Persian wheel

Device to lift water, particularly for agricultural purposes. It consists of an endless chain of buckets, typically with an individual capacity of 8-15 litres mounted on a drum and submerged in water to the required depth. The drum is connected to a toothed wheel held in a vertical plane by a long shaft usually kept below ground level. The vertical toothed wheel is geared with a large toothed horizontal wheel connected to a horizontal beam. This beam is yoked to a pair of animals. The animals move in a circle to turn the drum and raise the water. Water is released when the bucket reaches the top.
The average discharge rate from a Persian wheel is about 160-170 litres/min from a depth of 9m with one pair of bullocks. The Persian wheel can be used to raise water from a depth of up to 20 m but its efficiency is reduced at depths below 7.5 metres.