Komatsu Galeo PC138US-8 Shop Manual page 173

10 Structure, function and maintenance standard
Hydraulic drift prevention valve
1. When boom is raised
Function
While the boom lever is not operated, the
q
hydraulic drift prevention valve prevents pres-
surized oil from leaking from the boom bottom
through spool (1) to prevent the boom from
drifting hydraulically.
PC138US, USLC-8
Operation
If the boom is raised out, the main pressure
q
from the control valve pushes up poppet (5).
As a result, the main pressure from the control
valve flows through the valve into the boom
cylinder bottom.
SEN02549-02
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