A trip hammer, also known as a tilt hammer or helve hammer, is a massive powered hammer, usually raised by a cam and then released to fall under the force of gravity. Historically, trip hammers were often powered hydraulically by a water wheel. One or more trip hammers were set up in a forge, also known variously as a hammer mill, hammer forge or hammer works. Trip hammers are known to have been used in Imperial China since the Western Han dynasty. They also existed in the contemporary Greco-Roman world, with more evidence of their use in medieval Europe during the 12th century. During the Industrial Revolution the trip hammer fell out of favor and was replaced with the power hammer. Often multiple hammers were powered via a set of line shafts, pulleys and belts from a centrally located power supply. Traditional uses of trip hammers include pounding, decorticating and polishing of grain in agriculture. In mining, trip hammers were used for crushing metal ores into small pieces, although a stamp mill was more usual for this. In finery forges they were used for drawing out blooms made from wrought iron into more workable bar iron. They were also used for fabricating various articles of wrought iron, latten (an early form of brass), steel and other metals.
Early history
China
In ancient China, the trip hammer evolved out of the use of the mortar and pestle, which in turn gave rise to the treadle-operated tilt-hammer (Chinese: 碓 Pinyin: dui; Wade-Giles: tui). The latter was a simple device employing a lever and fulcrum (operated by pressure applied by the weight of one's foot to one end), which featured a series of catches or lugs on the main revolving shaft as well. This device enabled the labor of pounding, often in the decorticating and polishing of grain, and avoided manual pounding with hand and arm. Although Chinese historians assert that its origins may span as far back as the Zhou dynasty (1050 BC–221 BC), the British sinologist Joseph Needham regards the earliest texts to describe the device are the Jijiupian dictionary of 40 BC, Yang Xiong's Fangyan of 15 BC, as well as the "best statement" the Xin Lun written by Huan Tan about 20 AD (during the usurpation of Wang Mang). The latter book states that the legendary Fu Xi was the one responsible for the pestle and mortar (which evolved into the tilt-hammer and then trip hammer device). Although the author speaks of the mythological Fu Xi, a passage of his writing gives hint that the waterwheel and trip-hammer were in widespread use by the 1st century AD in China (for water-powered Chinese metallurgy, see Du Shi):
Fu Hsi invented the pestle and mortar, which is so useful, and later on it was cleverly improved in such a way that the whole weight of the body could be used for treading on the tilt-hammer (tui), thus increasing the efficiency ten times. Afterwards the power of animals—donkeys, mules, oxen, and horses—was applied by means of machinery, and water-power too used for pounding, so that the benefit was increased a hundredfold.
However, this passage as well as other early references from the Han era may rather refer to a water lever, not a trip hammer. Later research, pointing to two contemporary Han era funeral wares depicting hydraulic hammers, proved that vertical waterwheels were used to power batteries of trip hammers during the Han dynasty.
With his description, it is seen that the out-of-date Chinese term for pestle and mortar (dui, tui) would soon be replaced with the Chinese term for the water-powered trip-hammer (Chinese: 水碓; pinyin: shuǐ duì; Wade–Giles: shui tui. The Han dynasty scholar and poet Ma Rong (79–166 AD) mentioned in one of his poems of hammers 'pounding in the water-echoing caves'. As described in the Hou Han Shu, in 129 AD the official Yu Xu gave a report to Emperor Shun of Han that trip hammers were being exported from Han China to the Western Qiang people by way of canals through the Qilian Mountains. In his Rou Xing Lun, the government official Kong Rong (153–208 AD) remarked that the invention of the trip hammer was an excellent example of a product created by intelligent men during his own age (comparing the relative achievements of the sages of old). During the 3rd century AD, the high government official and engineer Du Yu established the use of combined trip hammer batteries (lian zhi dui), which employed several shafts that were arranged to work off one large waterwheel. In Chinese texts of the 4th century, there are written accounts of men possessing and operating hundreds of trip hammer machines, such as the venerable mathematician Wang Rong (died 306 AD), Deng Yu (died 326 AD), and Shi Chong (died 300 AD), responsible for the operation of hundreds of trip hammers in over thirty governmental districts throughout China. There are numerous references to trip hammers during the Tang dynasty (618–907 AD) and Song dynasty (960–1279), and there are Ming dynasty (1368–1644) references that report the use of trip hammers in papermills of Fujian Province. Although Chinese trip hammers in China were sometimes powered by the more efficient vertical-set waterwheel, the Chinese often employed the horizontal-set waterwheel in operating trip hammers, along with recumbent hammers. The recumbent hammer was found in Chinese illustrations by 1313 AD, with the publishing of Wang Zhen's Nong Shu book on ancient and contemporary (medieval) metallurgy in China. There were also illustrations of trip hammers in an encyclopedia of 1637, written by Song Yingxing (1587–1666). The Chinese use of the cam remained confined to the horizontal type and was limited to a "small variety of machines" that included only rice hulling and much later mica-pounders, paper mills and saw mills, while fulling stocks, ore stamps or forge hammers were unknown.
Classical antiquity
The main components for water-powered trip hammers – water wheels, cams, and hammers – were known in the Hellenistic world. Early cams are in evidence in water-powered automata from the 3rd century BC. According to M.J.T. Lewis, a flute player whose mechanism was described by the Persian Banū Mūsā brothers in the 9th century AD and can be "reasonably" attributed to Apollonius of Perge, functions on the principle of water-powered trip hammers. The Roman scholar Pliny (Natural History XVIII, 23.97) indicates that water-driven pestles had become fairly widespread in Italy by the first century AD:
… excerpt ends here. Continue reading the full article.
