheel at Lough Foyle (section of wheel and bank). |
