Komatsu Galeo PC138US-8 Shop Manual page 158

SEN02549-02
5. When either travel valve is operated
Function
The demand flow decided by the valve stroke
q
is sent to the travel circuit on the operated
travel valve side and the all pump delivery is
sent to the tank circuit on the non-operated
travel valve side.
Since the pump merge-divider valve is at the
q
separate position, pump discharge pressures
(P1) and (P2) are separated. LS pressures
(LS1) and (LS2) are also separated.
The swash plate angle of the pump becomes
q
maximum, so the pump delivery becomes
maximum. (For details, see the sections on the
pump merge-divider valve.)
Operation
When left travel valve is operated to stroke end
and right one is at HOLD.
When the left travel valve is operated to the
q
stroke end, LS pressure (LS1) is generated
and acts on the face (SB) of unload spool (1).
24
10 Structure, function and maintenance standard
The area of the openings of left travel valve
q
spool is large, so LS pressures (LS1) is not so
different from pump discharge pressures (P1).
For this reason, the difference between pump
q
discharge pressure (P1) and LS pressure
(LS1) does not reach the load of spring (2), so
spool (1) is pushed to the right by spring (2).
As a result, pump discharge pressures (P1)
q
and tank circuit (T) are shut off, and all pump
delivery (QP1) on the (P1) side flows to the left
travel circuit.
Since the right travel valve is at HOLD, LS
q
pressure (LS2) is not generated, so only pump
discharge pressure (P2) acts.
When pump discharge pressure (P2) reaches
q
the load of spring (2), spool (1) moves to the
left, and all pump delivery (QP2) on the (P2)
side flows into tank circuit (T).
PC138US, USLC-8