Hitachi NT 65MA3, Service Manual

Page: 16 / 37

--- 13 ---
(4) Single actuation mechanism/contact actuation mechanism: (Fig. 9 and Fig. 10)
Single/contact actuation mechanism changeover is accomplished by turning the switching device
(Change Knob [57] ).
Single actuation mechanism (Switching device:
upward position):
1) Immediately after driving the first nail, the control
valve should be as shown in Fig. 8.
2) When only Pushing Lever (B) [36] is released
and Trigger (A) [53] is held as shown in Fig. 9,
the plate of Trigger (A) [53] contacts the Change
Knob [57] and Plunger (A) [68] returns (lowers)
only halfway.
Because of this, compressed air does not flow
into the valve piston lower chamber, and Valve
Piston (B) [65] remains in the lowered position.
Accordingly, the Piston [15] remains in the
lowered position as shown in Fig. 7.
3) When Trigger (A) [53] is released, Plunger (A)
[68] returns (lowers) completely as shown in
Fig. 6. Compressed air then flows into the valve
piston lower chamber, and Valve Piston (B) [65]
is forced upward. The Piston [15] then returns
fully upward. Therefore, unless Trigger (A) [53]
is released after each nailing operation, the
structural mechanism prevents the next nailing
operation.
Contact actuation mechanism (Switching device:
downward position):
1) Immediately after the first nail is driven, the
control valve should be as shown in Fig. 8.
2) Even when only Pushing Lever (B) [36] is
released and Trigger (A) [53] is held, Plunger
(A) [68] returns (lowers) completely as shown in
Fig. 10. Thus the Piston [15] returns (raises)
fully. Accordingly, continuous nailing can be
accomplished by pushing only Pushing Lever
(B) [36] up and down while holding Trigger (A)
[53] depressed.
Accumulator
Switching device (Change Knob [57] )
(upward position)
Plate
Valve Piston (B) [65]
Trigger (A) [53]
Pushing Lever (B) [36]
Plunger (A) [68]
Fig. 9 Single actuation mechanism
Accumulator
Switching device (Change Knob [57] )
(upward position)
Valve piston
lower chamber
Valve Piston (B) [65]
Trigger (A) [53]
Pushing Lever (B) [36]
Plunger (A) [68]
Fig. 10 Contact actuation mechanism
Valve piston
lower chamber