UENR3238-01
November 2012
422F and 428F Backhoe Loader
Hydraulic System
422F:
LRH1-UP
428F:
LBH1-UP
SJW1-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
UENR3238-01
30 Page, (Dimensions: 39 inches x 28 inches)
* COMPONENTS NOT SHOWN
37
16
5
20
26
17
19
39
28
1
49
40
41
2
6
7
10
8
15
1413
12
21
27
31
42
43
3
38
18
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
428F-434F FRONT VIEW 422F FRONT
BOOM WITH E-STICK
REAR MACHINE VIEW
UNDER CAB VIEW
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 3 A-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 422F, 428F: 358-5034
RH 422F, 428F: 358-5035
Cylinder - Tilt 422F: 358-5044 9 A-8
Cylinder - Tilt
428F: 358-5045
10 B-8
Cylinder - MP Bucket (OPT) 185-1839 11* A-8
Cylinder - Stab 320-5938 12 F-6
320-5936
320-6521
LH: 381-8055
RH: 381-8054
Cylinder - Bucket 320-5937 16 F-4
Cylinder - E-Stick (OPT) 32
0-5935 17 F-3
Accumulator - Pilot 149-0686 18 D-5
Valve - Ride Control (OPT) 245-8780 19 C-8
Accumulator - Optional 382-8033 20 C-8
Sensor - Ride Control (OPT)
422F:
428F:
304-5696
344-7391
21 C-8
Valve - Loader (ST) 422F: 359-7203 26 C-7
Valve - Loader (PL/IT) 428F: 359-7209 27 C-7
Valve - Backhoe 359-7214 28 F-7
Valve - Cushion 320-7812 30 F-5
Valve - Check (Stab) 308-3437 31 F-6
Valve - Boosted Brake 220-8226 37 D-3
Manifold - Brake 373-6966
38 D-5
422F, 428F: N/A
Valve - Boom Hose Burst 428F: 347-1126 40 F-6
Valve - Stick Hose Burst 428F: 347-1127 41 F-4
Valve - Lift Hose Burst 428F: 262-7081 42 B-8
Valve - Tilt Hose Burst 428F: 262-7079 43 B-8
Valve - Power Side Shift 428F: 351-1637 44* B-2
Cylinder - Power Side Shift 428F: 347-2223 45* B-3
Valve - Coupler (HOE) 358-2091 50* A-3
Cylinder - Coupler (HOE) 361-1139 51* B-3
COMPONENT LOCATIONS
8Cylinder - Lift
13 F-6Cylinder - B
oom
B-8
Valve GP - AWS 39 A-5
Cylinder - Stick 14 F-4
15 F-5Cylinder - Swing
UENR3238-01
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: 01, VERSION: -
THIS SCHEMATIC IS FOR THE 422F AND 428F BACKHOE LOADER HYDRAULIC SYSTEM
MEDIA NUMBER: UENR3238-01
T2
T1
T3
(3) TANK GROUP - FILTER / BREATHER / SIGHT GAGE
(2) TANK - HYDRAULIC
(4) COOLER - HYDRAULIC
(1) PUMP GP - IMPLEMENT
(7) CYLINDER - FRONT STEER
(39) VALVE GP - AWS (434F ONLY)
(5) FILTER - HYDRAULIC
(37) VALVE - BOOSTED BRAKE
(38) MANIFOLD - BRAKE
(18) ACCUMULATOR - PILOT
(6) VALVE HMU - LOAD SENSE RELIEF
(26) VALVE - LOADER (ST)
(21) SENSOR -
RIDE CONTROL (OPT)
(20) ACCUMULATOR - OPTIONAL
(19) VALVE - RIDE CONTROL (OPT)
(8) CYLINDER - LIFT
(10) CYLINDER - TILT
(11) CYLINDER -
MP BUCKET (OPT)
(17) CYLINDER - E STICK
(OPT)
(12) CYLINDER - STAB
(31) VALVE - CHECK (STAB)
(14) CYLINDER - STICK
(15) CYLINDER - SWING
(16) CYLINDER - BUCKET
(41) VALVE - STICK
HOSE BURST
(30) VALVE - CUSHION
(12) CYLINDER - STAB
(13) CYLINDER - BOOM
(31) VALVE -
CHECK (STAB)
(40) VALVE - BOOM
HOSE BURST
(28) VALVE - BACKHOE
(43) VALVE - TILT
HOSE BURST
(42) VALVE - LIFT
HOSE BURST
(45) CYLINDER -
POWER SIDE SHIFT
(44) VALVE -
POWER SIDE SHIFT
(50) VALVE - COUPLER
(HOE)
(51) CYLINDER -
COUPLER (HOE)
(9) CYLINDER - TILT
(27) VALVE - LOADER (PL/IT)
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
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
340-7028
361-6768
220-8226
373-6966
149-0686
341-7654
359-7203
382-8033
245-8780
358-5045
370-7083
428F:
434F:
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
347-1126
359-7214
262-7079
262-7081
347-2223
351-1637
358-2091
347-2223
358-5044422F:
358-5034
374-8060
422F, 428F LEFT:
434F LEFT:
304-5696
344-7391
422F:
428F, 434F:
358-5035
374-8059
422F, 428F RIGHT:
434F RIGHT:
359-7209
