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af
764
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530 Molesworth’s pocket-book
roNCELBi's Undershot Wateb-whbbl.
h — Head of water |n feet. .
Q = Quantity of water in cube feet per minute.
HP — Effective horse-power.
Velocity of periphery = V X 0-55.
For values of see Table of theoretical velocity of water.
Number of bucket« = 1 ■ 6 D + 16 when D = diameter of wneel in feet.
The sluice-openini? should be covered by at least two buckets.
Depth of shrouding from Ard to j of the fall of water. Diameter of
■wheel = 2h; but the diameter of the wheel should not be less thi»n
7 feet or more than 16.
Construction of floats:— , _ .
Let A B represent the direction of the supply, and lay off a tangent to
the periphery of the wheel at the centre of the sluice. Kaise AC perpen-
dicular to A B. and make C D =‘4BC. Joui AD and diaw B E parallel
to A D; then B E is the tangent to the curve of the float at its poujt. The
curve may be struck with a radius of 1'2 depth of shrouding.
The curb should fit the wheel accurately for 18 or 20 inches, measured
back from the perpendicular line which passes through the axis of the
wheel; the breast should then incline 1 in 10, or 1 in 15 towards the sluice.
After passing the axis of the wheel ju th© tail-race the curb should
make a sudden dip of 6 inches.