GROUP 4 SINGLE OPERATION

1. BOOM UP OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21 BOOM
BOOM 2 ARM 2 HOLDING
C2 RELIEF VALVE B2
P ACC1 BRAKE VALVE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC10

When the right 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 head side 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 head side of the boom cylinder is closed by the boom holding valve.
This prevents the hydraulic drift of boom cylinder.

3-14
 2. BOOM DOWN OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2 RELIEF
C2 VALVE B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC11

When the right control lever is pushed forward, the boom 1 spool in the main control valve is 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 1 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 A2 pump, and flows into the small chamber of the cylinder.
This prevents cylinder cavitation by the negative pressure when the A2 pump flow can not match the
boom down speed. And the excessive pressure in the boom cylinder rod side is prevented by the
relief valve.

3-15
 3. ARM IN OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5 MAKE UP
DR5 VALVE
C4 P05 P04
RELIEF
VALVE
D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC12

When the left control lever is pulled back, the arm spools in the main control valve are moved to the
arm 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 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 rolls in.
The excessive pressure in the arm cylinder head side is prevented by relief valve.
The cavitation which will happen to the head side of the arm cylinder is also prevented by the make-
up valve in the main control valve.

3-16
 4. ARM OUT OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5 RELIEF
DR5 VALVE
C4 P05 P04
MAKE UP
VALVE
D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
ARM V3 ARM
HOLDING REGEN Pb3
VALVE Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC13

When the left control lever is pushed forward, the arm spools in the main control valve are moved to
the arm 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
rolls out. The cavitation which will happen to the rod side of the arm cylinder is also prevented by the
make-up valve in the main control valve. When the arm is roll out and the control lever is returned to
neutral position, the circuit for the holding pressure at the rod side of the arm cylinder is closed by
the arm holding valve. This prevent the hydraulic drift of arm cylinder.

3-17
 5. BUCKET IN OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

RELIEF
VALVE
TURNING DOZER MAKE UP
JOINT PS VALVE
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC14

When the right control lever is pulled left, the bucket spool in the main control valve is moved to the
roll in 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 large chamber of
bucket cylinder.
At the same time, the oil from the small chamber of bucket cylinder returns to the hydraulic oil tank
through the bucket spool in the main control valve. When this happens, the bucket rolls in.
The excessive pressure in the bucket cylinder head side is prevented by relief valve.
The cavitation which will happen to the head side of the bucket cylinder is also prevented by the
make-up valve in the main control valve.

3-18
 6. BUCKET OUT OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6
MAKE UP
VALVE RELIEF
DOZER VALVE
TURNING
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

A1 A2
PUMP PUMP
PILOT
PUMP

HYDRAULIC TANK

140W9S3HC15

When the right control lever is pushed right, the bucket spool in the main control valve is moved to
the bucket out 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
bucket cylinder.
At the same time, the oil from the large chamber of bucket cylinder returns to the hydraulic oil tank
through the bucket spool in the main control valve. When this happens, the bucket rolls out.
The cavitation which will happen to the rod side of the bucket cylinder is also prevented by the
make-up valve in the main control valve.

3-19
 7. DOZER/OUTRIGGER UP OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

A1 A2
PUMP PUMP
PILOT
PUMP

HYDRAULIC TANK
140W9S3HC16

When the dozer control lever is pulled back, the dozer spool in the main control valve is moved to
the dozer up position by the pilot oil pressure from the remote control valve.
The oil from the A1 pump flows into the main control valve and then goes to the small chamber of
rear actuator cylinder (dozer or outrigger).
The other case, the oil flows into the small chamber of front actuator cylinder (dozer or outrigger).
At the same time, the oil from the large chamber of dozer (outrigger) cylinders returns to the
hydraulic oil tank through the dozer spool in the main control valve. When this happens, the dozer
(outrigger) goes up.

3-20
 8. DOZER/OUTRIGGER DOWN OPERATION

DOZER/ OUTRIGGER CYLINDER ARM BUCKET

CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2 Pd41
Pa21
BOOM 2 ARM 2
C2 B2
P ACC1 BRAKE VALVE
T2 ACC2 D2 Pc2
ACC1GP Pb21 A2
Pd2
BR1
BR2 SWING DR1
AC1 DR4
Pb20
M2
Pa20
PS

P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3 dr2 SH
P1
PGP P T4(TGP) dr3 (S/Motor)
PS T1
Ai P3
P2 P1 Pu

HYDRAULIC TANK A1 A2
PUMP PUMP
PILOT
PUMP

140W9S3HC17

When the dozer control lever is pushed forward, the dozer spool in the main control valve is moved
to the dozer down position by the pilot oil pressure from the remote control valve.
The oil from the A1 pump flows into the main control valve and then goes to the large chamber of
rear actuator cylinder (dozer or outrigger).
The other case, the oil flows into the large chamber of front actuator cylinder (dozer or outrigger).
At the same time, the oil from the small chamber of dozer (outrigger) cylinders returns to the
hydraulic oil tank through the dozer spool in the main control valve. When this happens, the dozer
(outrigger) goes down.

