Hitachi NV 65AF3 Technical Data And Service Manual page 18

Cylinder
Cylinder hole
[Return air
chamber]
Piston
Air passage (C)
Fig. 10 During nailing (II)
Head valve spring
Head valve
Cylinder
Piston
[Return air
chamber]
Air passage (C)
Fig. 11 During return
Feed piston
Nail feeder
Air passage (A)
Air supply vent
[Accumulator]
Valve piston
Plunger (A)
Trigger
Feed spring
Feed piston
Nail feeder
--- 15 ---
(3) During nailing (II) (see Fig. 10)
1. When the piston moves down inside the cylinder,
the air below the piston flows through air passage
(C) under the cylinder and is accumulated in the
return air chamber together with the compressed air
flowing through the cylinder hole.
2. When the compressed air in the left chamber of the
feed piston moves the feed piston fully to the right,
the nail feeder (feed pawl) engages the next nail.
(4) After nailing (see Fig. 11)
1. When the trigger is released, the plunger goes
down, the air supply vent opens, the valve piston
goes up, and the compressed air in the
accumulator passes through air passage (A) into
the head valve upper chamber. The head valve is
then pushed down by the head valve spring and the
air pressure against the upper surface of the head
valve. At the same time, the exhaust valve opens
and the upper chamber of the cylinder is opened to
the atmosphere.
2. When the head valve seals the upper surface of the
cylinder, the compressed air accumulated in the
return air chamber passes through air passage (C),
presses on the lower surface of the piston, and
forces the piston to return upward to its original
position. Also, the compressed air above the piston
is exhausted through the head valve hole.
3. The compressed air accumulated in the left
chamber of the feed piston passes through air
passage (B), goes into the return air chamber, and
is then exhausted through the nose hole. The feed
piston is then moved to the left by the force of the
feed spring, and the feed pawl feeds the next nail
into the ejection port. This completes one full
nailing cycle.