Hitachi NR 90AC3, Technical Data And Service Manual

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Problem
Possible cause
Inspection method Remedy
For short nails, the adjuster
is raised too high.
Nails are not fully fed into
the injection port.
Unspecified nails are used.
Driver blade is worn.
Workpiece is very hard.
2) Nails are bent
when being
driven.
Check if the adjuster is
raised too high.
See item 1).
Check if the driver blade tip
is abnormally worn.
Drive a nail into soft wood
workpiece and check if the
nail is bent.
Turn the adjuster to the
lower position to decrease
the pressure.
See item 1).
Replace the driver blade.
Do not use unspecified
workpieces.
Adjust the adjuster to the
proper position.
Adjust for 5 to 8.5 kgf/cm
2
.
Do not use unspecified
workpieces.
Replace the driver blade.
Replace the defective part.
Adjuster is improperly
adjusted.
Air pressure is too low.
Workpiece is very hard.
Driver blade is worn.
Piston ring is abnormal
(worn or damaged).
Cylinder's internal surface is
abnormal (worn or rough).
3) Head of a nail
driven into a
workpiece
protrudes
from the wood
surface. Turn the adjuster to the
lowest position and drive a
nail.
Drive a nail into soft wood
workpiece and check if the
head protrudes from the
wood surface.
Operate the nailer without
nails and check if the driver
blade is projected from the
nose tip.
Disassemble the output
section and check the
piston ring, O-ring and the
inner/outer surfaces of the
cylinder for abnormal
condition.
O-ring in plunger (A) is
worn.
O-ring in valve piston (B) is
worn.
Abnormal plunger (A) sliding
surface of valve piston (B).
(seized or deformed)
Abnormal plunger (A),
trigger arm (A), pushing
lever (B) and/or body (worn
or damaged).
The position of a switching
device is mistaken.
4) Single
actuation
mechanism is
not possible.
Disassemble the control
valve section, and check the
O-ring of plunger (A) and
valve piston (B).
Check each part for
abnormalities (worn,
damaged, deformed, etc.).
The position of a switching
device is checked.
Replace the part.
Replace the part.
Replace the part.
Replace the abnormal part.
A switching device is set to
the correct position.