Jackhammer
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).
[4][5] 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.
In 1849, Couch's assistant, Joseph W. Fowle, filed a patent caveat for a percussion drill of his own design.
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.
[12] 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.
[14]) By 1861, Bartlett’s drill had been refined by the Savoy-born engineer Germain Sommeiller (1815-1871) and his colleagues, Grandis and Grattoni.
[16] Sommeiller took his drill to the lengthy Gotthard Pass Tunnel, then being built to link railways between Switzerland and Italy under the Alps.
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.
[19] Additionally, the terms drill and breaker (demolition hammer) are non-interchangeable and refer to two differing 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.
See hammer drills for more on electropneumatic hammering.A hydraulic breaker may be fitted to heavy equipment such as an excavator or backhoe, and is widely used for roadwork, quarrying, construction sitework, and general demolition.
Pneumatic or hydraulic tools are particularly likely to be used in underground mines where there is an explosion risk (such as with coal), since they do not require high-voltage electricity to work, eliminating much of the danger of spark-induced detonation.
Bit types include: Sharpening: chisels may be resharpened in a shop or with an angle grinder with grinding disc.
The sound of the hammer blows, combined with the explosive air exhaust, makes pneumatic jackhammers dangerously loud, emitting more than 120 dB SPL near the operator’s ears.
[23] Sound-blocking earmuffs and earplugs must be worn by the operator to prevent a form of hearing loss, of which tinnitus is the main symptom.
Although some pneumatic jackhammers now have a silencer around the barrel of the tool, loud air exhaust, hammer blows themselves, and compressor engine sounds remain unmuffled.
For example, Hilti manufactures a jackhammer model that has approximately the same impact energy of a 60 lb (27 kg) pneumatic hammer, but the vibration felt by the operator is significantly less (7 m/s2).
In addition, using a jackhammer to break up concrete pavement may expose the operator to hazardous dust containing respirable crystalline silica that may induce silicosis.
