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15
MAINTENANCE AND INSPECTION
WARNING: Be sure to switch power OFF and disconnect the plug from the
receptacle during maintenance and inspection.
1. Inspecting the drill bits
Since use of a dull tool will cause motor malfunctioning and degraded efficiency, replace
the drill bit with a new one or resharpening without delay when abrasion is noted.
2. Inspecting the screws
Regularly inspect all screws and ensure that they are properly tightened. Should any of
the screws be loose, retighten them immediately.
WARNING: Using this Rotary Hammer with loosen screws is extremely dangerous.
3. Maintenance of the motor
The motor unit winding is the very “heart” of the power tool. Exercise due care to
ensure the winding does not become damaged and/or wet with oil or water.
4. Inspecting the carbon brushes: (Fig. 17)
The motor employs carbon brushes which are consumable parts. When they become
worn to or near “wear limit”, it could result in motor trouble. When an auto-stop carbon
brush is equipped, the motor will stop automatically. At that time, replace both carbon
brushes with new ones which have the same carbon brush Nos. shown in the figure.
In addition, always keep carbon brushes clean and ensure that they slide freely within
the brush holders.
CAUTION:
Using this Rotary Hammer with a carbon brush which is worn in excess of the wear
limit will damage the motor.
Fig. 17
NOTE: Use HITACHI carbon brush No. 71 indicated in Fig. 17
Wear limit
No. of carbon brush
0.28" (7 mm)
0.67" (17 mm)
71
01Eng_DH50SB_US 25/5/07, 17:0015