A jackhammer (pneumatic drill or demolition hammer in British English
) is a pneumatic
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 motor
s. Larger jackhammers, such as rig-mounted hammers used on construction machinery
, are usually hydraulic
ally powered. Jackhammers are typically used to break up rock
, and concrete
A jackhammer operates by driving an ''internal'' hammer up and down. The hammer is first driven down to strike the back 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).
In British English, electromechanical versions are colloquially known as "Kangos".
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 a 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 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
), 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 Europe and America respectively, each holding significant patents.
The word "jackhammer" is used in North American English
, while "pneumatic drill" is used colloquially
elsewhere in the English speaking world
, although strictly speaking a "pneumatic drill" refers to a pneumatic
ally driven jackhammer.
versions are colloquially known as "Kangos".
The term comes from the former British brand name now owned by Milwaukee tools
A full-sized portable jackhammer is impractical for use against walls and steep slopes, except by a very strong person, as the user would have to both support the weight of the tool, and push the tool back against the work after each blow. A technique developed by experienced workers is a two-man team to overcome this obstacle of gravity: one operates the hammer and the second assists by holding the hammer either on his shoulders or cradled in his arms. Both use their combined weight to push the bit into the workface. This method is commonly referred to as horizontal jackhammering.
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.
A pneumatic jackhammer, also known as a ' or ', is a jackhammer that uses compressed air as the power source. The air supply usually comes from a portable air compressor
driven by a diesel engine
. Reciprocating compressor
s were formerly used. The unit comprised a reciprocating compressor driven, through a centrifugal clutch
, by a diesel engine. The engine's governor
provided only two speeds:
* idling, when the clutch was disengaged
* maximum, when the clutch was engaged and the compressor was running
Modern versions use rotary 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.
Electro mechanical or electropneumatic
An electropneumatic hammer is often called a rotary hammer, because it has an electric motor, which rotates a crank. The hammer has two pistons – a drive piston and a free flight piston. The crank moves the drive piston back and forth in the same cylinder as the flight piston. The drive piston never touches the flight piston. Instead the drive piston compresses air in the cylinder, which then propels the flight piston against a striker, which contacts the drill bit.
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
tools both use SDS-max, while the Bosch, Hilti, and Makita
tools all use 1+1/8 in hex connection. See hammer drill
s for more on electropneumatic hammering.
thumb|An excavator-mounted hydraulic jackhammer being used to break up concrete.
A hydraulic jackhammer, generally much larger than portable ones, may be fitted to mechanical excavator
s or backhoe
s and is widely used for roadwork, quarrying and general demolition or construction groundwork. These larger machine mounted breakers are known as Rig Mounted, or Machine Mounted Breakers. Such tools can also be used against vertical walls (or ceilings for that matter), since the vehicles involved are massive enough and powerful enough to exert the forces involved without needing the help of gravity in operating the tool. Pneumatic or hydraulic tools are particularly likely to be used in mines
where there is an explosion risk (such as underground coal
mines), since they lack any high-power electrical circuitry that might cause a triggering spark.
usually use a hydraulic motor driving a sealed pneumatic hammer system, as a hydraulic hammer would develop a low strike speed and transfer unacceptable shock loads to the pump system.
Advances in technology have allowed for portable hydraulic breakers
. The jackhammer is connected with hydraulic hose
s to a portable hydraulic powerpack: either a petrol or diesel engine driving a hydraulic pump; or a mini-excavator
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.
Bit types include
* Spade – provides flat finish for concrete or edging in asphalt or dirt.
* Flat tip – allows direction control or finer edge finish
* Point – general breaking
* Stake driver – drives concrete form stakes
* Scabbler – finishes surface smooth or for cleaning prior to bonding
* Flex chisel – flexible metal blade (attached to shank with bolts) for tile removal and scraping
* Bushing tool – multiple carbide points for cleaning up seams and knocking down rough spots in concrete
s 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.
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. 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, the primary noise source comes from the chisel striking the object being removed.
Use has been linked to Raynaud syndrome
; in particular, prolonged exposure to the pronounced vibration
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 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 m/s2
). Other manufacturers such as Makita
also offer electric tools with vibration dampening.
Using a jackhammer to break up concrete pavement may expose the operator to hazardous dust
containing respirable crystalline silica
[ Publication date is date of last page update.]
The operator and those in the vicinity of the jackhammer operations should wear personal protective equipment respirators, more precisely, an OSHA approved respirator.
How jackhammers workHow Rotary Hammers Work
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