Komatsu PC20R-8 Shop Manual page 83

7. L.H., R.H. travel junction circuit
FUNCTION
. To compensate for any difference in the oil flow in the left and right travel circuits when travelling in a straight
line, the junction circuit opens when the left and right travel spools are operated.
In this way, the flow of oil to the left and right travel motors is almost the same when travelling in a straight line, so
there is no travel deviation.
. When steering the machine, the difference in the load pressure returns the reducing valve of the travel on the
inside of the turn and the opening of the notch in the travel junction valve spool becomes smaller, so the machine
can be steered.
A
L
1L
3
P
P
OPERATION
When travelling in a straight lint
. When left and right travel spools (1) are operated,
the pump discharge flows from pump circuit P
and circuits P and P
AL
and A .
R
. When travelling in a straight line, to make actuator
circuits P and P
AL AR
valves (2) are pushed to the right by the same
amount, and notch a and the travel junction circuit
are opened.
. In this way, the left and right travel actuator circuits
are interconnected by the travel junction circuits, so
if any difference occurs in the flow of oil to the left
and right travel motors, the compensation is carried
out to prevent any deviation in travel.
PC20R-8 PC27R-8
LEFT TRAVEL
P
AL
a
to actuator circuits A
AR
equal, left and right reducing
A
R
T
1R
P
LS
2 3
c
a
P
L
RIGHT TRAVEL
P
AR
a
RKP00423
T
2
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