UENR3880
November 2012
434F Backhoe Loader
Hydraulic System
434F:
LDH1-UP
FLY1-UP
Printed in U.S.A.© 2012 Caterpillar, All Rights Reserved
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)
PUMP
(2 - SECTION)
SPRING
(ADJUSTABLE)
VARIABILITY LINE RESTRICTION
(VARIABLE)
PRESSURE
COMPENSATION
PUMP
(VARIABLE & PRESSURE
COMPENSATED)
MEASUREMENT
PRESSURE TEMPERATURE FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH - PULL LEVER PEDALGENERAL MANUAL PUSH BUTTON SPRING
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVE ENVELOPES VALVE PORTS
FLUID CONDITIONERPUMP OR MOTOR
FLUID POWER SYMBOLS
UNIDIRECTIONAL
BIDIRECTIONAL
RELEASED PRESSURE
EXTERNAL RETURN INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED
HYDRAULIC PUMPS
ACCUMULATORS
SPRING LOADED GAS CHARGED
SOLENOID
OR MANUAL
SOLENOID
& PILOT
SOLENOID &
PILOT OR MANUAL
SOLENOID SERVO THERMAL DETENT
HYDRAULIC & PNEUMATIC CYLINDERS
DOUBLE ACTINGSINGLE ACTING
BASIC
SYMBOL
SPRING
LOADED
CHECK VALVES
2 POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW IN
EITHER
DIRECTION
3 POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
AB
PT
AB
PT
SHIFTED POSITION INFINITE POSITION
CONTROL VALVES
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
MAIN AUX
LINE RESTRICTION
(VARIABLE & PRESSURE
COMPENSATED)
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FLUID STORAGE RESERVOIRS
CROSSING & JOINING LINES
VALVES
PILOT CONTROL SYMBOLS
COMBINATION CONTROLS
BASIC COMPONENT SYMBOLS
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
INTERNAL
SUPPLY PRESSURE
COMPLETE
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
HYDRAULIC SYMBOLS (ELECTRICAL)
ELECTRICAL SYMBOLS TABLE
325-AG135 PK-14
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
WIRE
WIRE
(EXAMPLE VALVE)
CURRENT STANDARD
TRANSDUCER
(FLUID)
M
ELECTRIC MOTORTRANSDUCER
(GAS / AIR)
G
GENERATOR
PRESSURE SWITCH ELECTRICAL WIREPRESSURE SWITCH
(ADJUSTABLE)
TEMPERATURE
SWITCH
PRESSURE
SWITCH
TEMPERATURE
SWITCH
LEVEL
SWITCH
FLOW
SWITCH
ELECTRICAL SYMBOLS (ELECTRICAL)
A
CIRCUIT NUMBER
IDENTIFICATION
WIRE
COLOR
WIRE GAUGE
UENR3880-00
30 Page, (Dimensions: 39 inches x 28 inches)
* COMPONENTS NOT SHOWN
25
15
5
19
26
16
18
27
22
1
4
28
29
2
6
7
9
8
14
1312
11
20
21
24
30
31
3
26
17
T3
T2
T1
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
FRONT VIEW: 1
BOOM WITH E-STICK
REAR MACHINE VIEW
UNDER CAB VIEW
FRONT VIEW: 2
Description
Part
Number
Machine
Location
Schematic
Location
Pump GP -Implement 307-3063 1 B-5
Tank -Hydraulic 358-9301 2 A-5
TANK GROUP -Filter/ Breather / Sight Gage 351-5888
3A-5
Cooler -Hydraulic 337-9751 4 B-4
Filter -Hydraulic 361-6768 5 B-3
Valve HMU -Load Sense Relief 341-7654 6 C-6
Cylinder -Front Steer 217-5097 7 B-6
LH: 374-8060
RH: 374-8059
Cylinder -Tilt 370-7083 9 B-8
Cylinder -MP Bucket (OPT) 185-1839 10* A-8
Cylinder -Stab 320-5938 11 F-6
Cylinder -Boom 320-5936 12 F-6
Cylinder -Stick 320-5932 13 F-4
LH: 381-8055 F-5
RH: 381-8054
Cylinder -Bucket 320-5937 15 F-4
Cylind
er -E-Stick (OPT) 320-5935 16 F-3
Accumulator -Pilot 149-0686 17 D-5
Valve -Ride Control (OPT) 245-8780 18 C-8
Accumulator -Optional 382-8033 19 C-8
Sensor -Ride Control (OPT) 344-7391 20 C-8
Valve -Loader (PL/IT) 359-7209 21 C-7
Valve -Backhoe 359-7214 22 F-7
Valve -Cushion 320-7812 23* F-5
Valve -Check (Stab) 308-3437 24 F-6
Valve -Boosted Brake 220-8226 25 D-3
Manifold -Brake 373-6966 26 D-5
Valve GP -AWS
373-6998 27 A-5
Valve -Boom Hose Burst 389-3096 28 F-6
Valve -Stick Hose Burst 347-1127 29 F-4
Valve -Lift Hose Burst 262-7081 30 B-8
Valve -Tilt Hose Burst 262-7079 31 B-8
Valve -Power Side Shift 351-1637 32* B-2
Cylinder -Power Side Shift 347-2223 33* B-3
Valve -Coupler (HOE) 358-2091 34* A-3
Cylinder -Coupler (HOE) 361-1139 35* B-3
