GROUP 3 PILOT CIRCUIT

Remote control valve Remote control valve

RCV pedal (RH lever)
(LH lever)

Safety lock
solenoid valve Swing parking brake

Control valve
Travel speed solenoid valve

Max flow cut off solenoid valve

Power boost solenoid valve

Swing priority solenoid valve

Line filter
Main pump
Relief valve
35kgf/cm2

Pilot pump
Suction filter

3-05 (140-7 TIER)

The pilot circuit consists of suction circuit, delivery circuit and return circuit.
The pilot pump is provided with relief valve, receives the oil from the hydraulic tank through the
suction filter.
The discharged oil from the pilot pump flows to the remote control valve through line filter, EPPR
valve, solenoid valve assemblies, swing parking brake, main control valve and safety lock solenoid
valve.

3-5
1. SUCTION, DELIVERY AND RETURN CIRCUIT

ARM BUCKET BOOM

CYLINDER CYLINDER CYLINDER

TRAVEL MOTOR

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5

C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

C4
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
ARM 1
SWING MOTOR Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3) PILOT
Pb1 Pa1 Pc1 Pd1 PUMP

SW AM BK BM

Pb4 Pk Pm1 Pm2 Pz

A5 A4 A3 A2 A1
PG
(1) (3) (2) (4) (3) (1) (2) (4) P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
sh P2
B A D E G F H J T P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER

1607A3HC02

The pilot pump receive oil from the hydraulic tank. The discharged oil from the pilot pump flows to
the safety solenoid valve through the line filter. The oil is filtered by the line filter. The pilot relief valve
is provided in the pilot pump for limiting the pilot circuit pressure.
The oil filtered by line filter flows remote control valve through safety solenoid valve.
The return oil flow into the hydraulic tank.

3-6
2. SAFETY VALVE(SAFETY LEVER)

ARM BUCKET BOOM

CYLINDER CYLINDER CYLINDER

TRAVEL MOTOR

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5

C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

C4
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
ARM 1
SWING MOTOR Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3) PILOT
Pb1 Pa1 Pc1 Pd1 PUMP

SW AM BK BM
SAFETY
SOLENOID
Pb4 Pk Pz VALVE
Pm1 Pm2
LEVER UP
A5 A4 A3 A2 A1
PG
(1) (3) (2) (4) (3) (1) (2) (4) P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
sh P2
B A D E G F H J T P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER
LEVER DOWN

1607A3HC03

When the lever of the safety solenoid valve is moved upward, oil flows into the remote control valve
through solenoid valve and line filter.
When the lever of the safety solenoid valve is moved upward, oil does not flow into the remote control
valve, because of the blocked port.

3-7
3. ARM REGENERATION SYSTEM

ARM BUCKET BOOM

CYLINDER CYLINDER CYLINDER

TRAVEL MOTOR

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5

C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

C4
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
ARM 1
SWING MOTOR Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3) PILOT
Pb1 Pa1 Pc1 Pd1 PUMP

SW AM BK BM

Pb4 Pk Pm1 Pm2 Pz

A5 A4 A3 A2 A1
PG
(1) (3) (2) (4) (3) (1) (2) (4) P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
SH
P2
B A D E G F H J T P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER

1607A3HC04

Then the heavy duty mode switch on the cluster is pushed ON, the arm regeneration solenoid valve
is deactivated and the arm regeneration spool is returned to neutral position.
Then, the arm regeneration function is activated and arm operation speed is increased.

3-8
4. TRAVEL SPEED CONTROL SYSTEM
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER

CONTROL PISTON
PILOT VALVE
TRAVEL MOTOR
L/H RED RED R/H

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5
B A B A
C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

Pk
C4
Dr
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
SWING MOTOR ARM 1
Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3) PILOT
Pb1 Pa1 Pc1 Pd1 PUMP

SW AM BK BM

Pb4 Pk Pm1 Pm2 Pz

A5 A4 A3 A2 A1

P4 PG
(1) (3) (2) (4) (3) (1) (2) (4) (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
sh P2
B A D E G F H J T
P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER
1607A3HC05

When the travel speed switch is pushed, the travel speed solenoid valve is actuated and the
discharged oil from the pilot pump flows to the Pk port of pilot valve in the travel motors.
As a result, the control piston is pushed by the main oil flow, thus the displacement is minimized.
When the travel speed switch is pushed once more, the travel speed solenoid valve is return to
original position by the force of spring, the hydraulic oil of Pk port returns to the hydraulic tank.
As a result, the control piston is returned by the main oil flow, thus the displacement is maximized.

