Operation Principle - Hitachi NV 65AF3 Technical Data And Service Manual

8-2. Operation Principle

Air passage (A)
Head valve spring
Head valve
Cylinder
Pushing
lever (A)
Fig. 8 Prior to nailing
Head valve spring
Head valve
Cylinder
Cylinder hole
Piston
Air passage
(B)
[Return air
chamber]
Pushing
lever (A)
Fig. 9 During nailing (I)
Air supply vent
Accumulator
Valve piston (B)
Control
valve
section
Exhaust cover
Air passage (A)
Air supply vent
Exhaust valve
Accumulator
Valve piston
Plunger (A)
Trigger (A)
Pushing lever (B)
Nail feeder
section
Feed spring
Feed piston
Feeder
(1) Prior to nailing (see Fig. 8)
1. When compressed air is supplied to the main body,
it fills the accumulator (see diagram).
2. At the same time, the compressed air flows into the
valve piston lower chamber of the control valve
section, and pushes up the valve piston. Also, the
compressed air flows from the air supply vent,
through air passage (A), and into the head valve
upper chamber where it simultaneously pushes
down the head valve and the head valve spring to
seal the upper surface of the head valve and the
cylinder.
(2) During nailing (I) (see Fig. 9)
1. When plunger (A) is pushed up by operating both
the pushing lever and trigger (A), the compressed
air in the valve piston lower chamber is exhausted
from the lower part of plunger (A). Then, the valve
piston is pushed down by the compressed air from
the accumulator so that it shuts off the air supply
vent and releases the exhaust valve.
2. When the exhaust valve opens, the compressed air
in the head valve upper chamber is exhausted into
the atmosphere through air passage (A).
3. The air pressure applied against the lower surface
of the head valve soon exceeds the force of the
head valve spring, and pushes the head valve up.
The head valve is pushed fully upward by the
compressed air, and seals the upper surface of the
exhaust cover and the head valve.
4. When the head valve is pushed up, the
compressed air flows rapidly into the cylinder and
pushes down the piston to drive a nail. At this time,
the compressed air flows through the cylinder hole,
into the return air chamber, through air passage (B),
and into the chamber at the left side of the feed
piston in the nail feeder section. When the air
pressure exceeds the force of the feed spring, the
feeder moves to the right.
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