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Jackhammer

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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 King1 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 They 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 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 ie, pusher leg, lubricator

In British English, electromechanical versions are colloquially known as "Kangos"

Contents

  • 1 History
  • 2 Terminology
  • 3 Use
  • 4 Types
    • 41 Pneumatic
    • 42 Electro mechanical or electropneumatic
    • 43 Hydraulic
  • 5 Bits chisels
  • 6 Health effects
  • 7 References
  • 8 External links

Historyedit

Pneumatic drills were developed in response to the needs of mining, quarrying, excavating, and tunneling In 1806 Samuel Miller invented a steam driven percussion drill23 In 1838 Isaac Singer invented another steam driven drill A pneumatic drill was proposed by a C Brunton in 18444 The first "percussion drill" was made in 1848 and patented in 1849 by Jonathan J Couch of Philadelphia, Pennsylvania5 In this 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 deepened6 By 1850 or 1851, Fowle was using compressed air to drive his drill, making it the first true pneumatic drill7

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; there was also no way to convey steam over long distances eg, from the surface to the bottom of a mine; and mines and tunnels occasionally contained flammable explosive gases such as methane 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 75 mi tunnel through Mount Fréjus to create a rail link between Italy and France, which would cross his realm89 The need for a mechanical rock drill was obvious and this sparked research on pneumatic rock drills in Europe A Frenchman, Cavé, designed, and in 1851 patented, a rock drill that used compressed air; but the air had to be admitted manually to the cylinder during each stroke, so it was not successful10 In 1854, in England, Thomas Bartlett made and then patented 1855 a rock drill whose drill bit was connected directly to the piston of a steam engine In 1855 Bartlett demonstrated his drill, powered by compressed air, to officials of the Mt Fréjus tunnel project11 In 1855, a German, Schumann, invented a similar pneumatic rock drill in Freiburg, Germany12 Bartlett’s drill was refined by the Savoy-born engineer Germain Sommeiller 1815-1871 and his colleagues, Grandis and Grattoni, by 186113 Thereafter, many inventors refined the pneumatic drill14

Terminologyedit

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 jackhammer15

In Britain, electromechanical versions are colloquially known as "Kangos"16 The term comes from the former British brand name now owned by Milwaukee tools

Useedit

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-person team to overcome this obstacle of gravity: one person operates the hammer and the second assists by holding the hammer either on their shoulders or cradled in their 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 PAM Positioner Actuator Manipulator This unit takes all the weight and vibration from the user

Typesedit

Pneumaticedit

A compressor for running a pneumatic jackhammer

A pneumatic jackhammer, also known as a pneumatic drill or pneumatic hammer,17 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:

  • 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 Specific lubricant is filled in the pneumatic lubricator Furthermore, air compressors typically incorporate moisture into the compressed air leading to freeze-ups of the jackhammer or air hammer in cold weather

Electro mechanical or electropneumaticedit

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 bit18

Electric powered tools come in a variety of sizes from about 12 lbs - 65 lbs 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 come 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" Hex, TE-S, and 1-1/8" Hex The connection end size is also related to the breaking energy of the tool For example, the Bosch and Hilti 12 lb tools both use SDS-max, while the Bosch, Hilti, and Makita 65 lbs tools all use 1-1/8" Hex connection See Wikipedia article on hammer drills for more on electropneumatic hammering

Hydraulicedit

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 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 chiselsedit

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

Chisel sharpening:

Chisels may be sharpened in a shop or with an angle grinder with grinding disc After sharpening, they must then be heat treated to restore the integrity of the steel before use As an alternative, Hilti also manufacturers self sharpening polygon and flat chisels in SDS-max, TE-S, and 1-1/8" Hex connection ends

Health effectsedit

A jackhammer with black silencer attached

The sound of the hammer blows, combined with the explosive air exhaust, makes pneumatic jackhammers dangerously loud, emitting 100 decibels at two meters Sound-blocking earmuffs must be worn by the operator to prevent a form of hearing damage of which tinnitus is the main symptom Most pneumatic jackhammers now have a silencer around the barrel of the tool

Use has been linked to Raynaud's Disease

Prolonged exposure to the pronounced vibration conducted by the tool can lead to blood-circulation failures in the fingers, a condition known as 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, the Hilti TE 3000-AVR has approximately the same impact energy of a 60 lb pneumatic hammer, but the vibration felt by the operator is significantly less 7 meters per second squared 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 RCS19

Referencesedit

Air hose connection on pneumatic drill
  1. ^ STEAM OR PNEUMATIC ENGINE
  2. ^ https://booksgooglecouk/booksid=BQZRAAAAYAAJ&q=Samuel+Miller+Drill&dq=Samuel+Miller+Drill&hl=en&sa=X&ved=0ahUKEwiulfSosYbUAhUWOsAKHQsbBTIQ6AEIMTAC
  3. ^ https://booksgooglecouk/booksid=QKBhAAAAcAAJ&pg=PA39&dq=miller+1806+2926+patent&hl=en&sa=X&ved=0ahUKEwjur53ysYbUAhULJMAKHfSPBrYQ6AEIMjAC#v=onepage&q=miller%201806%202926%20patent&f=false
  4. ^ https://booksgooglecom/booksid=jo3HDnvu0rIC&pg=PA33&lpg=PA33&dq=Brunton+1844+Drill&source=bl&ots=D2lp0p6RMQ&sig=MZN7OKFaccsWbhfww3Hg7Z190Fc&hl=en&sa=X&ved=0ahUKEwj6jLLR29rNAhWN0RoKHUPeBL4Q6AEIJjAB#v=onepage&q=Brunton%201844%20Drill&f=false
  5. ^ Henry S Drinker,Tunneling, explosive compounds, and rock drills … New York, New York: John Wiley & Sons, 1878, pages 153-157
  6. ^ Drinker 1878, page 160
  7. ^ Drinker 1878, page 164
  8. ^ Drinker 1878, page 266
  9. ^ The project was called the "Mount Cenis tunnel" although the tunnel passed under Mount Fréjus
  10. ^ Drinker 1878, page 152
  11. ^ Drinker 1878, pages 168 and 266
  12. ^ Drinker 1878, pages 151-152
  13. ^ Drinker 1878, pages 169 and 266
  14. ^ 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
  15. ^ How It Works - Horobin, Wendy; Marshall Cavendish Corporation, Third Edition, Page 1195
  16. ^ Ellis, Iain 7 September 2006 Ellis' British Railway Engineering Encyclopaedia lulucom p 371 ISBN 9781847286437 Retrieved 17 February 2014 
  17. ^ https://booksgooglecom/booksid=FXOtwx6IK_0C&pg=PA240
  18. ^ Clint DeBoer "How’s It Work Rotary Hammers" Pro Tool Reviews Retrieved June 22, 2016 
  19. ^ "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

External linksedit

  • How jackhammers work
  • How Rotary Hammers Work

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    Jackhammer beatiful post thanks!

    29.10.2014


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