Komatsu PC88MR-10 Shop Manual page 162

10 Structure and function
Control valve
LS pressure (PLS1) acts on the left side of unload spool (1).
Since the open area of the left travel valve spool is large, the differential pressure between LS pressure
(PLS1) and pump discharged pressure (PP1) is small.
The differential pressure between pump discharged pressure (PP1) and LS pressure (PLS1) does not
reach the load at installed height of spring (2) (2.45 MPa {25.0 kg/cm
Spring (2) pushes spool (1) to the right.
Pump circuit (PP1) is disconnected from tank circuit (T) and all of pump discharged volume (Q) on the
(PP1) side flows into the left travel circuit.
Since the right travel valve is in HOLD, no LS pressure (PLS2) is generated in it.
Only pump discharged pressure (PP2) is acting.
Pump discharged pressure (PP2) reaches the load at installed height of the spring (2.45 MPa {25.0 kg/
cm 2 }). The spool moves to the left.
All of pump discharged volume (Q) on the (PP2) side is drained into tank circuit (T).
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PC88MR-10