RENR3569-04 VOL 1
20 Page
Volume 1
RENR3569-04
July 2005
420D, 430D, 432D, and 442D Backhoe
Hydraulic System
©
2005 Caterpillar
All Rights Reserved
Printed in U.S.A.
420D:
BKC1-919
BMC1-1059
BLN1-UP
430D:
BNK1-UP
BML1-UP
432D:
BLD1-UP
442D:
BRG1-UP
BRY1-UP
Volume 1: Parallel Lift, Side Shift
420D:
BKC1-919
BMC1-1059
BLN1-UP
FDP1-UP
430D:
BNK1-UP
BML1-UP
Volume 2: Single Tilt, Center Pivot
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)
Item No. Component
1 Rear Steering Cylinder (If Equipped)
2 All Wheel Steering Valve (If Equipped)
3 Steering Cylinder All Wheel Drive (If Equipped)
4 Steering Cylinder
5 Multipurpose Bucket Cylinder (If Equipped)
6 Broom Motor (If Equipped)
7 Auxiliary Control Valve
8 Coupler Cylinder
9 Coupler Valve
10 Diverter Valve
11 Tilt Cylinder
12 Line Relief Valve for Rod End of Tilt Cylinder
13 Inlet Cover
14 Auxiliary Relief Valve
15 Line Relief Valve for Head End of Tilt Cylinder
16 Steering Priority Valve
17 Two Bank Valve for Loader
18 Three Bank Valve for Loader
19 Loader Lift Control Valve
20 Loader Tilt Control Valve
21 Lift Cylinder Loader
22 Ride Control Solenoid Valve
23 Pressure Switch
24 Ride Control Accumulator
25 Steering Metering Pump
26 All Wheel Steer Pressure Switch
27 Back Pressure Check Valve (Return Oil)
28 Hydraulic Oil Filter
29 Hydraulic Oil Cooler
30 Hydraulic Tank
31 Piston Pump
32 Orifice Connector
33 Pilot Valve (Hydraulic Hand Control for the Loader)
34 Orifice Connector
35 Return Manifold
36 Solenoid Valve (Pilot Shutoff) for Hydraulic Lock Control
37 Stabilizer Control Valve (Two Bank)
38 Pressure Reducing Valve
39 Pilot Two Bank Control Valve
40 Pilot Oil Accumulator
41 Stabilizer Control Valve
42 Stabilizer Cylinder
43 Stabilizer Cylinder
44 Stabilizer Control Valve
45 Shuttle Valve
46 Inlet Cover
47 Flow Control Valve (If Equipped)
48 Boom Cylinder
49 Line Relief Valve for Rod End of Boom Cylinder
50 Line Relief Valve for Rod End on Swing Cylinder
51 Swing Cylinder
52 Swing Cylinder
53 Crossover Relief Valve (If Equipped)
54 Line Relief Valve for Head End of Bucket Cylinder
55 Backhoe Bucket Cylinder (High Rotation) Extendable Stick
56 Backhoe Bucket Cylinder (High Rotation)
57 Stick Cylinder
58 Line Relief Valve for Head End of Stick Cylinder
59 Extendable Stick Cylinder (If Equipped)
Line Relief (If Equipped) for the Rod End of the
Extendable Stick Cylinder (If Equipped)
61 Extendable Stick/Auxiliary Control Valve (If Equipped)
62 Valve Cover
Check Valve (If Equipped) for the Rod End of the
Extendable Stick Cylinder (If Equipped)
Head End Relief Valve (If Equipped) for the
Extendable Stick Cylinder (If Equipped)
65 Stick Control Valve
Check Valve (If Equipped) for the Rod End of the
Stick Cylinder
67 Line Relief Valve for Head End of Boom Cylinder
68 Backhoe Bucket Control Valve
69 Line Relief Valve for Rod End of Bucket Cylinder
70 Backhoe Control Valve (Four Bank Valve) (If Equipped)
71 Backhoe Control Valve (Five Bank Valve) (If Equipped)
72 Backhoe Control Valve (Six Bank Valve) (If Equipped)
73 Swing Control Valve
74 Boom Control Valve
Check Valve (If Equipped) for the Rod End of the
Boom Cylinder
76 Line Relief Valve for Rod End of Stick Cylinder
77 Extendable Stick/Auxiliary Control Valve (If Equipped)
78 Pilot Valve for the Backhoe Joystick
79 Selector Valve (Joystick Pattern) (If Equipped)
80 Pilot Valve for the Backhoe Joystick
