Hitachi WH 12D Handling Instructions Manual page 43

Bolt
Nut
Kg–cm
1600
1200
800
400
0
(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. 9, 10 and 11)
(3) Diameter of bolt
The tightening torque differs with the diameter of
the bolt as shown in Fig. 9, 10 and 11. Generally
a larger diameter bolt has 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. When the bolt and nut turn together,
torque is greatly reduced.
(5) Using optional parts
The tightening torque is reduced a little when an
extension bar, universal joint or a long socketis
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 and 2.
Steel plate thickness t
Fig. 12
M14 × 50 High tensile bolt (tightening time 3 sec)
When completely recharged
When completely discharged
0 20
Number of tightenings (PCS)/charging
*The following bolt is used.
Ordinary bolt: Hardness division 4.8
High tensile bolt: Hardness division 12.9
40 60
Fig. 13
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
a 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. Fail-
ure to do so may result in serious hazard.
3. Cleaning of the outside
When the impact driver is stained, wipe with a soft
dry cloth or a cloth moistened with soapy water.
Do not use chloric solvents, gasoline or paint thinner,
for they melt plastics.
4. Storage
Store the impact driver in a place in which the
temperature is less than 40°C, and out of reach of
children.
NOTE
Due to HITACHI's continuing program of reserch and
development, the specifications herein are subject to
change without prior notice.
English
a
80
41