2-23
Bucket out operation
T1
T2
P1
Boom
Boom lock
valve comp
P1
Dr1
To cylinder rod side
via A10 port
To B10 port via
cylinder head side
P1 side parallel passage
Spool changeover
direction
B10
To bridge passage
in bucket comp.
A10
Bucket
Pa10
R35Z72MCV18
Bucket out operation
When the bucket out operation is carried out, the secondary pressure from the remote control valve
flows into Pa10 port to change over the bucket spool.
Since the P1 side bypass passage is shut off at the bucket section after the bucket spool
changeover, the oil flowed from P1 port flows through the check valve provided above the bypass
passage in the travel section into the P1 side parallel passage.
Also, since a passage between A10 port and the bridge passage is opened after the spool
changeover, the oil flowed into the P1 side parallel passage flows through the load check valve in
the bucket section into A10 port via the bridge passage and then the head side of the bucket
cylinder.
On the other hand, the oil returned from the head side of the bucket cylinder flows into B10 port to
the tank passage that has opened after the spool changeover.