Jackhammer

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Drilling a blast hole with a jackhammer Tennessee Valley Authority Douglas Dam French Broad River Sevier County TN man with jackhammer 1942.gif
Drilling a blast hole with a jackhammer
(video) A construction worker uses a jackhammer in Japan.

A jackhammer (pneumatic drill or demolition hammer in British 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. [1] 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. humans are typically used to break up rock, pavement, and concrete.

Contents

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".

History

The first steam-powered drill was patented by Samuel Miller in 1806. The drill used steam only for raising the drill. [2] 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. [3] [4] 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. [5] The first American "percussion drill" was made in 1848, and patented in 1849 by Jonathan J. Couch of Philadelphia, Pennsylvania. [6] 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. [7] By 1850 or 1851, Fowle was using compressed air to drive his drill, making it the first true pneumatic drill. [8]

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. [9] [10] 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. [11]

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. [12] (In 1855, a German, Schumann, invented a similar pneumatic rock drill in Freiburg, Germany. [13] ) By 1861, Bartlett’s drill had been refined by the Savoy-born engineer Germain Sommeiller (1815-1871) and his colleagues, Grandis and Grattoni. [14] Thereafter, many inventors refined the pneumatic drill. [15] 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. [16]

In Britain, electromechanical versions are colloquially known as "Kangos". [17] [ self-published source? ] The term comes from the former British brand name now owned by Milwaukee tools.

Use

A Wacker Neuson gasoline-powered breaker on a demolition site BH E02 web.jpg
A Wacker Neuson gasoline-powered breaker on a demolition site

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.

Types

Pneumatic

A compressor for running a pneumatic jackhammer Aa pneumatic drill compressor front.jpg
A compressor for running a pneumatic jackhammer

A pneumatic jackhammer, also known as a pneumatic drill or pneumatic hammer, [18] 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 compressors 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:

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

A single-phase demolition breaker Makita demolition breaker.jpg
A single-phase demolition breaker

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. [19]

Electric powered tools come in a variety of sizes, about 12–65 lb (5.4–29.5 kg). 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 12 lb (5.4 kg) tools both use SDS-max, while the Bosch, Hilti, and Makita 65 lb (29 kg) tools all use 1+1/8 in hex connection. See hammer drills for more on electropneumatic hammering.

Hydraulic

An excavator-mounted hydraulic jackhammer being used to break up concrete. Excavator jackhammer.jpg
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 excavators or backhoes and is widely used for roadwork, quarrying and general demolition or construction groundwork. [20] 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.

Hydraulic breakers 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 hoses 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.

Bits (chisels)

Bit types include

Sharpening

Chisels 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.

Health effects

A jackhammer with black silencer attached Pneumatic drill.jpeg
A jackhammer with black silencer attached

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. [21] 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 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 60 lb (27 kg) pneumatic hammer, but the vibration felt by the operator is significantly less (7  m/s2). Other manufacturers such as Makita, DeWalt and Bosch 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. [22] The operator and those in the vicinity of the jackhammer operations should wear personal protective equipment respirators, more precisely, an OSHA-approved respirator.

Related Research Articles

Engine machine that converts one form of energy into mechanical energy

An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines convert heat into work via various thermodynamic processes. The internal combustion engine is perhaps the most common example of a heat engine, in which heat from the combustion of a fuel causes rapid pressurisation of the gaseous combustion products in the combustion chamber, causing them to expand and drive a piston, which turns a crankshaft. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and ultimately motion.

Pneumatics Branch of engineering

Pneumatics is a branch of engineering that makes use of gas or pressurized air.

Drill Tool used to create holes

A drill or drilling machine is a tool primarily used for making round holes or driving fasteners. It is fitted with a bit, either a drill or driver, depending on application, secured by a chuck. Some powered drills also include a hammer function.

Air compressor Machine to pressurise air

An air compressor is a pneumatic device that converts power into potential energy stored in pressurized air. By one of several methods, an air compressor forces more and more air into a storage tank, increasing the pressure. When the tank's pressure reaches its engineered upper limit, the air compressor shuts off. The compressed air, then, is held in the tank until called into use. The energy contained in the compressed air can be used for a variety of applications, utilizing the kinetic energy of the air as it is released and the tank depressurizes. When tank pressure reaches its lower limit, the air compressor turns on again and re-pressurizes the tank. An air Compressor must be differentiated from a pump because it works for any gas/air, while pumps work on a liquid.

Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches and others, as well as to atomize paint, to operate air cylinders for automation, and can also be used to propel vehicles. Brakes applied by compressed air made large railway trains safer and more efficient to operate. Compressed air brakes are also found on large highway vehicles.

Compressor Machine to increase pressure of gas by reducing its volume

A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.

For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. In hydraulics, water or hydraulic fluid transfers force between hydraulic components such as hydraulic pumps, hydraulic cylinders, and hydraulic motors that are assembled into hydraulic machinery, hydraulic drive systems, etc. In pneumatics, the working fluid is air or another gas which transfers force between pneumatic components such as compressors, vacuum pumps, pneumatic cylinders, and pneumatic motors. In pneumatic systems, the working gas also stores energy because it is compressible.

Drilling rig Integrated system to drill wells

A drilling rig is an integrated system that drills wells, such as oil or water wells, in the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person and such are called augers. Drilling rigs can sample subsurface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures. The term "rig" therefore generally refers to the complex equipment that is used to penetrate the surface of the Earth's crust.

