Waterwheels work by using the force of water flowing or falling onto pedals inside the wheel to turn it. This rotation then allows the shaft of the wheel to transmit the energy created to move machinery.
The are three major types of waterwheels: one horizontal and two vertical types. The horizontal waterwheel allows water to flow from an aqueduct into the wheel, creating forward action that causes the wheel to rotate. An overshot vertical waterwheel allows water from an aqueduct to fall on top of the wheel and uses gravity to rotate it. The third type is the undershot vertical waterwheel and is placed in a stream to be rotated by the motion of the river.
Waterwheels may have been the first method used by people to create mechanical energy that did not involve the use of animals or people. A Greek writer, Antipater, wrote the first known reference to a waterwheel in around 4000 B.C. He tells of the reduced of workload of young women who previously had to operate handheld mills to grind corn.
Early uses for waterwheels included crop irrigation, supplying drinking water and grinding grains. People later invented ways to run sawmills, forge bellows, textile mills and other machines using waterwheels.