66
75
DESCRIPTION
60
63
64
Tap
Number
Description
AA PUMP PRESSURE TEST PORT
BB PUMP SIGNAL PRESSURE TEST PORT
CC PILOT PRESSURE TEST PORT
DD USED WITH PARALLEL LIFT LOADER
EE USED WITH ALL WHEEL STEER
FF USED WITH NON-ALL WHEEL STEER
GG USED WITH ALL WHEEL STEER
HH NOT USED WITH ALL WHEEL STEER
JJ WIRED TO THE CONTROLLER
Tap Locations
Pressure, Sampling, and Sensor
1
3
2
4
6
8
9
10
5
11
7
12
13
14
15 16
17
18
19
20
21
22 23
24
30
31
32
33 34
37
28
4243
29
39
46
45
41
44
40
38
25
26
35
36
27
48
51
52
55
56
57
78
80
79
4749
50
53
54
58
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
59
RENR3569-04 VOL 1
20 Page, Color 2
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
1
2
3
4
5
6
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
28
A
B
C
D
E F
G
H
AA
BB
CC
DD
GG
HH
JJ
EE
FF
E F
G
H
J
K
L
M
45
46
47
48
49
50
51
52
53
77 76
75
74
73
72
71 70
69
68
54
55 56
57
58
59
60
61
62
63
64
65
66
67
78
79
80
DRAIN / RETURN LINE
LINES GROUP COLOR DESCRIPTIONS
MAIN PUMP OUTPUT
LIFT CYLINDER CIRCUIT
STEERING CIRCUIT
TILT CYLINDER CIRCUIT
BOOM CYLINDER CIRCUIT
STABILIZER CIRCUIT (LEFT AND RIGHT)
LOAD SENSING (RESOLVER CIRCUIT)
SWING CYLINDER CIRCUIT
SUPPLY LINE
STICK CYLINDER CIRCUIT
AUX CONTROL VALVE (EXTENDABLE STICK) - (IF EQUIPPED)
EXTENDABLE STICK CYLINDER CIRCUIT (IF EQUIPPED)
BUCKET CYLINDER CIRCUIT (BACKHOE) (HIGH ROTATION)
BUCKET CYLINDER (MULTIPURPOSE) - (IF EQUIPPED)
COUPLER CYLINDER CIRCUIT
7
THIS SCHEMATIC IS FOR THE 420D, 430D, 432D and 442D BACKHOE LOADER.
Components are shown installed on a fully operable machine with the key and engine
off and transmission shifter in neutral.
RENR3569-04 VOL 2
20 Page
Volume 2
RENR3569-04
July 2005
420D and 430D Backhoe
Hydraulic System
©
2005 Caterpillar
All Rights Reserved
Printed in U.S.A.
420D:
BKC1-919
BMC1-1059
BLN1-UP
430D:
BNK1-UP
BML1-UP
432D:
BLD1-UP
442D:
BRG1-UP
BRY1-UP
Volume 1: Parallel Lift, Side Shift
420D:
BKC1-919
BMC1-1059
BLN1-UP
FDP1-UP
430D:
BNK1-UP
BML1-UP
Volume 2: Single Tilt, Center Pivot
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)
1
2
3
4
5
6 7 8 9 11
13
24 25 26
10
12
23
30
29
27
31 32
33 36
3435
42
58
37 38 39
41
45 46 50 52 53
54 55 56 57
59
60
61
62
63
64
65
66
67
68
69
47 48
51
49
44
43
71
70 72
40
17
21
20
13
1615
19
22
28
18
Item No. Component
ITEM DESCRIPTION
1 Rear Steering Cylinder (If Equipped)
A STABILIZER DOWN POSITION
2 All Wheel Steer Valve (If Equipped)
B STABILIZER UP POSITION
3 Steering Cylinder All Wheel Drive (If Equipped)
C STABILIZER DOWN POSITION
4 Steering Cylinder
D STABILIZER UP POSITION
5 Multipurpose Bucket Cylinder (If Equipped)
E BACKHOE BOOM DOWN POSITION
6 Auxiliary Relief Valve
F BACKHOE BOOM UP POSITION
7 Auxiliary Control Valve
G BACKHOE BOOM SWING LEFT POSITION
8 Line Relief Valve for Rod End of Tilt Cylinder
H BACKHOE BOOM SWING RIGHT POSITION
9 Line Relief Valve for Head End of Tilt Cylinder
J BACKHOE BUCKET DUMP POSITION
10 Tilt Cylinder
K BACKHOE BUCKET CLOSE POSITION
11 Loader Tilt Control Valve
L BACKHOE STICK OUT POSITION
12 Pressure Reducing Valve for the Tilt Control Valve
M BACKHOE STICK IN POSITION
13 Lift Cylinder Loader
14 Loader Lift Control Valve
15 Ride Control Solenoid Valve
16 Ride Control Accumulator
17 Steering Metering Pump
18 Back Pressure Check Valve (Return Oil)
19 Hydraulic Oil Filter
20 Hydraulic Oil Cooler
21 Hydraulic Tank
