Chain pump

Two types of hydraulic-powered chain pump from the Chinese encyclopedia Tiangong Kaiwu (1637), written by Song Yingxing

The chain pump is type of a water pump in which several circular discs are positioned on an endless chain. One part of the chain dips into the water, and the chain runs through a tube, slightly bigger than the diameter of the discs. As the chain is drawn up the tube, water becomes trapped between the discs and is lifted to and discharged at the top. Chain pumps were used for centuries in the ancient Middle East, Europe, and China.