Jackhammers

August 7, 2008 by  


ibntufail

A pneumatic drill or jackhammer is a portable percussive drill powered by compressed air. It is used to drill rock, break up pavement, and more. It works like a hammer and chisel, by jabbing with its bit, not rotating.

A drill driven by compressed air, which rotates its cutting bit is called an air-drill or familiarly, a windy-drill or rotary hammer.

The word jackhammer is used in North American English and in Australia, and pneumatic drill is used colloquially elsewhere in the English speaking world, although the word (road) “breaker” is used in the trade.

The portable pneumatic jackhammer is impractical for use on walls and steep slopes, as it relies on the inertia of the mass of its body to drive the bit into the work, and manipulating that mass when not supported by the work is difficult. Also, gravity is required to bring the mass back into contact with the work after each blow. Though it is unhealthy practice, the operator may lean on the tool to assist but is not really capable of overcoming the forces involved when not assisted by gravity. A technique developed by experienced laborers is the use of two man teams to overcome this obstacle of gravity. One laborer 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 ones head.

Its pneumatic hose connections are designed so that any hose will connect with any other hose without attention to male and female hose-ends. see Gender of connectors and fasteners.A hydraulic jackhammer, 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. In mining, it is possible to use this against a vertical wall as the machine can be braced against the opposite wall of the gallery or some comparable device. Pneumatic tools are likely to be used in underground coal mines due to safety concerns.

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