Group 4 Single Operation
Group 4 Single Operation
Group 4 Single Operation
1. BOOM UP OPERATION
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
OPTION BUCKET
Pd5 CK2
P05
C4 P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 BOOM HOLDING VALVE
Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC10
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.
3-15
2. BOOM DOWN OPERATION
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
OPTION BUCKET
Pd5 CK2
P05
C4 P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 BOOM HOLDING VALVE
Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC11
When the RH control lever is pushed forward, the boom spools in the main control valve are moved
to the down position by the pilot oil pressure from the remote control valve.
The oil from the A2 pump flows into the main control valve and then goes to the small chamber of
boom cylinders. At the same time, the oil from the large chamber of boom cylinders returns to the
hydraulic tank through the boom spool in the main control valve.
When the down speed of boom is faster, the oil returned from the large chamber of boom cylinder
combines with the oil from the rear pump, and flows into the small chamber of the boom cylinder.
This prevents cylinder cavitation by the negative pressure when the rear pump flow can not match
the boom down speed. And the excessive pressure in the boom cylinder rod end circuit is prevented
by the relief valve.
3-16
3. ARM IN OPERATION
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
RELIEF
OPTION VALVE BUCKET
Pd5 CK2
P05
C4 ARM HOLDING VALVE P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
MAKE UP VALVE
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC12
When the LH control lever is pulled back, the arm spools in the main control valve are moved to the
roll in 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 arm cylinder.
At the same time, the oil from the small chamber of arm cylinder returns to the hydraulic oil tank
through the arm spool in the main control valve. When this happens, the arm roll in.
When the roll in speed of arm is faster, the oil returned from the small chamber of arm cylinder
combines with the oil from both pump, and flows into the large chamber of the arm cylinder by a
make up valve.
The excessive pressure in the arm cylinder bottom end circuit is prevented by relief valve.
Refer to page 3-12 for the arm regeneration.
3-17
4. ARM OUT OPERATION
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
RELIEF
OPTION VALVE BUCKET
Pd5 CK2
P05
C4 P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
ARM HOLDING VALVE Pc42
MAKE UP VALVE
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC13
When the LH control lever is pushed forward, the arm spools in the main control valve are moved to
the roll out 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 small
chamber of arm cylinder. At the same time, the oil from the large chamber of arm cylinder returns to
the hydraulic oil tank through the arm spool in the main control valve.
When this happens, the arm roll out. When the roll out speed of arm is faster, the oil returned from
the large chamber of arm cylinder combines with the oil from both pump, and flows into the small
chamber of the arm cylinder by a make up valve.
The excessive pressure in the arm cylinder rod end circuit is prevented by relief valve.
When the arm is rolled out and the control lever is returned to neutral position, the circuit for the
holding pressure at the rod end of the arm cylinder is closed by the arm holding valve.
This prevents the hydraulic drift of arm cylinder.
3-18
5. BUCKET IN OPERATION
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
Center bypass valve
RELIEF VALVE
P06 B5
C5 A5
D5
MAKE UP VALVE
Pc5 Pb5 Pcb
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC14
When the RH control lever is manually placed in the bucket roll in position. Then the oil flows from
pilot pump through the pilot valve to bucket section of the main control valve. Here the spool position
is moved to bucket roll in position.
The center bypass valve is change over by the pilot pressure (Pcb) and then the oil from A2 pump is
joint to the flow of A1 pump via check 1 and external piping.
The oil flows from both pump through rod end of the cylinder through the bucket section returned to
the hydraulic tank.
The cavitation which will happen to the bottom of the bucket cylinder is prevented by a make up
valve, on other hand. The excessive pressure is also prevented by an overload relief valve in the
main control valve.
3-19
6. BUCKET OUT OPERATION
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
MAKE UP VALVE
Pcb
Center bypass valve
RELIEF VALVE
P06 B5
C5 A5
D5 Pcb
Pc5 Pb5
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC15
When the RH control lever is manually placed in the bucket roll out position. Then the oil flows from
pilot pump through the pilot valve to bucket section of the main control valve. Here the spool position
is moved to bucket roll out position.
The oil flows from A2 pump through bucket section of main control valve to the rod end of the bucket
cylinder, and to roll out bucket.
The return oil flows from the bottom end of the cylinder through the bucket section returned to the
hydraulic tank.
The cavitation which will happen to the rod of the bucket cylinder is prevented by a make up valve,
on other hand. The excessive pressure is also prevented by an overload relief valve in the main
control valve.
3-20
7. SWING OPERATION
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
OPTION BUCKET
Pd5 CK2
P05
C4 P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC16
When the LH control lever is manually placed in the left (right) swing position. Then the oil flows from
A1 pump through the swing section of the main control valve to swing motor to left (right) swing the
superstructure. The return oil flows from swing motor through the swing section of the main control
valve returned to the tank.
When the control lever placed in the neutral position, the pressure of the pilot oil passage down.
Then the brake release valve returned to the neutral position and the oil is returned from the brake
piston to the tank. And the brake is set to "ON". The swing parking brake, make up valve and the
overload relief valve are provide in the swing motors. The cavitation which will happen to the swing
motor is prevented by the make up valve in the swing motor itself.
3-21
SWING CIRCUIT OPERATION
PARKING BRAKE
SH
BRAKE OFF
PG
BRAKE ON
BYPASS VALVE
Dr
MOTOR BRAKE VALVE
GB GA
MAKE UP VALVE
3-22
8. TRAVEL FORWARD AND RE
REVERSE
VERSE O
OPERATION
PERATION
TRAVEL MOTOR
Pn2 Pn1
CK1 PG PG
RS
Pcb
P06 B5
C5 A5
D5
Pc5 Pb5
Pa5
OPTION BUCKET
Pd5 CK2
P05
C4 P04
D4
B4
DR3
Pc41
Pc40 Pb4
Pd40
SWING MOTOR Pa4
ARM 1 ARM REGENERATION
Pc42
Pb3
Pc3
DR2
Pa21
ARM 2
BOOM 2 Pd41
V3 B2
C2
A2
D2
Pc2 Pb21
Pd2 DR1
Pb20
DR4
SWING Pa20
P02
BOOM 1
P03 Patt
C1 B1
D1 Pb1 A1
Pc1
Pd1 Pa1
TRAVEL(LH)
V4
DR0 TRAVEL(RH)
V1
P01
PS
Ptr
P1 P2 PU T1
A1 A2
HYDRAULIC TANK
FRONT REAR PILOT
PUMP PUMP PUMP
3009SH3HC18
When the right and left travel levers are manually placed to the forward or reverse position, the oil
flows from pilot pump through the pilot valve to travel sections of the main control valve.
Here, spool position is moved to forward and reverse position. The oil flows from A2 pump through
the travel (RH) section of the main control valve and turning joint to the right travel motor and oil flows
from A1 pump through the travel (LH) section of the main control valve and turning joint to the left
travel motor and move the machine forward or reverse.
The return oil flows from both travel motor through the turning joint and travel (RH, LH) sections
returned to the tank.
3-23
TRAVEL CIRCUIT OPERATION
L/H R/H
Dr Dr
OVERLOAD
RELIEF VALVE
Pi Pi
N N
Am Bm Bm Am
A P B
C Dr D
Pk
3009SH3HC19
3-24