Hitachi ZW180 Technical Manual page 194

Regulator Control Function
Regulator has the following three control functions.
•
Control by Pump Control Pressure
The pump flow control valve inside the control valve
controls pump control pressure (Pi1 - Pi2) in
response to the operating stroke of the control lever.
The regulator increases or decreases the pump
delivery flow in response to the pressure by
receiving this pump control pressure (Pi1 - Pi2).
When the control lever is operated, pump control
pressure (Pi1 - Pi2) lowers, and the regulator
increases the pump delivery flow. If the control lever
is returned to neutral, pump control pressure (Pi1 -
Pi2) rises, and the regulator decreases the pump
delivery flow.
•
Control by Own Pump Pressure
Own pump pressure Pd1 enters the regulator. In
case this pump pressure exceeds the set P - Q line,
the pump delivery flow is decreased and the
pressure returns to the P - Q line.
•
Control by Pilot Pressure from Torque Control
Solenoid Valve
MC (main controller) makes arithmetic operations of
the operating conditions of the vehicle body, and
transmits the signals to the pump torque control
solenoid valve in order to obtain required pump
torque.
The pump torque control solenoid valve transmits
pump torque control pressure ST corresponding to
this signal to the regulator. The regulator decreases
the pump delivery flow by receiving the pilot
pressure.
COMPONENT OPERATION / Pump Device
Flow (Q)
0
Flow (Q)
0
Flow (Q)
0
T3-1-6
Pump Control Pressure (Pi1-Pi2)
Pressure Increase
Flow Rate Decrease
Pressure (P)
Pressure (P)