TM 5-3805-281-10
compression on opposite sides of the tool. The surface crack then grows in a series
of concentric rings until the section weakens and can no longer support the stresses
imposed. Complete failure occurs at this time.
* Stress per blow is not as critical as the frequency of blows. The stress level in the tool
becomes more critical with higher blows per minute and changes in the blows per
minute.
* For the same phenomena, longer tools at equal energy and frequency bear more stress
than shorter ones.
* Breakers working at higher frequencies must be lubricated more often due to the
above-mentioned stress on the tool as well as the thermal damage created by the
friction of the tool and lower bushing.
* Matching a small breaker to a carrier larger than hammer specification creates high
stress conditions on the tool.
* Operators are not always skillful in using the breaker. Visibility problems, site condi-
tions and the use of the point to move materials can set up surface fractures in the
tool. Breakage may not occur immediately but the conditions are now in place for a
future failure.
METHOD TO REDUCE THESE EFFECTS & INCREASE TOOL LIFE
* To drastically reduce the undesirable stresses on the tool, the breaker should be posi-
tioned perpendicular to the material to be worked. Slight arching-in of the hammer
toward the operator while firing and following the progression of the tool into the
material will deliver uniform pressure on the bushing in the contact areas. This will also
allow the lubricating grease to flow around and cool the tool, thus avoiding seizures,
micro-welding, and the creation of localized hot spots detrimental to the heat-treating
of the tool.
* All attempts must be made to eliminate prying with the tool or moving the carrier while
the weight is on the tool. Do not pivot the carrier on the tool!
* Overheating of the tool should be avoided on the point or chisel end. This occurs when
the tool works in an area longer than 30 seconds, creating a "dust pocket" between
the tool and hard material.
* The tool should be constantly lubricated with INDECO Supreme 1000 grease. You can
never over-grease the lower end of the breaker!! Attention to this fact will add longev-
ity to your tool and bushing life.
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