Screw turbine connected to a generator through a gearbox. The Archimedean screw is an ancient invention, attributed to Archimedes of Syracuse (287–212 BC.), and commonly used to raise water from a watercourse for irrigation purposes. In 1819 the French engineer Claude Louis Marie Henri Navier (1785–1836) suggested using the Archimedean screw as a type of water wheel. In 1916 William Moerscher applied for a U.S. patent on the hydrodynamic screw turbine. The Archimedean screw turbine is applied on rivers with a relatively low head (from 1 m to 10 m) and on low flows (0.01 m³/s up to around 10 m³/s on
Screw wire or rod is then cut to the proper length for the type of screw being made; this workpiece is known as a "blank". It is then cold headed, which is a cold working process. Heading produces the "head" of the screw. The shape of the die in the machine dictates what features are pressed into the screw head; for example a flat head screw uses a flat die. For more complicated shapes two heading processes are required to get all of the features into the screw head. This production method is used because heading has a very high production