A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. Depictions of Greek and Roman water screws show the screws being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw. A screw could be sealed with pitch or some other adhesive to its casing, or, cast as a single piece in bronze, as some researchers have postulated as being the devices used to irrigate Nebuchadnezzar II's Hanging Gardens of Babylon. The "screw" does not necessarily need to turn inside the casing, but can be allowed to turn with it in one piece. Also, water leaking from the top section of the screw leaks into the previous one and so on, so a sort of equilibrium is achieved while using the machine, thus preventing a decrease in efficiency.
The contact surface between are the screw and the pipe does not need to be perfectly water-tight because of the relatively large amount of water being scooped at each turn in respect to the angular speed of the screw. This amount of water will slide up in the spiral tube as the shaft is turned, until it finally pours out from the top of the tube and feeds the irrigation systems.
#Archimedes screw pump design manual manual#
The screw is turned (usually by a windmill or by manual labour).Īs the bottom end of the tube turns, it scoops up a volume of water. A screw can be thought of as an inclined plane (another simple machine) wrapped around a cylinder. The machine consists of a screw inside a hollow pipe.
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