INTERACTIVE SCHEMATIC
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Cover Page
Information
Schematic
Machine Views
Component Table
Tap Table
Fluid Power Symbols
Electrical Symbols
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Rear Frame
Tap Views
Features
Options
Bookmarks
X
EC-C3
EC-C2
E-C60
EC-C1
E-C61
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©
2012 Caterpillar, All Rights Reserved
Printed in U.S.A.
UENR3614
August 2012
424B Backhoe Loader
Hydraulic System
JRC5546-UP
Printed in U.S.A.© 2012 Caterpillar, All Rights Reserved
Media Info / Publication Routing
NPI/CPI/Revision/Remedy/Fix and Due Date
X
Color or B/W
Color
Volumes/Total Pages
V1 V2 V3 V4
Initials Date
Author/Submission Date
Glorindha 9-Aug-2012
Initial Checking/Publication (Dave B./Matt)
Todd's Publishing Check
Matt's Initial Send to SIS
Returned to Author for NGS Completion
Author NGS Submission Date (Corey/Dave M.)
NGS to SIS Publication
30Pg X XX
COMPONENT LOCATION
Description
Part
Number
Machine
Location
Schematic
Location
Cylinder Gp - Boom 236-4724 1 E-4
Cylinder Gp - Bucket 228-2783 2 E-3
Cylinder Gp - Lift 236-4722 3 E-7
Cylinder Gp - Stabilizer 324-6560 4 E-1, E-5
Cylinder Gp - Steering (Front) 328-7250 5 F-8
Cylinder Gp - Stick 324-8372
6
E-2
Cylinder Gp - Swing (LH) 236-4720 7 E-3
Cylinder Gp - Swing (RH) 236-4719 8 E-3
Cylinder Gp - Tilt 236-4723 9 E-6
Filter - Oil (Hydraulic) 126-1817 10 A-6
Pump Gp - Metering (HMU) 210-6240 11 F-8
Pump Gp - Piston (Hydraulic) 312-3044 12 B-3
Radiator Gp - Oil Cooler 371-8641 13 A-5
Tank Gp - Hydraulic 240-9721 14 A-5
Valve Gp - Backhoe 311-7960 15 D-5
Kit - Cartridge 257-0477 16 D-1
Manifold Gp - Control (Outlet) 308-2154 17 D-1
Valve Gp - Control (Boom) 335-6321 18 D-4
Valve Gp - Control (Bucket) 335-6323 19 D-3
Valve Gp - Control (Stabilizer) 335-6320 20 D-1, D-5
Valve Gp - Control (Stick) 335-6324 21 D-2
Valve Gp - Control (Swing) 335-6322 22 D-3
Valve Gp - Relief (Boom) 335-6768 23 D-4
Valve Gp - Relief (Bucket) 335-6768 24 D-3
Valve Gp - Relief (Stick) 335-6767 25 D-2
Valve Gp - Relief (Swing) 335-6767 26 D-3
Valve Gp - Bank 2 311-7958 27 D-6
Manifold Gp - Control 332-4168 28 C-7
Valve Gp - Control (Lift) 332-4145 29 C-7
Valve Gp - Control (Tilt) 332-4146 30 C-6
Valve Gp - Relief (Flow Control) 332-7489 31 C-6
Valve Gp - Check 322-9859 32 A-6
Check Part Numbers in the Parts Manuals for your Specific Machine
TAP LOCATION
Tap
Number
Description
Schematic
Location
AA Pump Pressure C-3
BB Marginal Pressure D-8
FLUID POWER SYMBOLS
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
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 ACTINGSINGLE 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
ELECTRICAL SYMBOLS
Hydraulic Symbols (Electrical)
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)
T
Components are shown installed on a fully operable machine with the key and engine off, transmission shifter
in neutral and with parking brake set.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations.
