22.10
COMBINED CIRCUIT
This section describes only the difference in combined
operation.
(1) Boom up / travel, pilot circuit
(2) Boom up / travel, main circit
22.10.1 BOOM UP / TRAVEL, PILOT
CIRCUIT
(1) Operation:
<Operation: Different point of pilot circuit from
independent operation >
1.
The mechatro controller outputs command current
to travel straight solenoid proportional valve after
signal processing, and the solenoid valve outputs
secondary pressure and acts on PTb port of C/V
(2).
2.
Then the pressure of PTb port switches the travel
straight valve.
22.10.2 BOOM UP / TRAVEL, MAIN
CIRCUIT
(1) Purpose:
To insure straight travel movement during travel
operation even if the attachment is operated.
(2) Principle:
The travel action and the attachment action are
actuated by separate pumps.
(3) Operation:
1.
P1 pump delivery oil flows through P1 port of
C/V(2) and branches off in P1 parallel circuit and
travel straight spool.
P2 pump delivery oil flows through P2 port of
C/V(2) and branches off in P2 tandem circuit
and travel straight spool.
2.
The delivery oil flowed into P1 parallel circuit of
P1 pump opens check valve CP1 and LCb and
flows in boom spool, which exerts on boom up
operation.
The delivery oil flowed into travel straight spool of
P1 pump opens check valve CT2 because the
travel straight spool is shifted, and flows in boom
conflux spool and exerts on boom up operation
with the internal oil conflux.
(In travel straight operation, P1 pump delivery oil
exerts on swing operation of attachment.)
3.
The delivery oil flowed into P2 tandem circuit of
P2 pump flows in left travel spool to travel
leftward.
The delivery oil flowed into travel straight spool of
P2 pump flows in right travel spool because the
travel straight spool is shifted and exerts on the
right travel operation.
(In travel straight operation, P2 pump delivery oil
exerts on travel operation.)
4.
However, a portion of the flow is led to the
travel straight spool notch restriction. The speed
of attachments like travel, boom, etc. is adjusted
by the circuit of restriction.
[
22. HYDRAULIC SYSTEM
]
22-26
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