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When the switch is set to L, the motor rotates
counterclockwise to loosen the bolt. When the switch
is released, the motor stops.
CAUTION
Be sure to turn the switch OFF and wait until the
motor completely stops before changing the
direction of wrench revolution. Switching while the
motor is rotating will result in burning the motor.
2. Tightening and loosening bolts
A hex socket matching the bolt or nut must first
be selected. Then mount the socket on the anvil,
and grip the nut to be tightened with the hex socket.
Holding the wrench in line with the bolt, press the
power switch to impact the nut for several seconds.
If the nut is only loosely fitted to the bolt, the bolt
may turn with the nut, therefore preventing proper
tightening. In this case, stop impact on the nut and
hold the bolt head with a wrench before restarting
impact, or manually tighten the bolt and nut to
prevent them slipping.
OPERATIONAL CAUTIONS
1. Confirm the line voltage (Fig. 4)
The available tightening torque is influenced by line
voltage. Reduced line voltage lowers the available
tightening torque.
For example, if you use a 220 V type wrench on
a 200 V line the available tightening torque will be
reduced to 70 to 90 %. When extending the power
cord, use an extension cord which is as short as
possible. When the line voltage is low and a long
extension cord is needed a step up transfomer
should be used. The relation between the line voltage
and the tightening torque are shown in the figures.
2. Do not touch the bumper or hammer case during
continuous operation
The bumper and hammer case become hot during
continuous screw tightening so be careful not to
touch them at that time.
3. Work at a tightening torque suitable for the bolt
under impact
The optimum tightening torque for nuts and bolts
differs with material and size of the nuts and bolts.
An excessively large tightening torque for a small
bolt may strech or break the bolt. The tightening
torque increases proportionally to the operating
time. Use the correct operating time for the bolt.
4. Selecting the socket to be matched to the bolt
Be sure to use a socket which is matched to the
bolt to be tightened. Using an improper socket will
result not only in insufficient tightening but also in
damage to the socket or nut.
A worn or deformed hex or square-holed socket will
not give an adequate tightness for fitting to the nut
or anvil, consequently resulting in loss of tightening
torque.
Pay attention to wear of socket holes, and replace
before further wear developes. Matching socket and
bolt sizes are shown in Table 1.
The numerical value of a socket designation denotes
the side to side distance (S) of its hex hole.
5. Holding the tool
Hold the Impact Wrench firmly with both hands by
the body handle and the side handle. In this case
hold the wrench in line with the bolt.
It is not necessary to push the wrench very hard.
Hold the wrench with a force just sufficient to
counteract the impact force.
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) Line voltage:
The tightening torque decreases when the line
voltage becomes low (See Fig. 4).
(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 (See Fig. 4).
(3) Diameter of bolt:
The tightening torque differs with the diameter of
the bolt as shown in Fig. 4. Generally a larger
diameter bolt has a 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 metal through which the bolts are to be
tightened.
(5) Using optional parts:
The tightening torque is reduced a little when an
extension bar, universal joint or a long socket is
used.
(6) Clearance of the socket:
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. Matching socket and bolt sizes are shown
in Table 1.
MAINTENANCE AND INSPECTION
1. Inspecting the socket
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
socket holes periodically, and replace with a new
one if needed.
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
For your continued safety and electrical shock
protection, carbon brush inspection and replacement
on this tool should ONLY be performed by a Hitachi
Authorized Service Center.
01Eng_WR16SA(S)_WE 4/7/10, 13:297