3-9
5. MAIN RELIEF PRESSURE CHANGE SYSTEM
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER

TRAVEL MOTOR

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5

C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

C4
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
ARM 1
SWING MOTOR Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3) PILOT
Pb1 Pa1 Pc1 Pd1 PUMP

SW AM BK BM

Pb4 Pk Pz
Pm1 Pm2
A5 A4 A3 A2 A1
PG
(1) (3) (2) (4) (3) (1) (2) (4) P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
sh P2
B A D E G F H J T P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER

1607A3HC06

When the power boost switch on the left control lever is pushed ON, the power boost solenoid valve
is actuated, the discharged oil from the pilot pump flows into Pz port of the main relief valve of main
control valve; then the setting pressure of the main relief valve is raised from 330kgf/cm2 to 360kgf/cm2
for increasing the digging power. And even when pressed continuously, it is canceled after 8
seconds.

3-10
 6. MAX FLOW CUT OFF SYSTEM

ARM BUCKET BOOM

CYLINDER CYLINDER CYLINDER

TRAVEL MOTOR

Pn2 Pn1

C6
D6
Pc6
Pd6

OPTION

B5

C5 A5
D5 Pb5
Pc5
Pd5 Pa5
OPTION BUCKET

C4
D4 DR3 B4
Pc41 Pb4
Pc40
Pa4
Pd40
ARM 1
SWING MOTOR Pc42
ARM
V3 REGENERATION
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2

B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1
TRAVEL
C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
(2) (1) (4) (3) T1
Pb1 Pa1 Pc1 Pd1
Pz
SW AM BK BM

a1 P1 P2 a2

Dr#, T
(1) (3) (2) (4) (3) (1) (2) (4)
sh

B A D E G F H J MCV "Pn2" MCV "Pn1"

Pm1 Pm2
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20

Pb4 Pk Pm1 Pm2 Pz

A5 A4 A3 A2 A1
M
Dr a3
PG
P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
P2
T P1

LINE FILTER

1607A3HC07

When the breaker operation mode is selected on the cluster, max flow cut off solenoid valve actuates
automatically.
Thus pilot pressure(Pm1,2) is sent to the regulator and pump discharge volume is decreased.

3-11
7. SWING PARKING BRAKE RELEASE
ARM BUCKET BOOM
CYLINDER CYLINDER CYLINDER
TRAVEL MOTOR

Pn2 Rs Pn1

C6
D6
Pc6

Pd6
OPTION

B5
SWING MOTOR
C5 A5
D5 Pb5
SH Pc5
Pd5 Pa5
OPTION BUCKET
PG
C4
D4 B4
DR3
Pc41 Pb4
Pc40
Pa4
Pd40
Mu ARM 1
Pc42
ARM
V3 REGEN
Pc3 Pb3
Pa21 DR2
Pd41
BOOM 2 ARM 2
A(cw) B(ccw) B2
C2
Pb21 A2
D2
DR1
Pc2 Pb20
Pd2 Pa20
SWING BOOM 1

C1 B1
D1 Pc1 Pb1 A1
Pd1 Pa1

TRAVEL(LH) TRAVEL(RH)

P0
TRAVEL T1

P2 P1 Pz

FRONT REAR
Dr#, T PUMP PUMP
(2) (1) (4) (3)
Pb1 Pa1 Pc1 Pd1 PILOT
PUMP

SW AM BK BM

Pb4 Pk Pm1 Pm2 Pz

A5 A4 A3 A2 A1
PG
(1) (3) (2) (4) (3) (1) (2) (4) P4 (S/Motor)
P3 P0(MCV) HYDRAULIC TANK
SH
P2
B A D E G F H J T P1
Pc2 Pd2 Pd40 Pc40 Pa5 Pb5 Pa20 Pb20 LINE FILTER

1607A3HC08

When the swing control lever is tilted, the pilot oil flow into SH port of shuttle valve, this pressure
move spool so, discharged oil from pilot valve flow into PG port.
This pressure is applied to swing motor disc, thus the brake is released.
When the swing control lever is set in the neutral position, oil in the swing motor disc cylinder is
drained, thus the brake is applied.

3-12