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You know the drill!

Written by  Author |   Fri, 26 August 2016 05:05

 

Jackhammers or pneumatic drills were developed in response to the needs of mining, quarrying, excavating, and tunneling. They are usually used to break up rock, pavement, and concrete. 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.
 
A jackhammer (pneumatic drill or demolition hammer) is a pneumatic or electro-mechanical tool that combines a hammer directly with a chisel. 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. 
 
A jackhammer operates by driving an internal hammer up and down. The hammer is first driven down to strike the back of the bit and then back up to return the hammer to the original position to repeat the cycle. The bit usually recovers from the stroke by means of a spring. The effectiveness of the jackhammer is dependent on how much force is applied to the tool.
 
A jackhammer uses compressed air as the power source. The air supply usually comes from a portable air compressor driven by a diesel engine. 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.
 
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 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.
 
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. 
 
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.
 
DeWalt, Ingersoll Rand, Atlas Copco, Bosch, Hilti, Makita and Hitachi are among the bestselling pneumatic drills.
 
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