Komatsu Galeo PC138US-8 Shop Manual page 120

SEN02548-01
Operation
1. When pump controller is normal
1) When the load on the actuator is small and pump discharge pressures (PP1) and (PP2) are low
Action of PC-EPC valve solenoid (1)
Command current (X) is being sent to PC-EPC
q
valve solenoid (1) from the pump controller.
This command current acts on PC-EPC valve
q
to output the signal pressure in order to modify
the force pushing piston (2).
Spool (3) stops at a position where the com-
q
bined spool-pushing force is balanced by the
setting force of springs (4) and (6) as well as
the pump pressures (PP1) (check valve output
pressure) and (PP2) (shuttle valve output pres-
sure).
20
10 Structure, function and maintenance standard
The pressure [port (C) pressure] output from
q
PC valve is changed depending on the above
position.
The size of command current (X) is determined
q
by the nature of the operation (lever opera-
tion), the selected working mode, and the set
value and actual value of the engine speed.
PC138US, USLC-8