Komatsu PC88MR-10 Shop Manual page 184

10 Structure and function
Control valve
When boom LOWER operation is performed
When the boom LOWER operation is performed, pilot spool (3) is pushed by pilot pressure (P1) from the
PPC valve and the pressurized oil in chamber (b) in the poppet is drained.
The pressure in port (Ab) is increased by the pressurized oil from the bottom side of boom cylinder, but the
oil pressure in chamber (b) is decreased by orifices (a1) and (a2).
When the pressure in chamber (b) decreases below that in port (Ab), poppet (2) opens and the
pressurized oil from port (Ab) flows into port (Aa) and then flows into the control valve.
10-106 PC88MR-10