Chain pump

Chain pump

The chain pump is a type of water pump where an endless chain has positioned on it a series of circular discs. One end of the chain dips in to 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. Historically, chain pumps were known and used for centuries in the ancient Middle East, Europe, and China.

Chain pumps in the Middle East and Rome

The earliest evidence for this device occurred in a Babylonian text from circa 700 BC and may be referred to in Ecclesiastes 12:6. These were commonly powered by human or animal power. The device then appeared in ancient Egypt from circa 200 BC, featuring a pair of gear-wheels.

A version of this kind of pump was known in ancient Roman times, sometimes with pots fixed to the chain, which, as they passed over the top pulley, tipped the water out. This was written of by Philo of Byzantium in the 2nd century BC, mentioned by the historian Vitruvius around 30 BC, and fragments of these buckets were found on the Roman barges of Lake Nemi.

Complex chain pumps consisting of over 200 separate components were used extensively by Muslim inventors and engineers in the medieval Islamic world, where they are known as saqiya. The mechanical flywheel, used to smooth out the delivery of power from a driving device to a driven machine, was first employed by Ibn Bassal (fl. 1038-1075) of Islamic Spain for use in a saqiya chain pump.

An intricate device was featured in a manuscript by Al-Jazari in 1206, with chambered reservoirs, water wheel scoops, gear-wheels, and a chain pump, powered by the pull of an ox and water falling by gravity. The first known use of a crankshaft in a chain pump was featured in another one of al-Jazari's saqiya machines. The concept of minimizing intermittent working is also first implied in one of al-Jazari's saqiya chain pumps, which was for the purpose of maximising the efficiency of the saqiya chain pump. Al-Jazari also constructed a water-raising saqiya chain pump which was run by hydropower rather than manual labour, though the Chinese were also using hydropower for chain pumps prior to him. Saqiya machines like the ones he described have been supplying water in Damascus since the 13th century up until modern times, and were in everyday use throughout the medieval Islamic world.

Chain pumps were used in European mines during the Renaissance era, and illustrated by the mineralogist Georg Agricola in his De re metallica of 1556. They were used in dockyards, and a number formed part of the Portsmouth Block Mills complex. Chain pumps were commonly used on naval vessels of the time to pump the bilges, and examples are known in the nineteenth century for low-lift irrigation purposes.

Square-pallet in China

Chain pumps were also used in ancient China by at least the 1st century AD. One of the earliest accounts was a description by the Han Dynasty philosopher Wang Chong (2797 AD) around 80 AD. Unlike those found in the West, chain pumps in China resembled the square-pallet type instead of the pear-shaped bucket. Illustrations of such Chinese chain pumps show them drawing water up a slanting channel. These were sometimes powered by hydraulics of a rushing current against a horizontal water wheel acting against a vertical wheel, and others by a horizontal mechanical wheel acting upon a vertical wheel which was pulled by the labor of oxen. There was also square-pallet chain pumps operated manually by foot pedals. From the 1st century onwards, chain pumps were in widespread use and by many accounts could be spotted numerously throughout the Chinese countryside. Chinese square-pallet chain pumps were used largely for irrigation, yet they found use in public works as well. The infamous Eastern Han court eunuch Zhang Rang (d. 189 AD) once ordered the engineer Bi Lan to construct a series of square-pallet chain pumps outside the capital city of Luoyang. These chain pumps serviced the palaces and living quarters of the capital city as the water lifted by the chain pumps were brought in by a pipe system. Ma Jun, the renowned mechanical engineer of the Three Kingdoms era, also constructed a series of chain pumps for watering the palatial gardens of Emperor Ming of Wei (226-239).

From the 13th century onwards, the Chinese also used windmills (adopted from the Islamic world) as a means to power the motion of square-pallet chain pumps. Yet there were other types of chain pumps besides the square-pallet design. In Song Yingxing's (1587-1666) encyclopedic book the Tiangong Kaiwu of 1637, there is description and illustration of a cylinder-type chain pump, powered by waterwheels and leading water up from the river to an elevated plane full of agricultural crops.

See also

Notes

References

  • Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering. Taipei: Caves Books, Ltd.
  • Needham, Joseph (1986). Science and Civilization in China: Volume 6, Biology and Biological Technology, Part 2, Agriculture. Taipei: Caves Books Ltd.
  • Song, Yingxing, translated with preface by E-Tu Zen Sun and Shiou-Chuan Sun (1966). T'ien-Kung K'ai-Wu: Chinese Technology in the Seventeenth Century. University Park: Pennsylvania State University Press.

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