Komatsu Galeo PC138US-8 Shop Manual page 157

10 Structure, function and maintenance standard
4. When both travel valves are operated
Function
During operation of both travel valves, when
q
the demand flow becomes maximum, the oil
flow to tank circuit (T) is cut off, and all pump
delivery (Q) flows to both travel circuits.
Since the pump merge-divider spool 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 .)
PC138US, USLC-8
Operation
When both travel valves are operated to the
q
stroke ends, LS pressures (LS1) and (LS2) are
generated and act on the face (SB) of unload
spool (1) [(P1), (P2), (LS1), and (LS2) are sep-
arated].
The area of the openings of both travel valve
q
spools is large, so LS pressures (LS1) and
(LS2) are not so different from pump discharge
pressures (P1) and (P2).
For this reason, the difference between pump
q
discharge pressure (P1) and (P2) and LS pres-
sure (LS1) and (LS2) 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 (P2) and tank circuit (T) are shut off, and
all pump delivery (Q) flows to the actuator cir-
cuit.
SEN02549-02
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