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27
MAINTENANCE AND INSPECTION
CAUTION: Pull out battery before doing any inspection or maintenance.
1. Checking the condition of the bit (WH12DM2, WH9DM2)
The bits should be checked regularly. If worn or broken bits can slip or decrease the
efficiency of the motor and burn it out.
Replace worn bits with new ones.
CAUTION: If you use a driver bit of which point is worn or broken, it will be dangerous
since it slips. So replace it with a new one.
2. Checking the condition of the socket (WR12DM2, WR9DM2)
A worn or deformed hex. or a square-holed socket will not give an adequate tightness
to the fitting between the nut or anvil, consequently resulting in loss of tightening
torque. Pay attention to wear of a socket holes periodically, and replace with a new one
if needed.
3. Check the Screws
Loose screws are dangerous. Regularly inspect them and make sure they are tight.
CAUTION: Using this power tool with loosened screws is extremely dangerous.
4. 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.
5. Inspecting the carbon brushes (Fig. 24)
The motor employs carbon brushes which are
consumable parts. Since and excessively worn
carbon brush can result in motor trouble, replace
the carbon brush with new ones when it becomes
worn to or near the “wear limit”. In addition,
always keep carbon brushes clean and ensure that
they slide freely within the brush holders.
NOTE: When replacing the carbon brush with a new
one, be sure to use the Hitachi Carbon Brush
Code No. 999054.
6. Replacing carbon brushes
Take out the carbon brush by first removing the
brush cap and then hooking the protrusion of the
carbon brush with a flat head screw driver, etc.,
as shown in Fig. 26.
When installing the carbon brush, choose the
direction so that the nail of the carbon brush
agrees with the contact portion outside the brush
tube. Then push it in with a finger as illustrated in
Fig. 27. Lastly, install the brush cap.
Fig. 24
Fig. 26
Wear limit
Nail of carbon brush
Protrusion
of carbon
brush
0.12" (3mm)
0.45"
(11.5mm)
Fig. 25