Komatsu PC20R-8 Shop Manual page 80

4. Pressure compensation valve
FUNCTION
. During compound operations, if the load pressure becomes lower than the other actuator and the oil flow tries to
increase, compensation is received. (When this happens, the other actuator being used for compound operation
(right side) is at a higher load than the actuator on this side (left side)).
Side receiving
compensation
A
P
PA
2
P
P
OPERATION
. If the load pressure of the other actuator (right side)
becomes higher during compound operations, the
oil flow in actuator circuit A on this side (left side)
tries to increase.
. If this happens, the LS pressure P
tuator acts on spring chamber P
valve (1) and flow control valve (2) are pushed to
the left ( ).
. Flow control valve (2) throttles the area of opening
between pump circuit P
P , and pressure loss is generated between P
PA
and P .
PA
10-62
W
a
of the other ac-
LS
, and reducing
LS1
and spool upstream
P
Side providing
compensation
T
P
A
P
LS1
1
P
LS
. Flow control valve (2) and reducing valve (1) are ba-
lanced in position where the difference in pressure
between P
cing valve (1) and the pressure loss between P
and P on both sides of flow control valve (2) are
PA
the same.
. In this way, the pressure difference between up-
stream pressure P
P of both spools used during compound opera-
A
tions is the same, so the pump flow is divided in
proportion to the area of opening of notch a of each
P
spool.
W
a
P
PA
and P acting on both ends of redu-
LS A
and downstream pressure
PA
PC20R-8 PC27R-8
T
P
A
RKP00403
P