NPK GH1 - Maximum Tool to Tool Bushing Clearance; Clearance Measurement and Comparison

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MAXIMUM TOOL TO TOOL BUSHING
CLEARANCE
Replace the tool bushing upper (F) or lower (G), and/or tool (HH), when the tool to
bushing gap reaches the maximum clearance. To determine whether the bushing or
tool requires replacement, follow the instructions and charts shown below:
Step 1
Measure the tool to bushing gap (d15) with the hammer horizontal, as illustrated below.
If the clearance is at or greater than the charted maximum clearance, then move on to
the next steps.
MODEL
MAXIMUM CLEARANCE
INCH (mm)
GH06 1/4 (6.5)
GH07 1/4 (6.5)
GH1 1/4 (6.5)
GH2/GHS2 1/4 (6.5)
GH3 1/4 (6.5)
GH4 1/4 (6.5)
GH6 3/8 (10)
Step 2
Remove the tool from the tool holder. Measure the diameter (d16) of the bearing
surface of the tool, which is located on each side of the retaining pin groove. The
minimum tool diameter is compared to a new tool bushing only
. If the tool is at or below
the charted value, the tool must be replaced.
MODEL
NEW TOOL DIAMETER
INCH (mm)
MINIMUM TOOL DIAMETER
INCH (mm)
GH06 1.63 (41.4) 1.43 (36.4)
GH07 1.83 (46.6) 1.63 (41.4)
GH1 2.23 (56.6) 2.02 (51.4)
GH2/GHS2 2.58 (65.6) 2.38 (60.4)
GH3 2.98 (75.6) 2.81 (71.4)
GH4 3.37 (85.6) 3.2 (81.4)
GH6 4.16 (105.6) 3.8 (96.4)