UENR3879-00
30 Page, (Dimensions: 39 inches x 28 inches)
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
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
Electrical Symbols (Electrical)
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
AB
PT
AB
PT
SHIFTED POSITION
INFINITE POSITION
CONTROL VALVES
ATTACHM ENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
T
UENR3879
November 2012
444F Backhoe Loader
Hydraulic System
LJJ1-UP
FBN1-UP
Printed in U.S.A.© 2012 Caterpillar, All Rights Reserved
Description Part Number
Machine
Location
Schematic
Location
IMPLEMENT PUMP GP 307-3069 1 B-4
HYDRAULIC TANK 358-9301 2 A-5
TANK GROUP 351-5888 3 A-5
HYDRAULIC COOLER 337-9751 4 B-4
HYDRAULIC FILTER 359-7232 5 B-3
HMU 341-7654 6 C-6
STEER CYL-FRONT 217-5097 7 B-6
LH:
374-8060
RH:
374-8059
TILT CYL (PL/IT) 370-7083 9 B-8
MP BUCKET CYL (OPT) 185-1839 10 A-8
F-6
F-3
BOOM CYL 320-6522 12 F-6
STICK CYL 320-6523 13 F-4
LH:
381-8055
RH:
381-8054
BUCKET CYL 320-5937 15 F-4
E-STICK CYL (OPT) 320-5935 16 F-3
ACCUMULATOR (PILOT) 226-0420 17 C-5
RIDE CNTRL VALVE (OPT) 245-8780 18 C-8
RIDE CNTRL ACC (OPT) 382-8033 19 C-8
RIDE CNTRL SENSOR (OPT) 344-7391 20 C-8
TEMP SENSOR (OPT) 264-4297 21 C-4
DIFF PRES SWITCH (OPT) 134-0404 22 C-4
COUPLER VALVE (LDR) 359-7228 23 A-8
COUPLER CYL (LDR) 178-3713 24 A-8
LOADER VALVE (PL/IT) 359-7211 2
5C-7
BACKHOE VALVE 359-7216 26 F-7
PATTERN CHANGING VALVE 300-4491 27 D-6
SWING CUSHION VALVE 320-7812 28 F-5
F-3
F-6
F-2
F-8
VALVE GP-PILOT (LDR) 382-4996 31 D-7
STD:
359-7246
W/SWITCH 359-7247
DTNT and SWITCH: 359-7248
PILOT MANIFOLD (BASIC +4) 359-7224 33 D-4
PUMP DISCHARGE PRES SNSR 344-7391 34 C-5
BOOSTED BRAKE VALVE 220-8226 35 D-3
ALL WHEEL STEER VALVE
(NOT SHOWN)
373-6998 36 A-6
HOSE BURST CHECK VALVE
(BOOM) 347-1128 37 F-6
HOSE BURST CHECK VALVE (STICK) 347-1129 38 F-4
HOSE BURST CHECK VALVE (LIFT) 262-7081 39 B-8
HOSE BURST CHECK VALVE (TILT) 262-7079 40 B-8
POWERED SIDESHIFT VALVE 351-1637 41 B-2
POWERED SIDESHIFT CYL 347-2223 42 F-1
8TH AUXILIARY VALVE 319-2155 43 E-1
8TH AUXILIARY PILOT VALVE 373-7028 44 D-1
9TH AUXILIARY VALVE 319-2158 45 D-2
9TH AUXILIARY PILOT VALVE 373-7029 46 C-1
COUPLER VALVE (
HOE) 358-2091 47 A-3
COUPLER CYLINDER (HOE) 361-1139 48 B-3
VALVE - CHECK 424-2971 49 C-6
COMPONENT LOCATIONS
8B-8
STABILIZER CYL
SWING CYL 14 F-5
LIFT CYL
VALVE GP-PILOT (STAB) 32 E-8
320-5938 11
VALVE GP-PILOT (HOE) 359-7227 30
308-3437 29STAB CHECK VALVE
BOTTOM
LEFT
RIGHT
STICK + E STICK
= Graphic not avalible at time of publication.
