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EMERGENCY BOOM LOWERING PROCEDURE
(Without hose-rupture safety valve)
WARNING: Prevent personal injury. Confirm that no
one is under the front attachment before starting the
procedure below.
ZX120-3 class
If the engine abnormally stalls and cannot be restarted,
lower the boom to the ground by following the emergency
procedures described below.
1. Remove rubber caps (1) and (2) from the boom-1 section
on the 4 spool control valve.
2. Turn lock nut (8) (with hexagonal width across flats: 17
mm) counterclockwise to remove with an offset box
wrench or a spanner.
3. Turn screw (7) (with hexagonal hole width across flats: 4
mm) clockwise with a hexagon wrench until it comes to
stop.
4. Turn lock nut (5) (with hexagonal width across flats: 17
mm) counterclockwise to slightly loosen with an offset
wrench or a spanner.
5. While turning screw (6) (with hexagonal width across
flats: 4 mm) clockwise with a hexagon wrench to ad-
just the boom lowering speed, lower the boom. Do not
remove snap ring (3) and washer (4) at this time. In addi-
tion, do not turn screw (6) to such extend as washer (4) is
deformed.
6. After the boom is lowered to the ground, allow screws
(6) and (7) to be fully loosened by turning them coun-
terclockwise. Then, turn screw (7) one eighth of a turn
clockwise and tighten lock nuts (5) and (8).
Tightening torque: 19.5 N•m (2 kgf•m)
NOTE: Unless lock nuts (5) and (8) are sufficiently tightened,
oil leakage may increase. Be sure to completely tighten
the lock nuts to the torque specified above.
7. Take care to correctly install rubber caps (1) and (2) in
their respective original position.
NOTE: Conduct the work of screw (7) and screw (6) in order.
OPERATING THE MACHINE
5-33
Base Machine Rear Side
1
2
Control Valve
7
2
8
Boom 1
M175-05-001
6
3
4
1
5
M154-05-001
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