FUNCTION
CONTROL VALVE
6
3
CONTROL VALVE 3J0AX00
Switch valve
This valve switches among the circuits of the bucket,
arm, boom, swing, and auxiliary line hydraulics when any
of them is activated during travel operation. The oil sup-
plied by the pump P3 is directed to a section other than
the travel section, which enables straight travel together
with other operations under combined control.
When the switch valve is activated:
When travel operation and other operations are per-
formed at the same time, the pilot pressure is directed to
the port P1, which causes the spool (1) to be pushed up.
This allows the oil that entered the port P to flow through
the parallel passage (2) as well as the spool head and
the second parallel passages A and B. The second par-
allel passage A is connected to the boom and bucket
sections while the second parallel passage B is connect-
ed to the arm and swing sections, allowing combined op-
eration involving travel and other operation.
When the switch valve is not activated:
The spool (1) does not get switched because the pilot
passage is open to the tank passage and thus the pres-
sure in the port Pi is equal to the pressure in the tank. As
a result, the oil that entered the port P flows into the cen-
ter bypass passage (3). In addition, part of the oil flows
through the connected parallel passage (2) and the doz-
er blade and slew sections.