Komatsu ecot3 PC300LC-8 Shop Manual page 114

SEN01993-00
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)
q Command current (X) is being sent to PC-EPC
valve solenoid (1) from the pump controller.
q This command current acts on PC-EPC valve
to output the signal pressure in order to modify
the force pushing piston (2).
q Spool (3) stops at a position where the com-
bined spool-pushing force is balanced by the
setting force of springs (4) and (6) as well as
the pump pressures (PP1) (self-pressure) and
(PP2) (another pump's pressure).
q The pressure [port (C) pressure] output from
PC valve is changed depending on the above
position.
q The size of command current (X) is determined
by the nature of the operation (lever opera-
tion), the selected working mode, and the set
value and actual value of the engine speed.
18
10 Structure, function and maintenance standard
a Other pump's pressure denotes the pressure
of the pump situated on the opposite side.
For the front pump pressure, the other pump's
pressure is that of the rear pump.
And for the rear pump pressure, the other
pump's pressure is that of the front pump.
PC300, 350-8