OPERATING THE MACHINE
5-18
SECONDARY RELIEF PRESSURE
ADJUSTMENT
When attaching the breaker other than the NPK, it is nec-
essary to install the secondary relief valve in line. For this
purpose, the boom piping for the attachment is provided
with a part to which the secondary relief valve is con-
nected.
Pressure is set to 10.0 MPa (100 kgf/cm
2
) when shipped
from HITACH.
After completing piping, reset this pressure to the specified
level of each breaker.
Adjust the pressure as follows :
1. Attach the pressure gauge to the pressure gauge
port.
2. Loosen the lock nut, then gradually turn the pres-
sure-adjust screw clockwise to increase the pressure,
or counterclockwise to reduce the pressure.
One turn of the screw changes about 5.0 MPa (50
kgf/cm
2
) in pressure.
3. After adjusting the pressure, make sure to tighten the
lock nut.
Two methods are available to measure the pressure.
Measure the pressure as follows.
1. Measuring the pressure at the relief valve :
(1) Attach a pressure gauge to the pressure
gauge connection port (see the figure be-
low)
(2) Close the stop valves at the arm end.
Depress the attachment pedal to pressure
the line.
(3) Adjust the pressure to 1 to 1.5 MPa (10 to
15 kgf/cm
2
) higher the setting pressure.
M107-05-005
2. Measuring the pressure at the arm end.
(1) Remove the attachment connection horse and
connect a pressure gauge to the connection fit-
ting at the arm end.
(2) Adjust the pressure to the setting pressure.
(WIDTH ACROSS FLAT : 14)
PRESSURE-ADJUST
BOLT
(PT 1/4)
PRESSURE GAUGE
CONNECTION PORT
LOCK NUT
(WIDTH ACROSS FLAT : 14)
PRESSURE DECREASE PRESSURE INCREASE
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