Hitachi 120-3 class User Manual

OPERATING THE MACHINE
5-18
SECONDARY RELIEF PRESSURE ADJUSTMENT
When attaching the breaker other than the NPK, it is necessary
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 connected.
Pressure is set to A when shipped from HITACHI.
Model Set Pressure A
ZX120-3, 180-3, 200-3 class
ZX250LC-3, 250LCN-3
17.6 MPa (180 kgf/cm
2
)
ZX280LC-3, 280LCN-3
ZX330-3 class
19.6 MPa (200 kgf/cm
2
)
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 pressure-
adjust screw clockwise to increase the pressure, or coun-
terclockwise to reduce the pressure.
One turn of the screw changes about 4.9 MPa (50 kgf/
cm
2
) in pressure.
3. After adjusting the pressure, make sure to tighten the
lock nut.

Hitachi 120-3 class Specifications

General

Brand	Hitachi
Model	120-3 class
Category	Excavators
Language	English