SENR8904-01
16 Page, (Dimensions: 34 inches x 24 inches)
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 PEDALGENERAL 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
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
Hydraulic Symbols (Electrical)
Electrical Symbols Table
325-AG135 PK-14
Circuit Identification
Number
Wire Color
Wire Gauge
Harness identification code
This example indicates
wire 135 in harness "AG".
325-PK-14
Wire Gauge
Wire Color
Circuit Number
Identification
Wire Number Identification Codes
Current Standard
Previous Standard
Electrical Schematic Example
Hydraulic Schematic Example
325-PK
Wire Color
Circuit Number
Identification
B
A
Wire
Wire
(EXAMPLE VALVE)
Current Standard
Transducer
(Fluid)
Transducer
(Gas / Air)
G
Generator
Electrical Wire
Pressure Switch
M
Electric Motor
Pressure Switch
(Adjustable)
Temperature Switch
T
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
Electrical Symbols (Electrical)
©
2006 Caterpillar
All Rights Reserved
Printed in U.S.A.
Single Action
SENR8904-01
October 2006
375 Excavator
Hydraulic System - Attachment
8WJ91-UP
6NK156-UP
9WL132-UP
1JM173-UP
1
Attachment Components
Item No. Component
1 Pilot Valve
SENR8904-01
16 Page, (Dimensions: 34 inches x 24 inches)
1
2
3
4
5
6
7
9
1
2
3
4
5
6
7
A
B
A
B
C
D
E
F
C
D
E
F
3
4
56
7
3
4
56
7
A
B
C
D
E
F
A
B
C
D
E
F
1
2
8
9 8
PILOT LINE
DRAIN LINE
MAIN CONNECTOR LINE
THIS SCHEMATIC IS FOR THE 375 EXCAVATOR (ATTACHMENT)
PART #: 108-7108
Components are shown installed on a fully operable machine with the key and engine
off and transmission shifter in neutral.
This Attachment Schematic is intended to be used in conjunction with the Standard
Hydraulic Schematic in this Service Manual.
M2
Dr
Pi
P2
T
P1
aR3
aL3
bR3
bL3
aL1
aR1
JL3
JL1
JR1
JR3
JR2
(REV)
(FWD)
TRT
TLT
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
(FWD)
(REV)
TRP
TLP
(CLOSE)
PUMP CONTROL
PRESS. SWITCH
SWING 2 STEP POWER CONTROL
SOLENOID VALVE
ON : H MODE
OFF : L,SMODE
Pi
R
DD
RIGHT
M
AMBM
BM
AM
G
G
ZA
STICK CYLINDER
REAR
FRONT
BOOM CYLINDERBUCKET CYLINDER
PR
PR
PG
PG
SWIVEL
SWING
MB
SHSH
D
D
F
F
E
E
P
T
M1
BGA
REV
FWD
FWD
R2
LEFT
REV
A2
SINGLE
DR5
bL2 BL2 AL2
BL3
AL3
BR3 AR3
M
JPd
Jd
JPg
JP1
PR
PF
AL4
(OPEN)
(UP)
BL4 BR1
AR1
DS
JL2
dR1
JL4
Pi1 Pi2 Pi3
DR1
DR2
DR3
X
ATT
TOUT
PIN
PG
DR4
Pi4
BL1
AL1
IMP2
PSW
PTA
TRBM1
BM2
IMP1
aL2
JR4
A3
A4
A5
A1
S
P
B1
T
B2
B3
UPDOWN
XA
MZA
XB MZB
T
T
P
SD1
P
A2
A1
A
DOWN UP UPDOWN
B4
B5
T
P
Z
Y
(DOWN)(CLOSE)
(OPEN)
STICKSWING
BOOMBUCKET
TRAVEL(R)
TRAVEL(L)
R1
OPENOPEN
STICK
BUCKET
CLOSE
CLOSE
PD
P1
T
P2Pi
PUMP CONTROL
PRESS. SW
Dr
G
G
G
G
A
A
B
B
Pb
X
Pb
X
X
PD
HL1
LS
BOOM
TRAVEL(L)
TRAVEL(R)
TRAVEL ALARM
PRESS. S/W
ENGINE SPEED
SIGNAL
DOWN
UP
1
1
Attachment Components
Item No. Component
1 Pilot Valve
