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3-20
3-20
When the LH 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.
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. Also the swing operation preference function is operated by the pilot pressure PSp
(refer to page 3-12).
7. SWING OPERATION
PS
(P4)
(P3)
N2
Pca
Dr3
P2c2
Ba
Aa
PAa
PBa
Bo
Ao
PAo
PBo
(Ck2)
Drb
PBb2
PSp
Dra
Bs
As
PAs
PBs
Dr4
Pns
Br
Ar
PAr
PBr
R3
TRAVEL(RH)
SWING
BOOM 2
T1
Pa
P2
P1 P1g
P2g
R4
(PTb)
PS
PL1
Py
PBL
PAL
PBb
PAb
Ab
Bb
P2c1
Dr3'
PBc
PAc
PAcs
Bc
Ac
PBa2
PAa2
Pcb
N1
OPTION
ARM 1
ARM 2
BUCKET
BOOM 1
TRAVEL(LH)
PS
PS
PS
PS
PS
A
B
C
TRAVEL
P
T
RCV PEDAL
(2)
PBr
(1)
PAr
(4)
PBL
(3)
PAL
BOOM
P
T
BUCKET
ARM
P
T
SWING
c
e2
d1
h1
h2
P2c1
PAb
(4)
PBc
Pca
PAc
PAcs
PBb2
PBb
PAa2
P2c2
PAa
PBa2
PBa
PBs
PAs
PSp
Dr#,dr#
T
LINE FILTER
P3
P2
P1
P4
Pns
(MCV)
PL1
(MCV)
P
(T/Joint)
A1
A2
A4
A5
SH
(2)
(1)
(3)
(4)
(2)
(3)
(1)
HYDRAULIC TANK
SH
PG
ARG
Dr
GA
A(CCW)
Mu
B(CW)
GB
Au
SGo
(RG)
Dr
SRG
TRAVEL MOTOR
SWING MOTOR
ARM
CYLINDER
BUCKET
CYLINDER
BOOM
CYLINDER
PILOT
PUMP
BL
AL
Px
P
PG(S/Motor)
Pa(MCV)
Psv1(M/PUMP)
P(MCV)
B
a
b
d
e
f
g
h
j
PUMP
A1
PUMP
A2
A
D
E
F
G
H
J
380L3HC16