Hitachi NR 65AK Service Manual page 25

Air leakage points
(C) Nose (I)
(D) Nose (II)
(E) Control valve (I)
(F) Control valve (II)
(G) Cap
With control valve OFF
The O-Ring (S-70) [11] of the Cylinder
Plate [12] is abnormal (broken or
damaged).
The O-Ring (S-46) [13] of the Cylinder
[15] is abnormal (broken or damaged).
The seal surface of the Body Ass'y [18],
Cylinder Plate [12] or Cylinder [15] is
abnormal ( c or d portion).
The O-Ring [45] on Valve Piston (B)
[44] is abnormal (worn, broken or
damaged).
The lower O-Ring [42] on Valve Piston
(B) [44] is abnormal (worn, broken or
damaged).
The O-Ring (S-18) [41] on Valve
Bushing (B) [40] is abnormal (broken or
damaged).
The inside surface of the valve chamber
of the Body Ass'y [18] is abnormal.
The O-Ring [48] on Plunger (A) [47] is
abnormal (worn, broken or damaged).
Valve Bushing (A) [49] is abnormal
(sliding surface of Plunger (A) [47] is
deformed or scratched).
Gasket (B) [34] is damaged.
The Hex. Socket Hd. Bolt M5 x 16 [36] is loose.
Seal surface of the Body Ass'y [18] or the Cap [35] is abnormal (damaged,
deformed or flawed).
Possible cause
The O-Ring [13] of the Body Ass'y [18]
is abnormal (broken or damaged).
The Nylock High Tension Bolt M6 x 20
[21] is loose.
The seal surface of the Body Ass'y [18]
or the Nose [20] is abnormal (broken,
deformed or scratched).
The Piston Bumper [19] is abnormal
( e or f portion is damaged,
deformed or cracked).
Piston (H) [17] is abnormal (driver
blade or sealed face is deformed).
The f surface of the Body Ass'y [18]
is deformed.
The upper O-Ring [42] on Valve Piston
(B) [44] is abnormal (worn, broken or
damaged).
The Head Valve O-Ring [39] on Valve
Bushing (B) [40] is abnormal (broken or
damaged).
The top surface of the valve chamber of
the Body Ass'y [18] is abnormal ( g
portion).
The inside of the O-Ring [43] on Valve
Piston (B) [44] is abnormal (worn,
broken or damaged).
Plunger (A) [47] is abnormal (sliding
surface is deformed or scratched).
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With control valve ON