22 Piston Pump
23 Pressure Switch
24 Steering Priority Valve
25 Two Bank Valve for Loader
26 Three Bank Valve for Loader
27 Pilot Two Bank Control Valve
28 Return Manifold
29 Pilot Oil Accumulator
30 Solenoid Valve (Pilot Shutoff) for Hydraulic Lock Control
31 Pressure Reducing valve
32 Stabilizer Control Valve (Two Bank)
33 Stabilizer Control Valve
34 Stabilizer Cylinder
35 Stabilizer Cylinder
36 Stabilizer Control Valve
37 Shuttle Valve
38 Inlet Cover
39 Flow Control Valve (If Equipped)
40 Boom Cylinder
41 Line Relief Valve for Rod End of Boom Cylinder
42 Line Relief Valve for Rod End on Swing Cylinder
43 Swing Cylinder
44 Swing Cylinder
45 Crossover Relief Valve (If Equipped)
46 Line Relief Valve for Head End of Bucket Cylinder
47 Backhoe Bucket Cylinder (High Rotation) Extendable Stick
48 Backhoe Bucket Cylinder (High Rotation)
49 Stick Cylinder
50 Line Relief Valve for Head End of Stick Cylinder
51 Extendable Stick Cylinder (If Equipped)
Line Relief (If Equipped) for the Rod End of the
Extendable Stick Cylinder (If Equipped)
53 Extendable Stick/Auxiliary Control Valve (If Equipped)
54 Valve Cover
Check Valve (If Equipped) for the Rod End of the
Extendable Stick Cylinder (If Equipped)
Head End Relief Valve (If Equipped) for the
Extendable Stick Cylinder (If Equipped)
57 Stick Control Valve
Check Valve (If Equipped) for the Rod End of the
Stick Cylinder
59 Line Relief Valve for Rod End of Stick Cylinder
60 Backhoe Bucket Control Valve
61 Line Relief Valve for Rod End of Bucket Cylinder
62 Backhoe Control Valve (Four Bank Valve) (If Equipped)
63 Backhoe Control Valve (Five Bank Valve) (If Equipped)
64 Backhoe Control Valve (Six Bank Valve) (If Equipped)
65 Swing Control Valve
66 Boom Control Valve
Check Valve (If Equipped) for the Rod End of the
Boom Cylinder
68 Line Relief Valve for Head End of Boom Cylinder
69 Extendable Stick/Auxiliary Control Valve (If Equipped)
70 Pilot Valve for Backhoe Joystick
71 Selector Valve (Joystick Pattern) (If Equipped)
72 Pilot Valve for Backhoe Joystick
67
Description
PILOT CONTROLS
52
55
56
58
Tap
Number
Description
AA PUMP PRESSURE TEST PORT
BB PUMP SIGNAL PRESSURE TEST PORT
CC PILOT PRESSURE TEST PORT
DD USED WITH ALL WHEEL STEER
EE USED WITH NON-ALL WHEEL STEER
FF USED WITH ALL WHEEL STEER
GG NOT USED WITH ALL WHEEL STEER
Tap Locations
Pressure, Sampling, and Sensor
RENR3569-04 VOL 2
20 Page, Color 2
DRAIN / RETURN LINE
LINES GROUP COLOR DESCRIPTIONS
MAIN PUMP OUTPUT
LIFT CYLINDER CIRCUIT
STEERING CIRCUIT
TILT CYLINDER CIRCUIT
BOOM CYLINDER CIRCUIT
STABILIZER CIRCUIT (LEFT AND RIGHT)
LOAD SENSING (RESOLVER CIRCUIT)
SWING CYLINDER CIRCUIT
SUPPLY LINE
STICK CYLINDER CIRCUIT
AUX CONTROL VALVE (EXTENDABLE STICK) - (IF EQUIPPED)
EXTENDABLE STICK CYLINDER CIRCUIT (IF EQUIPPED)
BUCKET CYLINDER CIRCUIT (BACKHOE) (HIGH ROTATION)
BUCKET CYLINDER (MULTIPURPOSE) - (IF EQUIPPED)
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
THIS SCHEMATIC IS FOR THE 420D and 430D BACKHOE LOADER.
Components are shown installed on a fully operable machine with the key and engine
off and transmission shifter in neutral.
1
2
3 4
5
6
7
8
9
10
11
23
24
25
26
27
28
29
30
31
32
33
34
35
36
42
AA
BB
CC
EE
DD
FF
GG
A
B
C
D
E F
G
H
J
K
L
M
37
38
39
40
41
43
44
45
46
47 48
49
50
51
52
53
54
55
56
57
59
58
60
61
6263
64
65
66
69
68
67
70
71
72
12
13
14
15
16
17
18
19
20
21
22
