NPK PH4 - Tool Breakage Due to Excessive Wear of the Tool Holder Bushings

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TOOL BREAKAGE
TOOL BREAKAGE DUE TO EXCESSIVE WEAR OF THE TOOL
HOLDER BUSHINGS
If the hydraulic hammer is used with tool holder bushings worn beyond specifications,
the tool will be at an excessive angle to the piston at the moment of impact. The entire
force of the piston is concentrated in a small area of the impact head of the tool (Fig. 1).
This results in the impact head being chipped or broken (Fig. 2 & 3). With the tool at an
angle, and in excessive side loading contact with the tool holder bushings, the shock
load traveling down the tool is unevenly concentrated (Fig. 1). This can result in the tool
breaking through the retaining pin slot (Fig. 4).