Komatsu PC500LC-10R Shop Manual page 270

COMPONENT PARTS OF HYDRAULIC SYSTEM
OPERATION OF BOOM HYDRAULIC DRIFT PREVENTION VALVE OF CONTROL
VALVE
When the boom "RAISE" operation is performed
1.
When the boom is operated to "RAISE", the pressurized oil from the control valve acts leftward to the right
side of the ring area (S) whose outside diameter is diameter (d1) of the poppet (5) and inside diameter is
seat diameter (d2).
2.
The force acting leftward on area (S) pushes and compresses spring (4) and moves poppet (5) to the left.
3.
The oil from the control valve flows through the opening of poppet (5) to the bottom side of the boom cylin-
der.
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10 STRUCTURE AND FUNCTION
PC500LC-10R
AEP21629