3-31
3-31
When the bucket and travel functions are operated simultaneously, the bucket spool and travel
spools in the main control valve are moved to the functional position by the pilot oil pressure from the
remote control valve, and the straight travel spool is pushed to the right by the oil pressure from pilot
pump. The oil from the A1 pump flows into the travel motors through the RH travel spool of the left
control valve and the LH travel spool of the right control valve via the straight travel spool of the
control valve.
The oil from the A2 pump flows into the bucket cylinder through the bucket spool via the confluence
oil passage.
When the pressure of the travel motors is lower than the pressure of the bucket cylinder, some oil
from the A2 pump flows into the travel motors through the check valve and orifice in the straight
travel spool. This prevents the rapid slowdown of the travel.
The bucket is operated and the machine travels straight.
8. COMBINED BUCKET AND TRAVEL 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
TRAVEL(RH)
SWING
BOOM 2
T1
Pa
P2
P1 P1g
P2g
R4
(PTb)
PS
PL1
Py
PBL
PAL
BL
AL
Px
P
PBb
PAb
Ab
Bb
P2c1
Dr3'
PBc
PAc
PAcs
Bc
Ac
PBa2
PAa2
Pcb
N1
OPTION
ARM 2
BUCKET
BOOM 1
TRAVEL(LH)
SH
HYDRAULIC TANK
STRAIGHT
TRAVEL
SPOOL
ARM 1
TRAVEL MOTOR
SWING MOTOR
ARM
CYLINDER
BUCKET
CYLINDER
BOOM
CYLINDER
PILOT
PUMP
R3
PUMP
A1
PUMP
A2
380L3HC27