Pump Torque Control Proportional Solenoid Valve - Hitachi ZW180 Technical Manual

PUMP TORQUE CONTROL PROPORTI-
ONAL SOLENOID VALVE (REFER TO THE
PILOT CURCUIT IN THE SYSTEM / HY-
DRAULIC SYSTEM GROUP.)
Pilot pressure supplied to the main pump regulator for
the pump delivery flow rate control is controlled by the
operation of the pump torque control proportional so-
lenoid valve.
1. When there is no signal from MC (Main Control-
ler), the spool of the solenoid valve is pushed by
the spring.
2. Pilot pressure oil is supplied to port ST in the main
pump regulator through port X.
3. When the signal is transmitted from MC, the spool
moves toward the spring in response to the signal
value and the amount of pilot pressure oil through
port X is lowered.
4. When the signal from MC becomes the maximum
value, the spool fully moves toward the spring and
pilot pressure oil is blocked by the spool.
5. As port X and port DR2 are connected, pilot
pressure oil at port X is lost.
COMPONENT OPERATION / Charging Block
Not in Operation of Solenoid Valve
(Section U-U)
In Operation of Solenoid Valve
(Section U-U)
T3-7-8
To Main Pump
Regulator
Port X
Port X
Spool
Spring
Pilot Pressure Oil
T4GB-03-06-009
Port
DR2
Spring
Pilot Pressure Oil
T4GB-03-06-010