A jackhammer (pneumatic drill, breaker, demolition hammer or road hammer in Commonwealth English) is a pneumatic or electro-mechanical tool that combines a hammer directly with a chisel. It was invented by William McReavy, who then sold the patent to Charles Brady King. Hand-held jackhammers are generally powered by compressed air, but some are also powered by electric motors. Larger jackhammers, such as rig-mounted hammers used on construction machinery, are usually hydraulically powered. These tools are typically used to break up rock, pavement, and concrete. A jackhammer operates by driving an internal hammer up and down. The hammer is first driven down to strike the chisel and then back up to return the hammer to the original position to repeat the cycle. The effectiveness of the jackhammer is dependent on how much force is applied to the tool. It is generally used like a hammer to break the hard surface or rock in construction works and it is not considered under earth-moving equipment, along with its accessories (i.e., pusher leg, lubricator).
History The first steam-powered drill was patented by Samuel Miller in 1806. The drill used steam only for raising the drill. Pneumatic drills were developed in response to the needs of mining, quarrying, excavating, and tunneling. A pneumatic drill was proposed by C. Brunton in 1844. In 1846, a percussion drill that could be worked by steam, or atmospheric pressure obtained from a vacuum, was patented in Britain by Thomas Clarke, Mark Freeman, and John Varley. The first American "percussion drill" was made in 1848, and patented in 1849 by Jonathan J. Couch of Philadelphia, Pennsylvania. In that drill, the drill bit passed through the piston of a steam engine. The piston snagged the drill bit and hurled it against the rock face. It was an experimental model. In 1849, Couch's assistant, Joseph W. Fowle, filed a patent caveat for a percussion drill of his own design. In Fowle's drill, the drill bit was connected directly to the piston in the steam cylinder; specifically, the drill bit was connected to the piston's crosshead. The drill also had a mechanism for turning the drill bit around its axis between strokes and for advancing the drill as the hole deepened. By 1850 or 1851, Fowle was using compressed air to drive his drill, making it the first true pneumatic drill. The demand for pneumatic drills was driven especially by miners and tunnelers because steam engines needed fires to operate and the ventilation in mines and tunnels was inadequate to vent the fires' fumes. As well, mines and tunnels might contain flammable explosive gases such as methane. There was also no way to convey steam over long distances, such as from the surface to the bottom of a mine, without it condensing. By contrast, compressed air could be conveyed over long distances without loss of its energy, and after the compressed air had been used to power equipment, it could ventilate a mine or tunnel. In Europe since the late 1840s, the king of Sardinia, Carlo Alberto, had been contemplating the excavation of a 12-kilometer (7.5 mi) tunnel through Mount Fréjus to create a rail link between Italy and France, which would cross his realm. The need for a mechanical rock drill was obvious and that sparked research in Europe on pneumatic rock drills. A Frenchman, François Cavé (fr), designed a rock drill that used compressed air, which he patented in 1851. However, the air had to be admitted manually to the cylinder during each stroke, so it was not successful. In 1854, in England, Thomas Bartlett made and then patented (1855) a rock drill, the bit of which was connected directly to the piston of a steam engine. In 1855, Bartlett demonstrated his drill, powered by compressed air, to officials of the Mount Fréjus tunnel project. (In 1855, a German, Schumann, invented a similar pneumatic rock drill in Freiburg, Germany.) By 1861, Bartlett’s drill had been refined by the Savoy-born engineer Germain Sommeiller (1815-1871) and his colleagues, Grandis and Grattoni. Thereafter, many inventors refined the pneumatic drill. Sommeiller took his drill to the lengthy Gotthard Pass Tunnel, then being built to link railways between Switzerland and Italy under the Alps. From there, mining and railway tunnelling expanded. Two equipment manufacturing companies, Atlas Copco and Ingersoll Rand, became dominant in the provision of compressed air drilling apparatus in Europe and America respectively, each holding significant patents.
Terminology The word "jackhammer" is used in North American English and Australia, while "pneumatic drill" is used colloquially elsewhere in the English-speaking world, although strictly speaking a "pneumatic drill" refers to a pneumatically driven jackhammer. In Britain, electromechanical versions are colloquially known by the name of "Kangos". The term comes from the former British brand name now owned by Milwaukee Tools. Additionally, the terms drill and breaker (demolition hammer) are non-interchangeable and refer to two distinct types of jackhammer (regardless of their power source). A breaker cannot rotate its steel (which for example may be either a chisel or spike) and relies on pure percussion shock to fracture and split material without cutting, whereas a (pneumatic/hydraulic) drill both impacts and rotates, which enables a steel with a tungsten carbide tipped bit to cut into hard rock such as granite, typically to create holes for blasting. Normally, only the pneumatic drill would be used at geological operations such as quarrying or mining and only the breaker at civil operations such as construction and road repair.
Use
… excerpt ends here. Continue reading the full article.
