Hitachi NR 90AD (S), Technical Data And Service Manual

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Check if the driver blade tip
is worn.
Check nail feeder (A) for
abnormal condition.
Perform idle driving or
actually drive with nails, and
check if the driver blade has
returned completely.
O-ring in plunger is worn.
O-ring in valve piston is
worn.
Abnormal plunger sliding
surface of valve piston
(seized or deformed).
Abnormal plunger, trigger
arm (C), pushing lever (C)
and/or body (worn or
damaged).
The position of a switching
device is mistaken.
5) Single
actuation
mechanism is
not possible.
Disassemble the control
valve section, and check the
O-ring of the plunger and
the valve piston.
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.
Problem
Possible cause
Inspection method Remedy
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 O-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 O-ring and the inner/
outer surfaces of the
cylinder for abnormal
condition.
See <Magazine> in item 1).
Driver blade worn.
Nail feeder (A) is abnormal
(worn or damaged).
Check if they move
smoothly after putting nails,
and check if the nail feeder
operates smoothly.
See <Magazine> in item 1).
Replace the part.
Replace nail feeder (A).
See <Output section> in
item 1).
< Improper nail feed>
Unspecified nails used.
Check if the nails are
specified ones. Use specified nails.
4) Nails clog the
mechanism.
See <Output section> in
item 1).
< The driver blade has not
returned completely.>