Hitachi ZW180 Technical Manual page 58

Standard Torque Control
Purpose: To utilize engine output power by changing
pump delivery flow rate in response to in-
crease or decrease of engine speed and
hydraulic oil temperature effectively.
Operation:
1. When the accelerator pedal is depressed, MC
calculates the target engine speed.
2. MC calculates the pump maximum displacement
angle by receiving the target engine speed signal
and hydraulic oil temperature, and transmits the
signal to the pump torque control solenoid valve.
3. The pump torque control solenoid valve transmits
pilot pressure according to the signal to the main
pump regulator, and controls the pump delivery
flow rate.
NOTE: In case the pump torque control solenoid
valve becomes abnormal, standard torque
control is not made.
SYSTEM / Control System
T2-1-16
Q
Flow
Rate
P-Q Line
Pressure
P