3-21
 9. SWING OPERATION
DOZER/ OUTRIGGER CYLINDER ARM BUCKET
CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR
OPT-B BUCKET
Pd5
SH DR5
C4 P05 P04
PG
D4 DR3 B4
Dr Pc41
Pb4
Pa4
Pd40
GA GB ARM 1
Pc40 Pc42
Mu
V3 ARM
REGEN Pb3
Pc3
DR2
Pa21
A(CW) B(CCW) ARM 2 Pd41
BOOM 2
C2 B2
P D2
T2 Pc2
Pd2 Pb21 A2
ACC1 BRAKE VALVE DR1
AC1 ACC1GP ACC2 SWING Pb20
DR4
M2 BR1 Pa20
PS

BR2 P02
M BOOM 1
M1 P03 Patt
PS
P K C1 B1
P A1
TP
B D1 Pc1 Pb1
T
Pd1 Pa1
TRAVEL OPT-C
T P0 DR0
T3
P1

PS T1
dr2 Ai
PGP P dr3 P3
T4(TGP)
P2 P1 Pu

RCV LEVER(LH) RCV LEVER(RH)

DR#, dr#
A2 PILOT
SWING ARM BUCKET BOOM
A1 PUMP
P T P T PUMP
PUMP

PO3 Pb4 Pu
(MCV) (MCV) (MCV)

(1) (3) (2) (4) (3) (1) (2) (4)

P4 PG(S/M)
a b d e f g h j P3 PO(MCV)
c P2
Pd2 Pc2 Pd40 Pc40 Pa5 Pb5 PS Pb20 HYDRAULIC TANK
Pc3 T(dr1) P1
Pa20
PS LINE FILTER
140W9S3HC18

When the left control lever is pushed left or right, the swing spool in the main control valve is moved
to the left or right swing position by the pilot oil pressure from the remote control valve.
Also the swing operation preference function is operated by the pilot pressure Pc3 (refer to page
2-34).
The oil from the A1 pump flows into the main control valve and then goes to the swing motor.
At the same time, the return oil from the swing motor returns to the hydraulic oil tank through the
swing spool in the main control valve.
When this happens, the upper structure swings to the left or right.
The swing parking brake, make up valve and the motor brake valve are provided in the swing motor.
The cavitation which will happen to the swing motor is also prevented by the make up valve in the
swing motor itself.

3-22
SWING CIRCUIT OPERATION

SWING MOTOR DEVICE

PARKING BRAKE

SH BRAKE OFF
BRAKE RELEASE VALVE
PG

BRAKE ON
Au
Dr

ANTI-INVERSION VALVE
MOTOR BRAKE VALVE
MAKE UP VALVE

GA GB

B(cw) A(ccw)
MAKE UP
PORT(Mu)

TO / FROM MAIN CONTROL VALVE

14W93HC18A

1) MOTOR BRAKE VALVE

Motor brake valve for the swing motor limits to cushion the starting and stopping pressure of swing
operation and controls the swing motor operating pressure.
2) MAKE UP VALVE
The make up valves prevent cavitation by supplying return oil to the vacuum side of the motor.
3) PARKING BRAKE
This is function as a parking brake only when all of the RCV lever (except dozer lever and travel
pedal) are not operated.
PARKING BRAKE "OFF" OPERATION
The parking brake is released by the pilot pressure oil from the pilot pump.
When the RCV lever placed in the operating position, the pilot oil flows into SH port through the
MCV. This pressure transferred to the brake release valve and the brake release valve is change
over. Then the pilot oil pressure PG lift the brake piston and release the parking brake.
PARKING BRAKE "ON" OPERATION
When all of the RCV 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".
4) ANTI-INVERSION VALVE
This anti-inversion valve absorbs shocks produced as swing motion stops and reduced oscillation
cause by swing motion.

