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REPAIR THE STRIKING END OF PISTON
The NPK piston is designed for maximum fatigue resistance to failure of the striking
face. The striking face can become indented and mushroomed when the hammer has
been used for a long time or operated with worn-out tool bushings. To repair the piston,
dress the tool striking end with a grinder.
MODEL
NEW d13 MINIMUM d14
inch mm inch mm
GH06 13 329 12.70 323
GH07 13.10 332 12.80 326
GH1 15.60 396 15.30 388
GH2/GHS2 16 406 15.70 398
GH3 17.90 454 17.50 444
GH4 21.40 544 21.00 534
GH6 23.50 598 23.10 588
MAIN BODY SLEEVES
REPAIR OF SLEEVE INSIDE DIAMETER
Scoring or galling may occur when the hammer has been used for a long period of time;
or operated with worn-out tool bushings, loose tie rods, overheated hydraulic system, or
contaminated hydraulic oil. If the sleeve has slight scratches or scoring, then repair by
polishing. Call NPK for detailed information.
If the sleeve is damaged from scoring or galling in the axial direction, the oil grooves
may be filled with metallic particles. The oil grooves must be cleaned or they will cause
additional scoring.
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