Tap Number Description
Schematic
Location
T1 PUMP DISCHARGE PRESSURE C-5
T2 RIGHT REAR SERVICE BRAKE (See Volume 3) C-4
T3 REAR PARK BRAKES (See Volume 3) D-5
TAP LOCATIONS
Pressure, Sampling, Sensor
(NOT SHOWN)
MACHINE VIEWS
11
11
41
29
29
26
43
44
45
32
25
698
4983213130
T1
40 39
40 39
35
18 19 5
42
14
27
28 47
48 24
23
17
15
38
16
12
37
10
10
13
34
T3 T2
2021
22
49
14
46
33
7
UENR3879-00
30 Page, (Dimensions: 39 inches x 28 inches)
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling,Sensor) by letter
Components by number
YY
52
444F BACKHOE LOADER HYDRAULIC SCHEMATIC
MEDIA NUMBER: UENR3879-00
PART NUMBER: 362-9207, CHANGE: 02, VERSION: --
Components are shown installed on a fully operable machine.
Refer to the appropriate Service Manual for Troubleshooting, Specifications.
DRAIN / RETURN LINE
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
IMPLEMENT AND STEERING PUMP CIRCUIT
SWING CYLINDER CIRCUIT
STEERING CYLINDER CIRCUIT
PILOT OIL CIRCUIT
BUCKET CYLINDER CIRCUIT
STICK CYLINDER CIRCUIT
LOAD SENSE CIRCUIT
SUPPLY LINE
BACKHOE VALVE AUX CIRCUIT
E-STICK CYLINDER CIRCUIT
BOOM CYLINDER CIRCUIT
STABILIZER CYLINDER CIRCUIT
BOOSTED BRAKE OIL CIRCUIT
LIFT CYLINDER CIRCUIT
TILT CYLINDER CIRCUIT
LOADER VALVE CIRCUIT
POWER SIDE-SHIFT CYLINDER CIRCUIT
SIDE-SHIFT LOCK CYLINDER CIRCUIT
COUPLER CIRCUIT (HOE)
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
359-7227
320-5935
320-5938
308-3437
320-6523
381-8054
381-8055
320-5937
347-1129
320-7812
320-5938
320-6522
308-3437
347-1128
359-7216
359-7227
359-7247
359-7248
359-7246
319-2155
347-2223
373-7028
373-7028
373-7029
347-2223
351-1637
359-7232
134-0404
264-4297
307-3069
344-7391
347-2223
358-2091
351-5888
358-9301
214-5079
373-6998
370-7083
185-1839
178-3713
359-7228
262-7079
359-7211
344-7391
382-8033
245-8780
374-8060
262-7081
374-8059
226-0420
341-7654
424-2971
220-8226
359-7224
300-4491
382-4996
337-9751
D
DLS
LIFT
TILT
AUX
FRONT STEER CYL.
