Hitachi DH24PC Handling Instructions Manual page 22

LUBRICATION
Low viscosity grease is applied to this hammer drill so
that it can be used for a long period without replacing
the grease. Please contact the nearest authorized ser-
vice center for grease replacement when any grease is
leaking from a loosened screw.
Further use of the hammer drill with incorrect grease will
cause the machine inefficiency and reduce the service
life.
CAUTION:
A special grease is used with this machine, therefore, the
normal performance of the machine may be badly af-
fected by use of other grease. Please be sure to let one
of our authorized service center undertaking replace-
ment of the grease.
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 new ones or resharpen them without
delay when abrasion is noted.
2. Inspecting the mounting screws:
Regularly inspect all mounting screws and ensure
that they are properly tightened. Should any of the
screws be loose, retighten them immediately. Failure
to do so could result in serious hazard.
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. 21)
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 numbers
shown in Fig. 21.
In addition, always keep carbon brushes clean and
ensure that they slide freely within the brush holders.
5. Replacing a carbon brush (Fig. 22)
Disassembling
(1) Loosen the three screws on the handle cover, and
remove the handle cover.
(2) Lift out the brush holder together with the carbon
brush, while being very careful not to forcibly pull
the lead wires within the brush holder.
(3) Withdraw the brush terminal, and remove the carbon
brush from the brush holder.
Reassembling
(1) Place a new carbon brush into the brush holder, and
connect the brush terminal to the carbon brush.
(2) Return the brush holder and other parts to their
original positions, as illustrated in Fig. 22.
(3) Place the lead wire in the specified position. Be very
careful not to allow the lead wire to contact the
armature or rotating parts of the motor.
(4) Mount the handle cover, while being careful to ensure
it does not pinch the lead wire, and secure it firmly
with the three screws.
21
CAUTION
Should the lead wire be pinched by the handle cover
or come in contact with the armature or rotating
parts of the motor, a serious danger of electric shock
to the operator will be created. Excercise extreme
caution in disassembling and reassembling the motor,
following the above procedures exactly.
Do not attempt to disassemble any parts other than
those necessary to effect replacement of the carbon
brush.
NOTE:
Due to HITACHI's continuing program of research and
development, the specifications herein are subject to
change without prior notice.