Hyundai HX130LCR Manual page 82

(2) ARM OUT OPERATION
During arm out operation, the pilot secondary pressure from RCV is supplied to the port Pd40 of
spring side and shifts arm 1 spool in the left direction.
The bypass passage is shut off by the movement of the arm 1 spool and the hydraulic fluid from
pump A1 flows into arm 1 spool through the P2 parallel passage. Then it enters into the arm
cylinder rod side through the load check, bridge passage, arm holding valve and the port D4.
Also, the pilot secondary pressure from RCV is supplied to the port Pd41 of spring side and shifts
arm 2 spool in the left direction.
The bypass passage is shut off by the movement of the arm 2 spool and some of the hydraulic
fluid from pump A2 bypassed through bypass notch. The rest of hydraulic fluid from pump A2
flows into the arm summation passage through P1 parallel passage, the check valve, arm 2 spool
and boom 2 spool.
Then it enters into the arm cylinder rod side with the fluid from the arm 1 spool.
The return flow from the arm cylinder head side returns to the hydraulic tank through the port C4,
the arm 1 spool and tank passage.
Load check
P2 Parallel passage
Tank passage
Arm summation passage
P1 Bypass passage
P1 Bypass passage
C4 D4
Bypass notch
Boom 2 spool
P1 Parallel passage
Check
P1 Parallel passage
Check
2-38
Arm summation passage
Arm 1 spool
Arm out
pilot pressure
From RCV
Arm holding valve
P2 Bypass passage
Arm 2 spool
From RCV
Pd41
Arm roll out
pilot pressure
Pd40
125LCR2MC23