SCHEMATIC PART NUMBER: 368-1815, CHANGE: 01, VERSION: D
MEDIA NUMBER: UENR3614
THIS SCHEMATIC IS FOR THE 424B BACKHOE LOADER HYDRAULIC SYSTEM
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
YY
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
MAIN PUMP OUTPUT
SLIDE FRAME CLAMP CIRCUIT
BUCKET CONTROL AND BUCKET CYLINDER CIRCUIT
LOAD SENSE CIRCUIT
STEERING CIRCUIT
STICK CONTROL AND STICK CYLINDER CIRCUIT
SUPPLY LINE
BOOM CONTROL AND BOOM CYLINDER CIRCUIT
SWING CONTROL AND SWING CYLINDER CIRCUIT
DRAIN / RETURN LINE
STABILIZER CTRL AND STABILIZER CYLINDER CIRCUIT
LIFT CONTROL AND LIFT CYLINDER CIRCUIT
TILT CONTROL AND TILT CYLINDER CIRCUIT
AA
BB
a
P
L1
L
S
X
AT DFR1 CLOSED
T
LS
T
DLS
P
P
B1 A1
b
a
B
A
b
T T
B2 A2
DLSM
TILT
LS
T
R
L
HMU
SWING
a
B2
A2
B A
b
B3
A3
T
T
BOOM
b
B
A
T
T
a
a
B4
A4
B
A
b
T
T
BUCKET
a
B5
A5
B
A
b
T
T
STICK
b
a
B6 A6
C
T3
STABILIZER
b
a
B1
A1
P
LS
T
Slide Frame Clamp
(12) PUMP GP
PISTON
(HYDRAULIC)
312-3044
(17) MANIFOLD GP
CONTROL (OUTLET)
308-2154
(20) VALVE GP
CONTROL
(STABILIZER)
335-6320
(20) VALVE GP
CONTROL
(STABILIZER)
335-6320
(15) VALVE GP
BACKHOE
311-7960
(27) VALVE GP
BANK 2
311-7958
(29) VALVE GP
CONTROL
(LIFT)
332-4145
(30) VALVE GP
CONTROL
(TILT)
332-4146
(31) VALVE GP
RELIEF
(FLOW CONTROL)
332-7489
(28) MANIFOLD GP
CONTROL
332-4168
(4) CYLINDER GP
STABILIZER
324-6560
(9) CYLINDER GP
TILT
236-4723
(3) CYLINDER GP
LIFT
236-4722
(11) PUMP GP
METERING (HMU)
210-6240
(5) CYLINDER GP
STEERING
328-7250
(1) CYLINDER GP
BOOM
236-4724
(8) CYLINDER GP
SWING (RH)
236-4719
(7) CYLINDER GP
SWING (LH)
236-4720
(2) CYLINDER GP
BUCKET
228-2783
(6) CYLINDER GP
STICK
324-8372
(4) CYLINDER GP
STABILIZER
324-6560
(16) KIT
CARTRIDGE
257-0477
(25) VALVE GP
RELIEF
(STICK)
335-6767
(26) VALVE GP
RELIEF
(SWING)
335-6767
(24) VALVE GP
RELIEF
(BUCKET)
335-6768
(23) VALVE GP
RELIEF
(BOOM)
335-6768
(23) VALVE GP
RELIEF
(BOOM)
335-6753
(21) VALVE GP
CONTROL
(STICK)
335-6324
(19) VALVE GP
CONTROL
(BUCKET)
335-6323
(22) VALVE GP
CONTROL
(SWING)
335-6322
(18) VALVE GP
CONTROL
(BOOM)
335-6321
(14) TANK GP
(HYDRAULIC)
240-9721
(13) RADIATOR GP
OIL COOLER
371-8641
(10) FILTER
OIL (HYDRAULIC)
126-1817
(32) VALVE GP
CHECK
322-9859
STABILIZER
LIFT
TWO BANK VALVE
B2
A2
B1
DLS
A1
T
LS
P
31
30
29
28
VIEW ALL CALLOUTS

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