Hyundai r35z-7 Workshop Manual page 56

6) ARM OPERATION
Arm in operation
When the arm in operation is carried out, the secondary pressure from the remote control valve is
applied to Pb5 port to change over the arm spool. The secondary pressure is also applied to the
pilot chamber (arm in port) on the connecting section spring chamber side that has been connected
through the piping. Therefore, when the operation is carried out together with the boom up
operation at the same time, the connecting spool is hard to change over against the pilot pressure
for arm in operation.
Since the P2 port bypass passage is shut off at the arm section after the arm spool change over,
the oil flowed from P2 port flows through the travel section and a passage between travel section
and arm section into the P2 side parallel passage.
Also, since the oil flowed from P3 port flows through the direction of dozer
section and then into the P2 side parallel passage via the check valve in the P3 supply section, the
connecting flow of P2 pump and P3 pump is supplied to the P2 side parallel passage. [Although the
P3 side bypass passage is also connected to the P1 side parallel passage through the check valve
in the P3 section, there is no oil flow into the P1 side as long as the P1 side sections (boom ,
bucket) are not operated.]
Since a passage between B5 port and the bridge passage is opened after the spool changeover,
the oil flowed into the P2 side parallel passage flows through the load check valve in the arm section
into B5 port via the bridge passage and then into the head side of the arm cylinder.
On the other hand, the oil returned from the rod side of the arm cylinder flows into A5 port to the
tank passage that has opened with the spool's notch after the spool changeover. Then, the arm
cylinder extends to make the arm in.
T1
T2
P3
P3
Arm in
Pb5
To bridge passage
PTO
Arm
Travel
To A5 port via
cylinder rod side
P2
P2
Arm in operation
B5
A5
2-24
boom swing swing
Pb5
Spool changeover
direction
To cylinder head side
via B5 port
R35Z72MCV19