Komatsu PC88MR-10 Shop Manual page 227

Operation of solenoid valve
When solenoid valve is "de-energized" (circuit is disconnected)
Coil (1) is de-energized when the signal current does not flow to coil (1).
Spool (2) is pushed back to the left with the reaction force of spring (3).
Between port (P) and port (A) are disconnected and pilot pressure oil does not flow from port (A) to the
actuator. At the same time, port (T) opens and oil from actuator is drained to the hydraulic tank.
When solenoid valve is "energized" (circuit is interconnected)
Coil (1) is energized when the signal current flows to coil (1).
Accordingly, spool (2) is pushed to the right by push pin (4).
The circuit between port (P) and port (A) opens and pilot pressure oil flows from port (A) to the actuator. At
the same time, port (T) closes and oil from actuator does not flow to the hydraulic tank.
PC88MR-10
10 Structure and function
Solenoid valve
10-149