Group 4 Single Operation - Hyundai R480LC-9S Service Manual

GROUP 4 SINGLE OPERATION

GROUP 4 SINGLE OPERATION
1. BOOM UP OPERATION 1. BOOM UP OPERATION
When the RH control lever is pulled back, the boom spools in the main control valve are moved to
the up position by the pilot oil pressure from the remote control valve.
The oil from the A1 and A2 pump flows into the main control valve and then goes to the large
chamber of boom cylinders.
At the same time, the oil from the small chamber of boom cylinders returns to the hydraulic oil tank
through the boom spool in the main control valve. When this happens, the boom goes up.
The excessive pressure in the boom cylinder bottom end circuit is prevented by relief valve.
When the boom is up and the control lever is returned to neutral position, the circuit for the holding
pressure at the bottom end of the boom cylinder is closed by the boom holding valve.
This prevents the hydraulic drift of boom cylinder.
ps1
PS
pa11
DR1
pc1
B5
A5
pb9
pb5
ARM1
pci
pa9
pa5
PO
B4
A4
pb4
OPTION
pa4
A3
B3
pb3
pb3
BOOM2
pb7
pa3
B2
A2
pb2
SWING
DR3
pa2
pc6
B1
A1
pb1
TRAVEL-RH
pa1
pr1
P1 PT PP
PS
SH
3-13
ps2
PS
T3 T1 T2 T4
ARM2
BUCKET
Boom holding valve
Relief valve
BOOM1
TRAVEL-LH
STRAIGHT
TRAVEL
PH
PA
P2
PS
A1 A2
pa10
B9
A9
pb9
pa9
B8
A8
pa11
pb8
pa8
DR2
pc2
A7
B7
pc2
pb3
pb7
pa3
pa7
B6
A6
pb6
pa6
P3
4809S3HC10