ACC
R
T
PS
H
RH STAB
BOOM
SWING
BUCKET
STICK
LH STAB
E-STICK
A4
B4
B3
A6
B6
A1
B1
LB
LA
TA
TB
LAB
LAA
RS2
RS1
BA
BB
R4
R2
SB
SA
LS1
LS2
EA
EB
J1
J2 T2 T3 J3
T1
P ACC DIAG
OPERATOR LEFT JOYSTICK
OPERATOR
LEFT
OPERATOR
RIGHT
STABILIZER JOYSTICK
TILT
LIFT
LOADER JOYSTICK
P
LAA
EB
LAB
EA
TBTALALB
LS2
LS1
RS2
RS1
L1L3L2L4
R2R4R3R1
SBBABB SA
L4R1 R3 L2
A1
B1
A2
B2
A3
B3
A3
BRK
LEFT
BRAKE
PEDAL
TO REAR AXLE
LEFT WHEEL
BRAKE
TO REAR AXLE
RIGHT WHEEL
BRAKE
S
U
LIFT
TILT
AUX
A2
B2
A5
B5
A7
B7
Pil
BL
C2
V2
Pil
BL
C2
V2
SIDESHIFT
LOCK
R
L
B
A
P8
LS8
T8
T7
P7
T6
P6
B
A
L1
L3
OPERATOR RIGHT JOYSTICK
RIGHT
BRAKE
PEDAL
(3) TANK GROUP - FILTER / BREATHER / SIGHT GAGE
(2) TANK - HYDRAULIC
(4) COOLER - HYDRAULIC
(1) PUMP GP - IMPLEMENT
(7) CYLINDER - FRONT STEER
(36) VALVE GP - AWS
(5) FILTER - HYDRAULIC
(22) SWITCH - DIFF PRESS
(OPTIONAL)
(21) SENSOR - TEMP
(OPTIONAL)
(37) VALVE - BOOSTED BRAKE
(33) MANIFOLD - PILOT (BASIC +4)
(17) ACCUMULATOR - PILOT
(34) SENSOR -
PUMP DISCHARGE
(6) VALVE HMU - LOAD SENSE RELIEF
(27) VALVE - PATTERN CHANGE
(31) VALVE GP - PILOT
(25) VALVE - LOADER (PL/IT)
(20) SENSOR -
RIDE CONTROL (OPT)
(19) ACCUMULATOR - OPTIONAL
(18) VALVE - RIDE CONTROL (OPT)
(8) CYLINDER - LIFT
(9) CYLINDER - TILT
(10) CYLINDER -
MP BUCKET (OPT)
(24) CYLINDER - COUPLER
(23) VALVE - COUPLER (LDR)
(32) VALVE GP - PILOT (HOE)
(16) CYLINDER - E STICK
(OPT)
(12) CYLINDER - STAB
(31) VALVE - CHECK (STAB)
(13) CYLINDER - STICK
(14) CYLINDER - SWING
LH:
RH:
(15) CYLINDER - BUCKET
(38) VALVE - STICK
HOSE BURST
(28) VALVE - CUSHION
(11) CYLINDER - STAB
(12) CYLINDER - BOOM
(29) VALVE -
CHECK (STAB)
(37) VALVE - BOOM
HOSE BURST
(26) VALVE - BACKHOE
(40) VALVE - TILT
HOSE BURST
(39) VALVE - LIFT
HOSE BURST
(30) VALVE GP - PILOT (HOE)
(32) VALVE GP - PILOT (STAB)
W / SWITCH:
DTNT and SWITCH:
9TH AUX
A2B2
PSS
A1B1
8TH AUX
A2B2
T2
LS2
P2
LSTMP
8TH AUXILIARY & POWERED SIDESHIFT
P8
LS8
T8
T6
P6
C2C1
P
T
T6
P6
T8
P8
LSC1 C2
P
T
POWERED SIDESHIFT
LS8
BACKHOE COUPLER
T7
P7
9TH AUXILIARY
(44) VALVE - PILOT
8TH AUX
(45) VALVE - 9TH AUX
(43) VALVE - 8TH AUX
(45) CYLINDER - POWER SIDE SHIFT
(46) VALVE - PILOT
9TH AUX
(42) CYLINDER -
POWER SIDE SHIFT
(41) VALVE -
POWER SIDE SHIFT
(47) VALVE - COUPLER
(HOE)
(48) CYLINDER -
COUPLER (HOE)
ADDED AS AN ADDITONAL SLICE TO
8TH and POWERED SIDESHIFT VALVE
F1
F2
R2
R1
REAR STEER CYLINDER
FRONT STEER CYL.
AWS VALVE
HMU-R
HMU-L
OPTIONAL ATTACHMENT
OPTIONAL ATTACHMENT
(49) VALVE - CHECK
LH:
RH:
OPTIONAL ATTACHMENT
STD:
OPTIONAL ATTACHMENT
(33) MANIFOLD - PILOT (BASIC +4)
T2
T1
T3
