Maintenance And Inspection - Hitachi WH 9DMR Handling Instructions Manual

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6. Confirm the tightening torque
The following factors contribute to a reduction of the
tightening torque. So confirm the actual tightening
torque needed by screwing up some bolts before the
job with a hand torque wrench. Factors affecting the
tightening torque are as follows.
(1) Voltage
When the discharge margin is reached, voltage
decreases and tightening torque is lowered.
(2) Operating time
The tightening torque increases when the operating
time increases. But the tightening torque does not
increase above a certain value even if the tool is
driven for a long time.
(3) Diameter of bolt
The tightening torque differs with the diameter of the
bolt. Generally a larger diameter bolt requires larger
tightening torque.
(4) Tightening conditions
The tightening torque differs according to the torque
ratio; class, and length of bolts even when bolts with
the same size threads are used. The tightening torque
also differs according to the condition of the surface
of workpiece through which the bolts are to be
tightened. When the bolt and nut turn together, torque
is greatly reduced.
(5) Using optional parts (Impact wrench)
The tightening torque is reduced a little when an
extension bar, universal joint or a long socket is used.
(6) Clearance of the socket (Impact wrench)
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.
Using an improper socket which does not match to
the bolt will result in an insufficient tightening torque.

MAINTENANCE AND INSPECTION

1. Inspecting the driver bit (Impact driver)
Using a broken bit or one with a worn out tip is
dangerous because the bit can slip. Replace it.
2. Inspecting the socket (Impact wrench)
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. 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 may result in serious hazard.
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. 13)
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" P. In addition, always keep
carbon brushes clean and ensure that they slide freely
within the brush holders.
11
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 R with a slotted head screw driver,
etc., as shown in Fig. 15.
When installing the carbon brush, choose the direction
so that the nail of the carbon brush Q agrees with the
contact portion outside the brush tube S. Then push
it in with a finger as illustrated in Fig. 16. Lastly,
install the brush cap.
CAUTION
Be absolutely sure to insert the nail of the carbon
brush into the contact portion outside the brush tube.
(You can insert whichever one of the two nails
provided.)
Caution must be exercised since any error in this
operation can result in the deformed nail of the carbon
brush and may cause motor trouble at an early stage.
7 Cleaning of the outside
When the impact driver and impact wrench are
stained, wipe with a soft dry cloth or a cloth moistened
with soapy water. Do not use chloric solvents, gasoline
or paint thinner, as they melt plastics.
8. Storage
Store the impact driver and impact wrench in a place
in which the temperature is less than 40°C, and out of
reach of children.
9. Service parts list
CAUTION
Repair, modification and inspection of Hitachi Power
Tools must be carried out by a Hitachi Authorized
Service Center.
This Parts List will be helpful if presented with the
tool to the Hitachi Authorized Service Center when
requesting repair or other maintenance.
In the operation and maintenance of power tools, the
safety regulations and standards prescribed in each
country must be observed.
MODIFICATIONS
Hitachi Power Tools are constantly being improved
and modified to incorporate the latest technological
advancements.
Accordingly, some parts may be changed without
prior notice.
GUARANTEE
We guarantee Hitachi Power Tools in accordance with
statutory/country specific regulation. This guarantee does
not cover defects or damage due to misuse, abuse, or
normal wear and tear. In case of complaint, please send
the Power Tool, undismantled, with the GUARANTEE
CERTIFICATE found at the end of this Handling
instruction, to a Hitachi Authorized Service Center.
NOTE
Due to HITACHI's continuing program of research and
development, the specifications herein are subject to
change without prior notice.