Fiat Kobelco EX355 Tier2, Technical Manual

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T3-3-16 EX355
CONTROL VALVE
ARM REGENERATIVE VALVE
The arm regenerative valve regulates the return oil
flow from the cylinder rod side when rolling the arm in.
Thereby, the arm roll-in speed is increased to improve
the arm controllability so that the arm hesitation is
prevented.
When the arm is rolled in, pump 2 delivery pressure is
low, and arm roll-in pilot pressure is high, solenoid
valve (SC) supplies the pilot pressure to the control
valve.
Then, the pilot pressure is routed to port SC and the
arm regenerative valve is activated. (Refer to the
Control System group in the SYSTEM section.)
The return oil from the arm cylinder flows into the
spool via arm spool port (a). When the arm regenera-
tive valve is in neutral, the pressure oil from port (a)
flows to the hydraulic oil tank via port (b) and orifice A.
When the pilot pressure oil is supplied from port SC,
the arm regenerative valve is activated. Then, the
pressure oil flow from port (a) is restricted by orifice A
and port (c) increasing the pressure in the spool. If the
pressure in the arm cylinder bottom side is lower than
the spool inside, the pressure in the spool opens the
check valve and flows into the arm cylinder bottom
circuit via port (d).
When the arm regenerative valve is in neutral:
When the arm regenerative valve is operated:
SM6063
Orifice A
Port (a)
Arm
Regenerative
Valve
To the
Hydraulic
Oil Tank.
Port (b)
Port (c) (Orifice)
Orifice B
SM6065
Orifice A
Port (a)
Arm
Regenerative
Valve
To the
Hydraulic
Oil Tank.
Port (b)
To the Cylinder
Bottom Side
Circuit.
Port (d)
Check Valve
Pilot Pressure
from Solenoid
Valve Unit (SC)
SM6064
Arm
Regenerative
Valve
Orifice A
Port (b), Port (c)
From the
4-Spool Section
Neutral Circuit.
Port (b)
Check Valve
From the
4-Spool Section
Parallel Circuit.
Arm
Cylinder
Port (a)
Port (d)
To the Hydraulic
Oil Tank.
SC
Arm 2 Spool