Quasiturbine

The Quasiturbine or Qurbine engine is a proposed pistonless rotary engine using a rhomboidal rotor whose sides are hinged at the vertices. The volume enclosed between the sides of the rotor and the rotor casing provide compression and expansion in a fashion similar to the more familiar Wankel engine, but the hinging at the edges allows the volume ratio to increase. A geometrical indetermination of the Quasiturbine confinement stator shape allows for a variety of profiles and design characteristics. Unlike vane pumps, in which vane extension is generally important and against which the pressure acts to generate the rotation, the Quasiturbine contour seals have a minimal extension and the rotation does not result from pressure against these seals.

Pneumatic motor

A pneumatic motor, or compressed air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air energy to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor, piston air motor, air turbine or gear type motor.

Pneumatic tool

A pneumatic tool, air tool, air-powered tool or pneumatic-powered tool is a type of power tool, driven by compressed air supplied by an air compressor. Pneumatic tools can also be driven by compressed carbon dioxide (CO2) stored in small cylinders allowing for portability.

Pile driver

A pile driver is a device used to drive piles into soil to provide foundation support for buildings or other structures. The term is also used in reference to members of the construction crew that work with pile-driving rigs. One type of pile driver uses a weight placed between guides so that it can slide vertically. It is placed above a pile. The weight is raised, which may involve the use of hydraulics, steam, diesel, or manual labour. When the weight reaches its highest point it is released, and hits the pile, driving it into the ground.

Rotary-screw compressor Gas compressor using a rotary positive-displacement mechanism

A rotary-screw compressor is a type of gas compressor, such as an air compressor, that uses a rotary-type positive-displacement mechanism. These compressors are common in industrial applications and replace more traditional piston compressors where larger volumes of compressed gas are needed, e.g. for large refrigeration cycles such as chillers, or for compressed air systems to operate air-driven tools such as jackhammers and impact wrenches. For smaller rotor sizes the inherent leakage in the rotors becomes much more significant, leading to this type of mechanism being less suitable for smaller compressors than piston compressors.

A drifter drill or drifter is a hydraulic or pneumatic rock or ground drill used to make horizontal holes in tunnel construction and mining. It is mounted on a feed, which is like a rail that the drill travels on or drifts. This kind of drilling procedure is also called drifting. The feed is usually attached with a flexible boom to a stationary or mobile unit that contains the powerpack. Drifters are used in mining, construction, exploration, and natural science.

Free-piston engine

A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.

Holman Brothers

Holman Brothers Ltd. was a mining equipment manufacturer founded in 1801 based in Camborne, Cornwall, England.

Rotary hammer

A rotary hammer is a power tool that can perform heavy-duty tasks such as drilling and chiseling hard materials. It is similar to a hammer drill in that it also pounds the drill bit in and out while it is spinning. However, rotary hammers use a piston mechanism instead of a special clutch. This causes them to deliver a much more powerful hammer blow, making it possible to drill bigger holes much faster.

Fluid deforms continuously on the application of shear stress, no matter how much small is it. Fluid comprises both gases and liquid. The technique of using liquid for power transmission is called as hydraulics while which uses gases for power transmission is called Pneumatics. In most hydraulic systems, mineral oils will be used while in most pneumatic systems, atmospheric air will be used.

Chicago Pneumatic, also known as "CP", is an industrial manufacturer providing power tools, air compressors, generators, light towers and hydraulic equipment. Products are sold in more than 150 countries through a worldwide distribution network. CP is active on markets such as tools for industrial production, vehicle service, maintenance repair operation for mining, construction, infrastructure equipment.

A bash valve is a valve within a piston engine, used to control the admission of the working fluid. They are directly actuated valves, operated by contact between the piston and the valve tip.

References

Air hose connection on pneumatic drill Aa pneumaticdrill hosecoupling 01.jpg
Air hose connection on pneumatic drill
  1. US patent 550324 Steam or Pneumatic Engine
  2. "Minutes of Proceedings of the Institution of Civil Engineers". 1891.
  3. Brunton, C. (September 21, 1844) "Design of wind hammer for boring rocks," The Mechanics' Magazine, 41 : 203–204.
  4. West, Graham, Innovation and the Rise of the Tunnelling Industry (Cambridge, England: Cambridge University Press, 1988), p. 33.
  5. Office, Patent (1874). "Patents for inventions. Abridgments of specifications".
  6. Henry S. Drinker,Tunneling, explosive compounds, and rock drills … (New York, New York: John Wiley & Sons, 1878), pages 153-157.
  7. Drinker (1878), page 160.
  8. Drinker (1878), page 164.
  9. Drinker (1878), page 266.
  10. The project was called the "Mount Cenis tunnel" although the tunnel passed under Mount Fréjus.
  11. Drinker (1878), page 152.
  12. Drinker (1878), pages 168 and 266.
  13. Drinker (1878), pages 151-152.
  14. Drinker (1878), pages 169 and 266.
  15. 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).
  16. How It Works - Horobin, Wendy; Marshall Cavendish Corporation, Third Edition, Page 1195
  17. Ellis, Iain (7 September 2006). Ellis' British Railway Engineering Encyclopaedia. lulu.com. p. 371. ISBN   9781847286437 . Retrieved 17 February 2014.[ self-published source ]
  18. Hughes, Phil; Ferrett, Ed (2008-06-12). Introduction to Health and Safety in Construction. ISBN   9781856175210.
  19. Clint DeBoer. "How's It Work? Rotary Hammers". Pro Tool Reviews. Retrieved June 22, 2016.
  20. "What are Hydraulic Hammers? (with pictures)". wiseGEEK. Retrieved 2020-03-12.
  21. Murphy, William J. (June 3, 2019). "The Effect of Hearing Protection on Kurtosis" (PDF). Inter Noise 2019, Madrid.
  22. "Workplace Safety & Health Topics: Silica: Jackhammer". Centers for Disease Control and Prevention. 29 July 2013. Retrieved 20 December 2014. Publication date is date of last page update.