Solenoid - Object Lifting 332-6408 36* X-X
Valve - Check (Dual Back Pressure
) 424-2971 37* X-X
Cylinder -Swing
8
14
Cylinder -Lift B-8
COMPONENT LOCATIONS
UENR3880-00
30 Page, (Dimensions: 39 inches x 28 inches)
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
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
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)
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
YY
(52) VALVE GP - CONTROL
138-1234
Callout Number
(Machine Location from
Component LocationsTable)
Component
Name
Part Number
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: 362-9204, CHANGE: 02, VERSION: -
434F BACKHOE LOADER HYDRAULIC SYSTEM SCHEMATIC
MEDIA NUMBER: UENR3880
T2
T1
T3
(3) TANK GROUP - FILTER / BREATHER / SIGHT GAGE
(2) TANK - HYDRAULIC
(4) COOLER - HYDRAULIC
(1) PUMP GP - IMPLEMENT
(7) CYLINDER - FRONT STEER
(27) VALVE GP - AWS (434F ONLY)
(5) FILTER - HYDRAULIC
(25) VALVE - BOOSTED BRAKE
(26) MANIFOLD - BRAKE
(17) ACCUMULATOR - PILOT
(6) VALVE HMU - LOAD SENSE RELIEF
(26) VALVE - LOADER (ST)
(20) SENSOR -
RIDE CONTROL (OPT)
(19) ACCUMULATOR - OPTIONAL
(18) VALVE - RIDE CONTROL (OPT)
(8) CYLINDER - LIFT
(9) CYLINDER - TILT
(10) CYLINDER -
MP BUCKET (OPT)
(16) CYLINDER - E STICK
(OPT)
(12) CYLINDER - STAB
(31) VALVE - CHECK (STAB)
(13) CYLINDER - STICK
(14) CYLINDER - SWING
(15) CYLINDER - BUCKET
(29) VALVE - STICK
HOSE BURST
(23) VALVE - CUSHION
(13) CYLINDER - STAB
(12) CYLINDER - BOOM
(24) VALVE -
CHECK (STAB)
(28) VALVE - BOOM
HOSE BURST
(22) VALVE - BACKHOE
(31) VALVE - TILT
HOSE BURST
(30) VALVE - LIFT
HOSE BURST
(33) CYLINDER -
POWER SIDE SHIFT
(32) VALVE -
POWER SIDE SHIFT
(34) VALVE - COUPLER
(HOE)
(35) CYLINDER -
COUPLER (HOE)
(21) VALVE - LOADER (PL/IT)
(36) SOLENOID - OBJECT LIFTING
(37) VALVE - CHECK
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
P
A1
B1
A2
B2
A3
B3
A3
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
SIDESHIFT
LOCK
F1
F2
R2
R1
REAR STEER CYLINDER
FRONT STEER CYL.
AWS VALVE 434F ONLY
HMU-R
HMU-L
R
L
B
A
NOTE B
P8
LS8
T8
T7
P7
B
A
RIGHT
BRAKE
PEDAL
LH:
RH:
T8
P8
LSC1 C2
P
T
POWERED SIDESHIFT
LS8
BACKHOE COUPLER
T7
P7
T
P
P
V2
C2
T
V2
PIL
BL
351-5888
358-9301
337-9751
307-3063
214-5097
373-6998
361-6768
220-8226
373-6966
149-0686
341-7654
359-7203
382-8033
245-8780
370-7083
185-1839
320-5935
320-5938
308-3437
320-5932
381-8054
381-8055
320-5937
347-1127
320-7812
320-5938
320-5936
308-3437
389-3096
359-7214
262-7079
262-7081
347-2223
351-1637
358-2091
347-2223
374-8060LEFT:
344-7391
374-8059RIGHT:
359-7209
(16) CYLINDER - E STICK
(OPT)
(12) CYLINDER - STAB
(31) VALVE - CHECK (STAB)
(13) CYLINDER - STICK
(14) CYLINDER - SWING
(15) CYLINDER - BUCKET
(23) VALVE - CUSHION
(11) CYLINDER - STAB
(12) CYLINDER - BOOM
(24) VALVE -
CHECK (STAB)
(28) VALVE - BOOM
HOSE BURST
(22) VALVE - BACKHOE
(3) TANK GROUP - FILTER / BREATHER / SIGHT GAGE
(2) TANK - HYDRAULIC
(4) COOLER - HYDRAULIC
(1) PUMP GP - IMPLEMENT
(7) CYLINDER - FRONT STEER
(27) VALVE GP - AWS (434F ONLY)
(5) FILTER - HYDRAULIC
(25) VALVE - BOOSTED BRAKE
(26) MANIFOLD - BRAKE
(17) ACCUMULATOR - PILOT
(6) VALVE HMU - LOAD SENSE RELIEF
(33) CYLINDER -
POWER SIDE SHIFT
(32) VALVE -
POWER SIDE SHIFT
(34) VALVE - COUPLER
(HOE)
(35) CYLINDER -
COUPLER (HOE)
(26) VALVE - LOADER (ST)
(20) SENSOR -
RIDE CONTROL (OPT)
(19) ACCUMULATOR - OPTIONAL
(18) VALVE - RIDE CONTROL (OPT)
(8) CYLINDER - LIFT
(9) CYLINDER - TILT
(10) CYLINDER -
MP BUCKET (OPT)
(31) VALVE - TILT
HOSE BURST
(30) VALVE - LIFT
HOSE BURST
(21) VALVE - LOADER (PL/IT)
T2
T1
T3
OPTIONAL ATTACHMENT
OPTIONAL ATTACHMENT
OPTIONAL ATTACHMENT
424-2971
(37) VALVE - CHECK
OPTIONAL
ATTACHMENT
332-6408
(36) SOLENOID - OBJECT LIFTING
(29) VALVE - STICK
HOSE BURST
