MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

68Table 3.2 Manually-operated paddle-wheel performanceWheeldiameter(ft)NumberofpaddlesMan Powerrequired for1-hr. operationHeightliftedDischargeIft) (cfs) (cfh)4 88 12l-26-80.5-1.5 ,0.12 4431 .o-2.0 0.18 66410 16 8-12 1.5-2.5 0.31 110612 24 12-16 2.0-3.0 0.50 1770Although windmills originally drove these large scoop-wheels (Starling,1892), steam engines were later utilized as lifts up to 8 ft and dischargesof 250 cfs per wheel (at 2.0 ft heads) increasedthe power demand (Slichter,1910).3.3.1.2 Water LadderThe water ladder is another rotaryscooping device which isalso referred to in various forms as:rahad (Thai) link-belt box elevatordragon wheel (China)paddle pumpchain pumpIt consists of an inclined trough and a chain of paddles which is pulledthrough it by a-sprocket at the upper end--see Figure 3.18. The entiredevice can be made of wood, which allows for construction in developingareas and ease of maintenance. The driving sprocket is attached to ashaft which can be driven by several prime movers. Older designs usedthe same direct pedaling power as the paddle-wheel (3.3.1.1) or animalpowervia a circular-sweep and gearing (Schioler, 1975). Later designsincorporate windmills and small internal combustion engines. Using a small