Komatsu PC88MR-10 Shop Manual page 253

5. Fuse box
6. Resister for PC EPC valve
7. Pump controller
8. Engine controller
9. Machine monitor
10. Pump secondary drive switch
11. Fuel control dial
12. Fuel supply pump
13. Various sensors
14. Oil pressure sensor of pump
15. Oil pressure sensor
16. Oil pressure switch
17. Main pump
17a. Servo
17b. LS valve
17c. PC valve
18. Control valve
18a. Merge-divider valve
18b. Self-pressure reducing valve
19. PC-EPC valve
Input/output signal
a: CAN signal
b: PC-EPC valve drive signal
c: Solenoid valve GND
d: Oil pressure sensor signal
e: Oil pressure switch signal
f: Throttle signal
g: Fuel supply pump control signal
h: Various sensor signals
Function
This function allows the operator to select one from the 6 working modes of P, E, L, B, ATT-P, and ATT-E
by using the working mode selector switch on machine monitor (9).
The operator can select the most appropriate engine torque (T) and pump absorption torque according to
the contents of work.
If "Without Attachment" is set for the attachment by "With/Without Attachment" in "Default" of the service
mode, the available modes are 4 of P, E, L, and B.
Pump controller (7) calculates the pump absorption upper limit torque according to the engine speed set
with the working mode and fuel control dial (11) and the actual engine speed, and controls the pump so
that the engine speed is kept around the matching point set in each mode even when heavy load is
applied.
When the engine speed decreases, the pump controller reduces the pump absorption torque to prevent
the engine from stalling.
PC88MR-10
10 Structure and function
Electrical control system
10-175