2-34
COMBINED CONTROL OPERATION
Θ
(
(
12)
Both t bucket
When the both travels operation is carried out together with the bucket operation at the same time,
the oil flowed from Pp1 port flows through the orifice passage and into the travel independent signal
passage; both travels and the bucket spool changeover make a passage to the drain port shut off.
Then, the travel independent passage becomes the same pressure as Pp1 port pressure (pilot
primary pressure).
When the travel independent passage becomes Pp1 pressure, the Pp1 pressure is applied to the
connecting spool to change over the connecting spool.
Since the bypass passage from P3 to P2 side, which is a passage to the tank, in restricted, the oil
from P3 side flows into the P1 side parallel passage that is connected through a check valve.
With his circuit arrangement, the bucket section is supplied with pressure oil from P3 during both
travels operation, the simultaneous operation becomes possible.
Besides, since each of P1 and P2 is used independently during both travels and only P3 is used for
bucket operation, stable travel is possible to continue even if there is change in the bucket load.
Travel independence operation
To travel motor
Oil flows from P1 side parallel passage, through the bridge passage
in the bucket comp., and in to the cylinder rod side via A10 port.
To P1 side parallel passage
P3
T1
T2
P2
P1
Dr1
P1
P2
To travel motor
P3
To P1 side parallel passage
Pp1
Bucket
Boom lock
valve comp.
R35Z72MCV28
