Hitachi NR 65AK, Service Manual

Page: 18 / 47

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Fig. 14
8-3. Operation Principle
(1) Before nailing: (Fig. 14 and Fig. 15)
1) When compressed air is fed to the main body,
it fills the accumulator ( ).
2) At the same time, the compressed air flows into
the valve piston lower chamber of the control
valve section and forces Valve Piston (B) [44]
upward. Also, the compressed air is fed through
the air supply vent and air passage to the head
valve chamber. As a result, the Head Valve
Spring [8] is pushed down together to seal
Head Valve (A) [10] and Cylinder [15].
(2) When nailing: (Fig. 14 and Fig. 15)
1) When Pushing Lever (A) [30] and Trigger [52]
are operated together and Plunger (A) [47] is
pushed upward, the compressed air in the valve
piston lower chamber is discharged from the
bottom of Plunger (A) [47]. As a result, the
compressed air in the accumulator ( ) pushes
down Valve Piston (B) [44], blocking the air
supply vent and opening the exhaust valve.
2) When the exhaust valve opens, the compressed
air in the head valve chamber is discharged into
the atmosphere through the air passage.
3) When the air pressure applied on the bottom
surface of Head Valve (A) [10] overcomes the
strength of the Head Valve Spring [8], Head
Valve (A) [10] is pushed upward. At this time,
Head Valve (A) [10] seals the Exhaust Cover [5],
blocking the passage to the exhaust vent.
4) When Head Valve (A) [10] goes up, the
compressed air in the accumulator flows rapidly
into the Cylinder [15], forcing Piston (H) [17]
downward to strike the nail. When Piston (H)
[17] passes the cylinder hole, the compressed air
flows into the return air chamber and is
accumulated there.
Fig. 15 Control valve section