Hitachi ZW180 Technical Manual page 136

Pump Control Circuit
(Refer to the COMPONENT OPERATION / Pump
Device group.)
•
Pump Control by Servo Piston Control Pressure
•
Servo piston control pressure (PS2) is supplied
from the charging block for actuation of the servo
piston of the main pump.
•
Pump Flow Control by Flow Control Pressure
(Pi1/Pi2)
•
Pressures upward and downward the orifice – Pi1
and Pi2 – of the pump flow control valve installed
at the farthest downstream of the control valve
neutral circuit are supplied to the main pump
regulator in order to adjust the pump flow.
•
Pump Flow Control by Pump Torque Control
Solenoid Valve
•
The signal from MC actuates the pump torque
control solenoid valve, and controls pilot pressure
(X) supplied to the main pump regulator in order
to control the pump flow.
SYSTEM / Hydraulic System
T2-3-20