Maintenance And Inspection - Hitachi WH 14 Instruction Manual

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(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 Figs. 5, 6, 7, 8 and 9)
(3) Diameter of bolt:
The tightening torque differs with the
diameter of the bolt as shown in Figs. 5, 6,
7, 8 and 9. 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 Tables 1 and 2.

MAINTENANCE AND INSPECTION

WARNING:
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 lossened, retighten them immediately.
WARNING:
16
Be sure to switch power OFF and disconnect the plug from the receptacle
during maintenance and inspection.
Using this impact wrench with loosened screws is extremely dangerous.
(WH22)
M20 70 (F10T)
70
(kg-m)
Rating
115V
60
50
40
30
20
0
0 2 4
Tightening time
Fig. 9
105V
(s)
6 8 10