©
2003 Caterpillar
All Rights Reserved
Printed in U.S.A.
This attachment schematic is to be used in conjunction with the Standard Schematic in this Service Manual.
RENR7081
May 2003
375 Excavators
One Way Flow
6NK156-UP
9WL132-UP
Hydraulic System - Attachment
ONE POSITION
TWO POSITION
THREE POSITION
VENTED
PRESSURIZED
RETURN ABOVE FLUID LEVEL
RETURN BELOW FLUID LEVEL
LINES CROSSING
LINES JOINING
TWO-WAY
THREE-WAY
FOUR-WAY
SPRING
CONTROL VALVES
RESTRICTION
LINE RESTRICTION
(FIXED)
2-SECTION PUMP
MAIN
AUX.
SPRING
(ADJUSTABLE)
VARIABILITY
LINE RESTRICTION
(VARIABLE)
LINE RESTRICTION
(VARIABLE and PRESSURE COMPENSATED)
PRESSURE
COMPENSATION
PUMP: VARIABLE and
PRESSURE COMPENSATED
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
MEASUREMENT
PRESSURE
TEMPERATURE
FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH-PULL LEVER
PEDAL
GENERAL MANUAL
PUSH BUTTON
SPRING
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
HYDRAULIC PUMPS
FLUID STORAGE RESERVOIRS
CROSSING AND JOINING LINES
VALVE ENVELOPES
VALVE PORTS
BASIC COMPONENT SYMBOLS
FLUID CONDITIONER
PUMP or MOTOR
FLUID POWER SYMBOLS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVES
PILOT CONTROL SYMBOLS
RELEASED PRESSURE
EXTERNAL RETURN
INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED
COMPLETE
INTERNAL
SUPPLY PRESSURE
ACCUMULATORS
SPRING LOADED
GAS CHARGED
SOLENOID
or MANUAL
SOLENOID
and PILOT
SOLENOID and
PILOT or MANUAL
COMBINATION CONTROLS
SOLENOID
SERVO
THERMAL
DETENT
HYDRAULIC AND PNEUMATIC CYLINDERS
DOUBLE ACTING
SINGLE ACTING
BASIC SYMBOL
SPRING LOADED
CHECK VALVES
TWO
POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW ALLOWED IN
EITHER DIRECTION
THREE
POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
A B
P T
A B
P T
SHIFTED POSITION
INFINITE POSITION
CONTROL VALVES
BL2
T
P
C
R
aL2
B1
bL2
R
C
P
T
T
P
R
SINGLE
UPDOWN DOWN UP UP
Dr
Pi
P2
T
P1
aR3
aL3
bR3
bL3
aL1
aR1
JL3
JL1
JR1
JR3
JR2
TRT
TLP
TLA1
TLA2
bL4
aL4 bR1
bL1
SBT2BSA
T2A
MA
G
A
ST2
MA
A
GBZB
PILOT
PUMP
REAR PUMP
FRONT PUMP
SWING PUMP
TRA2
TRA1
TRP
TLT
(CLOSE)
Pi
R
DD
RIGHT
M
Pb
AMBM
BM
AM
Pb
G
G
ZA
X
X
STICK CYLINDER BOOM CYLINDERBUCKET CYLINDER
PR
PR
PG
PG
SWIVEL
SWING
MB
SHSH
D
D
F
F
E
E
P
T
M2
M1
BGA
R2
LEFT
TRACK
A2
DR5
AL2
BL3
AL3
BR3 AR3
M
JPd
Jd
JPg
JP1
LS
PR
PF
AL4
(OPEN)
(UP)
BL4 BR1
AR1
JL2
JL4
Pi1 Pi2 Pi3
DR1
DR2
DR3
X
ATT
TOUT
PIN
PG
DR4
Pi4
BL1
AL1
IMP2
PSW
PTA
TRBM1DS
dR1
BM2IMP1
JR4
A3
A4
A5
A1
S
P
T
B2
B3
XA
MZA
XB
MZB
T
T
P
SD1
P
A
B4
B5
HL1
Z
Y
(DOWN)(CLOSE)
(OPEN)
STICKSWING
BOOMBUCKET
TRAVEL(R)
TRAVEL(L)
R1
STICK
BUCKET
PD
P1
T
P2Pi
Dr
X
PD
BOOM
TRAVEL(L)
TRAVEL(R)
PILOT LINE
DRAIN LINE
This Attachment Schematic is intended to
be used in conjunction with the Standard
Hydraulic Schematic in this Service Manual.
Hydraulic Schematic
MAIN CONNECTOR LINE
113-4084
1
2
3
4
5
6
7
1
Item
No.
Description
ATTACHMENT COMPONENTS
2
3
4
5
6
7
E
E
M
M
N
J
J
H
88.0
`2.0
1
1
2
2
3
3
4
4
6
6
Relief Valves
Shuttle Valve
Valve Group - Solenoid and Relief
Check Valve
Pressure Reducing Valve
Valve Group - Solenoid and Relief
Check Valve
g01001901
