Komatsu PC500LC-10R, Shop Manual, Page: 307 / 758

2.
Spool (2) is pressed to the left by the spring (3).
3.
Port (P) is closed, and the pressurized oil from the self-pressure reducing valve does not flow to the control
valve.
4.
The pressurized oil from the control valve flows through port (C) and port (T), and drained into the tank.
When signal current is minute (coil is energized)
A E P 2 1 6 3 7
1.
When minute signal current flows through coil (4), coil (4) is energized, and the thrust force to the right is
generated in plunger (5).
2.
The push-pin (6) pushes spool (2) to the right, and the pressurized oil from port (P) flows into port (C).
3.
When the pressure at port (C) increases, combined force on surface (a) of spool (2) and the reaction force
of spring (3) becomes larger than the thrust of plunger (5).
4.
The spool (2) is pushed to the left, and port (P) and port (C) are disconnected, and port (C) and port (T) are
connected.
5.
Spool (2) moves up and down so that the thrust force of plunger (5) is balanced with the total of the pres-
sure in port (C) and load of spring (3).
6.
The circuit pressure between EPC valve and control valve is controlled in proportion to the signal current.
10 STRUCTURE AND FUNCTION COMPONENT PARTS OF WORK EQUIPMENT SYSTEM
PC500LC-10R 10-213