3-23
 10. TRAVEL FORWARD AND RE
REVERSE
VERSE O
OPERATION
PERATION
DOZER/ OUTRIGGER CYLINDER ARM BUCKET
CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2
Pa21
BOOM 2 ARM 2 Pd41
C2 B2
P T2 D2 Pc2
TRAVEL CONTROL Pd2 Pb21 A2
VALVE ACC1 BRAKE VALVE DR1
TRAVEL PILOT ACC1GP ACC2 SWING MAKE UP Pb20
DR4
AC1 SOLENOID BR1 VALVE Pa20
BR2 P02
M2 BOOM 1
PS

M P03 Patt
PS
M1 C1 B1
P K A1
P D1 Pc1 Pb1
B
TP T Pd1 Pa1
TRAVEL OPT-C
P0 DR0
T SH
T3 (S/Motor)
P1
PS T1
dr2 Ai
PGP P dr3 P3
T4(TGP)
P2 P1 Pu

ACCELERATOR
PEDAL RCV LEVER(LH) RCV LEVER(RH)

P T SWING P T ARM BUCKET P T BOOM

DOZER LEVER A1 A2 MAIN PUMP
P T PS PS

1 2 Pi1
(1) (3) (2) (4) (3) (1) (2) (4) (Pn2
Pc1(FW) Pd1(BW) MCV)
Pi2
a b d e f g h j Pc6 Pd6 (Pn1
MCV)
c
Pd2 Pc2 Pd40 Pb5 PS
Pc40 Pa5 PS Pb20 DR#, dr#
Pc3
Pa20
PS P1
ENG
PO3 Pb4 Pu
(MCV) (MCV) (MCV)
B1
T2,T3,T4 P1
HYD P2
P4 PG(S/M) TANK
P3 PO(MCV)

P2
T(dr1) S2 S1 B3 A3
P1
LINE FILTER

140W9S3HC19

When the RH multifunction switch is placed in forward or reverse position, the travel spool in the
main control valve is moved to the forward or reverse position by the pilot oil pressure from pilot
pump through the travel pilot solenoid of travel control valve. The oil from the A1 pump flows into the
main control valve and then goes to the travel motor. At the same time, the oil returned from the
travel motor returns to the hydraulic oil tank through the turning joint and travel spool in the main
control valve.
When this happens, the machine moves forward or reverse.
The cavitation which will happen to the travel motor is prevented by the make-up valve in the main
control valve.

3-24
TRAVEL CIRCUIT OPERATION

TRANSMISSION
T
X2 U
T G

X1
M2 M3
MA MB

OVERLOAD RELIEF VALVE

Gext.
COUNTER BALANCE VALVE
A(fw) S B(bw)

TURNING
JOINT

TO/FROM MAIN CONTROL VALVE

14W93HC19A

Valves are provided on travel motor to offer the following functions.

1) COUNTER BALANCE VALVE

When stopping the motor on a slope descending, this valve prevents the motor from over running.
2) OVERLOAD RELIEF VALVE
Relief valve limits the circuit pressure below 380 kgf/cm2 to prevent high pressure from being
generated at the time of stopping the machine. When stopping the motor, this valve sucks the oil
from lower pressure passage for preventing the negative pressure and the cavitation of the motor.

3-25
 11. A1 AND A2 AXLE BRAKE SYSTEM (SERVICE BRAKE)
DOZER/ OUTRIGGER CYLINDER ARM BUCKET
CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2
Pa21
BOOM 2 ARM 2 Pd41
C2 B2
P BRAKE SUPPLY VALVE
T2 D2 Pc2
Pd2 Pb21 A2
ACC1 BRAKE VALVE DR1
ACC1GP ACC2 SWING Pb20
DR4
AC1 BR1 Pa20
BR2 P02
M2 BOOM 1
PS

M P03 Patt
PS
M1 C1 B1
P K A1
P D1 Pc1 Pb1
B
TP T Pd1 Pa1
TRAVEL OPT-C
P0 DR0
T SH
T3 (S/Motor)
P1
PS T1
dr2 Ai
PGP P dr3 P3
T4(TGP)
P2 P1 Pu

ACCELERATOR
PEDAL RCV LEVER(LH) RCV LEVER(RH)

P T SWING P T ARM BUCKET P T BOOM

DOZER LEVER A1 A2 MAIN PUMP
P T PS PS

1 2 Pi1
(1) (3) (2) (4) (3) (1) (2) (4) (Pn2
Pc1(FW) Pd1(BW) MCV)
Pi2
a b d e f g h j Pc6 Pd6 (Pn1
MCV)
c
Pd2 Pc2 Pd40 Pb5 PS
Pc40 Pa5 PS Pb20 DR#, dr#
Pc3
Pa20
PS P1
ENG
PO3 Pb4 Pu
(MCV) (MCV) (MCV)
B1
T2,T3,T4 P1
HYD P2
P4 PG(S/M) TANK
P3 PO(MCV)

P2
T(dr1) S2 S1 B3 A3
P1
LINE FILTER

POWER TRAIN PUMP

140W9S3HC20

When the brake pedal (valve) is pushed, the discharged oil from the power train pump (P2) flows
into the front and rear axle brake disc through the solenoid valve of brake supply valve.
This pressure is applied to axle brake disc, thus the brake is applied.

