Operational Cautions - Hitachi WH 14DMR Mode D'emploi

CAUTION:
●
In the work of the save mode (S), avoid the continuous screw-tightening as temperature of electronic
components of the converter switch increases.
11. Tightening and loosening screws
Install the bit that matches the screw, line up the bit in the grooves of the head of the screw, then tighten it.
Push the impact driver just enough to keep the bit fitting the head of the screw.
CAUTION:
●
Applying the impact driver for too long tightens the screw too much and can break it.
●
Tightening a screw with the impact driver at an angle to that screw can damage the head of the screw and
the proper force will not be transmitted to the screw.
Tighten with this impact driver lined up straight with the screw.
12. 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 mistaking 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. Resting the unit after continuous work
After use for continuous bolt-tightening work, rest the unit for 15 minutes or so when replacing the battery.
The temperature of the motor, switch, etc. will rise if the work is started again immediately after battery
replacement, eventually resulting in burnout.
CAUTION:
Do not touch the protector, as it gets very hot during continuous work.
2. Cautions on use of the speed control switch
This switch has a built-in, electronic circuit which steplessly varies the rotation speed. Consequently, when
the switch trigger is pulled only slightly (low speed rotation) and the motor is stopped while continuously
driving in screws, the components of the electronic circuit parts may overheat and be damaged.
3. Use a tightening time suitable for the screw
The appropriate torque for a screw differs according to the material and size of the screw, and the material
being screwed etc., so please use a tightening time suitable for the screw. In particular, if a long tightening
time is used in the case of screws smaller than 5/16" (8 mm), there is a danger of the screw breaking, so
please confirm the tightening time and the tightening torque beforehand.
4. Work at a tightening torque suitable for the bolt under impact
The optimum tightening torque for nuts or bolts differs with material and size of the nuts or bolts. An
excessively large tightening torque for a small bolt may stretch or break the bolt. The tightening torque
increases in proportionate to the operation time. Use the correct operating time for the bolt.
5. Holding the tool
Hold the impact wrench firmly with both hands. 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) 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.
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