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A jackhammer ( pneumatic drill or demolition hammer in British English) is a pneumatic tool 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. US patent 550324 Steam or Pneumatic Engine Hand-held jackhammers are generally powered by compressed air, but some are also powered by . Larger jackhammers, such as rig-mounted hammers used on heavy equipment, are usually 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).
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 tunnel through Mount Fréjus to create a rail link between Italy and France, which would cross his realm.Drinker (1878), page 266.The project was called the "Mount Cenis tunnel" although the tunnel passed under Mount Fréjus. 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.Drinker (1878), page 152.
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.Drinker (1878), pages 168 and 266. (In 1855, a German, Schumann, invented a similar pneumatic rock drill in Freiburg, Germany.Drinker (1878), pages 151–152.) By 1861, Bartlett’s drill had been refined by the Savoy-born engineer Germain Sommeiller (1815-1871) and his colleagues, Grandis and Grattoni.Drinker (1878), pages 169 and 266. Thereafter, many inventors refined the pneumatic drill.See: Drinker (1878), page 168. See also: page 2 of Eustace M. Weston, Rock drills: design, construction and use (New York, New York: McGraw-Hill, 1910). Sommeiller took his drill to the lengthy Gotthard 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.
In United Kingdom, electromechanical versions are colloquially known by the name of "Kangos". The term comes from the former British brand name now owned by Milwaukee Tools. (1998). 9780333674642, Waterlow. ISBN 9780333674642
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.
Another method is overhead jackhammering, requiring strength conditioning and endurance to hold a smaller jackhammer, called a rivet buster, over one's head. To make overhead work safer, a platform can be used. One such platform is a positioner–actuator–manipulator (PAM). This unit takes all the weight and vibration from the user.
There are two methods to controlling dust caused by the use of a jackhammer, either through using a continuous spray of water at the point of impact, or using a hood or shroud with a vacuum dust collection system.
Modern versions use rotary screw compressors and have more sophisticated variable governors. The unit is usually mounted on a trailer and sometimes includes an electrical generator to supply lights or electric power tools.
Additionally, some users of pneumatic jackhammers may use a pneumatic lubricator which is placed in series with the air hose powering the air hammer. This increases the life and performance of the jackhammer.
Electric powered tools come in a variety of sizes, about . They require an external power source but do not require a compressor. Although in the past these tools did not have the power of an air or pneumatic hammer, this is changing with newer brushless-motor tools coming close to the power of a pneumatic tool and in some cases even matching it. Electric-powered tools are useful for locations where access to a compressor is limited or impractical, such as inside a building, in a crowded construction site, or in a remote location and it is not uncommon under earth moving equipment or tool.
Electropneumatic tools use a variety of chucks for attaching chisels, but the most common are SDS-max, 7/8 in hex, TE-S, and 1+1/8 in hex. The connection end size is also related to the breaking energy of the tool. For example, the Bosch and Hilti tools both use SDS-max, while the Bosch, Hilti, and Makita tools all use 1+1/8 in hex connection. See for more on electropneumatic hammering.
Advances in technology have allowed for portable hydraulic breakers. The jackhammer is connected with to a portable hydraulic powerpack: either a petrol or diesel engine driving a hydraulic pump; or a mini-excavator or skid-steer via a power take-off driveshaft to the machine's hydraulic system. Hydraulic power sources are more efficient than air compressors, making the kit smaller, cheaper or more powerful than a comparable pneumatic version.
Pneumatic or hydraulic tools are particularly likely to be used in underground Mining 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.
Sharpening: may be resharpened in a shop or with an angle grinder with grinding disc. After resharpening, they must then be heat treated to restore the integrity of the steel before use. Self-sharpening polygon and flat chisels are also available.
Use has been linked to Raynaud syndrome; in particular, prolonged exposure to the pronounced oscillation conducted by the tool can lead to a secondary form of the syndrome known as vibration white finger. Applying athletic tape is not very effective in preventing white finger but seems to help alleviate some of its discomfort. Pneumatic drill usage can also lead to a predisposition for the development of carpal tunnel syndrome.
Some manufacturers of electro-pneumatic tools now offer vibration reduction systems to reduce the vibration felt by the operator. For example, Hilti manufactures a jackhammer model that has approximately the same impact energy of a pneumatic hammer, but the vibration felt by the operator is significantly less (7 Acceleration). Other manufacturers such as Makita, DeWalt and Bosch also offer electric tools with vibration dampening.
In addition, using a jackhammer to break up concrete pavement may expose the operator to hazardous dust containing respirable crystalline Silicon dioxide that may induce silicosis. Publication date is date of last page update. The operator and those in the vicinity of the jackhammer operations should wear personal protective equipment, including an OSHA-approved respirator (US).
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