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 12. STEERING CIRCUIT OPERATION
DOZER/ OUTRIGGER CYLINDER ARM BUCKET
CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER
Steering cylinder TRAVEL MOTOR

TRANSMISSION

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
STEERING VALVE Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

SPOOL D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2
GEROTOR Pa21
BOOM 2 ARM 2 Pd41
C2 B2
P D2
T2 Pc2
Pd2 Pb21 A2
ACC1 BRAKE VALVE DR1
ACC1GP ACC2 SWING Pb20
DR4
AC1 BR1 Pa20
BR2 P02
M2 BOOM 1
PS

M P03 Patt
PS
M1 C1 B1
P K A1
P D1 Pc1 Pb1
B
TP T Pd1 Pa1
TRAVEL OPT-C
P0 DR0
T SH
T3 (S/Motor)
P1
PS T1
dr2 Ai
PGP P dr3 P3
T4(TGP)
P2 P1 Pu

ACCELERATOR
PEDAL RCV LEVER(LH) RCV LEVER(RH)

P T SWING P T ARM BUCKET P T BOOM

DOZER LEVER A1 A2 MAIN PUMP
P T PS PS

1 2 Pi1
(1) (3) (2) (4) (3) (1) (2) (4) (Pn2
Pc1(FW) Pd1(BW) MCV)
Pi2
a b d e f g h j Pc6 Pd6 (Pn1
MCV)
c
Pd2 Pc2 Pd40 Pb5 PS
Pc40 Pa5 PS Pb20 DR#, dr#
Pc3
Pa20
PS P1
ENG
PO3 Pb4 Pu
(MCV) (MCV) (MCV)
B1
T2,T3,T4 P1
HYD P2
P4 PG(S/M) TANK
P3 PO(MCV)

P2
T(dr1) S2 S1 B3 A3
P1
LINE FILTER

POWER TRAIN PUMP

140W9S3HC21

When the steering wheel is turned to the left or right, the spool within the steering valve turns left or
right hand direction : Because the spool is connected with steering column.
At this time, the oil discharged from the power train pump (P1) flows into steering cylinder through
spool and gerotor within the steering valve.
Then the steering direction is applied.

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 13. RAM LOCK CIRCUIT OPERATION
DOZER/ OUTRIGGER CYLINDER ARM BUCKET
CYLINDER CYLINDER BOOM CYLINDER
OSCILLATING
FRONT AXLE REAR AXLE CYLINDER

TRAVEL MOTOR
CHECK
TRANSMISSION VALVE
LOCKING
VALVE
M

T
P2 P1
P Pi1(Pump) Pi2(Pump)
Rs Pn2 Pn1

C6
D6 Pc6

TURNING DOZER
JOINT PS
Pd6 B5
Puo
C5 A5
D5 Pb5
Pc5
Pa5
SWING MOTOR OPT-B BUCKET
Pd5
DR5
C4 P05 P04

D4 DR3 B4
Pc41
Pb4
Pa4
Pd40
Pc40 ARM 1 Pc42
V3 ARM
REGEN Pb3
Pc3
DR2
Pa21
BOOM 2 ARM 2 Pd41
C2 B2
P D2
T2 Pc2
Pd2 Pb21 A2
ACC1 BRAKE VALVE DR1
ACC1GP ACC2 SWING Pb20
DR4
AC1 BR1 Pa20
BR2 P02
M2 BOOM 1
PS

M P03 Patt
PS
M1 C1 B1
P K A1
P D1 Pc1 Pb1
B
TP T Pd1 Pa1
TRAVEL OPT-C
P0 DR0
T SH
T3 (S/Motor)
P1
PS T1
dr2 Ai
RAM LOCK PGP P dr3 P3
T4(TGP)
SOLENOID P2 P1 Pu

ACCELERATOR
PEDAL RCV LEVER(LH) RCV LEVER(RH)

P T SWING P T ARM BUCKET P T BOOM

DOZER LEVER A1 A2 MAIN PUMP
P T PS PS

1 2 Pi1
(1) (3) (2) (4) (3) (1) (2) (4) (Pn2
Pc1(FW) Pd1(BW) MCV)
Pi2
a b d e f g h j Pc6 Pd6 (Pn1
MCV)
c
Pd2 Pc2 Pd40 Pb5 PS
Pc40 Pa5 PS Pb20 DR#, dr#
Pc3
Pa20
PS P1
ENG
PO3 Pb4 Pu
(MCV) (MCV) (MCV)
B1
T2,T3,T4 P1
HYD P2
P4 PG(S/M) TANK
P3 PO(MCV)

P2
T(dr1) S2 S1 B3 A3
P1
LINE FILTER

140W9S3HC22

When the ram lock switch is selected on the switch panel 2, the ram lock solenoid is changed over.
Thus, the oil discharged from the pilot pump flows into oscillating cylinder through ram lock solenoid
and locking valve.
This pressure is applied to check valve and oscillating cylinder, thus the oscillating function is
operated (Ram lock released).

3-28