TLDR: The Archimedes' screw is an ancient water pumping mechanism that uses a screw-shaped surface inside a pipe to transfer water from a low-lying area to higher ground. It was invented by the Greek mathematician Archimedes around 234 BC, but evidence suggests that it was used in Ancient Egypt even before that. The screw pump is one of the oldest hydraulic machines and has been used for centuries to irrigate fields, drain mines, and transport water. Today, Archimedes screw pumps are commonly used in wastewater treatment plants and for dewatering low-lying regions.
The Archimedes' screw consists of a screw-shaped surface surrounding a central cylindrical shaft inside a hollow pipe. When the screw is turned, it scoops up water from the bottom and pushes it up the tube until it pours out from the top. It's important to note that the screw must not be completely filled with water; there needs to be air pockets between the scoops of water. This allows the pump to function properly. The contact surface between the screw and the pipe doesn't need to be watertight, as long as the amount of water being scooped is larger than the amount leaking out. The screw can be turned by various means, such as windmills, manual labor, or motors.
Archimedes screws have a wide range of uses. They are commonly used in sewage treatment plants because they can handle varying rates of flow and suspended solids. They are also used in snow blowers, grain elevators, and concrete mixer trucks. In fish hatcheries, escalator-like Archimedes screws are used to safely transport fish from one location to another. The screw has even been used to stabilize the Leaning Tower of Pisa and in chocolate fountains.
There are also variations of the Archimedes screw, such as the screw conveyor, which is used to transport materials like plastic granules and cereal grains. It can also be found in injection molding machines, die casting machines, and extrusion of plastics. The screw can be used to compress and melt materials in these applications. Additionally, there are reverse action Archimedes screws, known as screw turbines, which can be used to generate electricity when water is fed into the top of the screw.
In summary, the Archimedes' screw is an ancient water pumping mechanism that uses a screw-shaped surface inside a pipe to transfer water from a low-lying area to higher ground. It has been used for centuries for various purposes, including irrigation, drainage, and transportation. Today, it is still widely used in wastewater treatment plants and has even found applications in fish hatcheries, snow blowers, and chocolate fountains.