Komatsu Galeo PC138US-8 Shop Manual page 156

SEN02549-02
3. During fine control of both travel valves
Function
When the difference between pump discharge
q
pressure (P1) and (P2) and LS pressure (LS1)
and (LS2) reaches the load of spring (2),
unload spool (1) opens, so excessive oil (maxi-
mum pump delivery - demand flow) flows into
the tank circuit.
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.)
22
10 Structure, function and maintenance standard
Operation
When fine control is carried out on both travel
q
valves, LS pressures (LS1) and (LS2) are gen-
erated and act on the face (SB) of spool (1)
[(P1), (P2), (LS1), and (LS2) are separated].
When the difference between pump discharge
q
pressure (P1) and (P2) and LS pressure (LS1)
and (LS2) reaches the load of spring (2), spool
(1) moves to the left, and pump discharge
pressures (P1) and (P2) are connected to tank
circuit (T) and the excessive oil (maximum
pump delivery - demand flow) flows.
In other words, the excessive oil (maximum
q
pump delivery - demand flow) above the
strokes of both travel valves flows into tank cir-
cuit (T).
PC138US, USLC-8