Komatsu PC20R-8 Shop Manual page 75

2) During fine control of the control valve, when the demand flow for the actuator is within the amount discharged by
the minimum swash plate angle of the pump, pump discharge pressure P
2
kg/cm ).
When the difference in pressure between pump discharge pressure P
spring (2) (16 bar (16 kg/cm
2
cm ).
S
1
OPERATION
During fine control of control valve
. When fine control is carried out on the control
valve, LS pressure P
area S3 at the right and of spool (1).
When this happens, the area of the opening of the
control valve spool is small, so there is a big differ-
ence between LS pressure P
charge pressure P .
P
. When the difference in pressure between pump
discharge pressure P
reaches the load of spring (2), spool (1) moves to
the right, and pump circuit P
are connected.
PC20R-8 PC27R-8
2
)) the unload valve opens, so LS differential pressure DP
1 P
A T
is generated and acts on
LS
and pump dis-
LS
and LS pressure P
P
and tank circuit T
P
P
P
2
. In other words, pump discharge pressure P
to a pressure equal to the force of spring (2) (16 bar
(16 kg/cm
pressure DP
LS
is set to LS pressure P
P
and LS pressure P reaches the load of
P LS
becomes 16 bar (16 kg/
LS
B
LS
T
2
))+LS pressure P , and LS differential
LS
becomes 16 bar (16 kg/cm
LS
+16 bar (16
LS
S S
3 2
RKP00730
is set
P
2
).
10-57