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PISTON TO SLEEVE RUNNING CLEARANCES
The clearances shown below are to be used in determining if the internal components of
the hammer are reusable. Measure the inside diameter of the sleeve and subtract the
outside diameter of the piston at each location shown. Note, in the NPK Hydraulic
Hammer Service Manual, the drawing of a piston shown in the piston repair section.
There are three critical surfaces marked d10, d12, and d11. Each surface has a
corresponding “Land” in the “A” or “B” sleeve through which the piston rides. These
lands can be recognized by the multiple oil control grooves.
If the measurements are smaller than the values shown in the chart below, the piston
and sleeves are reusable. If any of the measurements exceed the values shown, call
the NPK Service Department at 800-225-4379, for recommendations on parts
replacement.
MODEL
d10
in mm
d11
in mm
d12
in mm
GH06
.010 .25 .010 .25 .004 .11
GH07
.010 .25 .010 .25 .004 .11
GH1
.010 .25 .010 .25 .004 .11
GH2/GHS2 .010 .25 .010 .25 .004 .11
GH3
.010 .25 .010 .25 .004 .11
GH4
.010 .25 .010 .25 .004 .11
GH6
.010 .25 .010 .25 .006 .15