RENR3569-02 FLUID POWER SYMBOLS

January 2004 BASIC COMPONENT SYMBOLS

DESCRIPTION
Item No. Component MAIN AUX.
PUMP: VARIABLE and
PUMP or MOTOR FLUID CONDITIONER SPRING CONTROL VALVES RESTRICTION LINE RESTRICTION 2-SECTION PUMP PRESSURE COMPENSATED
1 Rear Steering Cylinder (If Equipped) (FIXED)

2 All Wheel Steering Valve (If Equipped)

3 Steering Cylinder All Wheel Drive (If Equipped)
VARIABLILTY SPRING LINE RESTRICTION PRESSURE HYDRAULIC PNEUMATIC LINE RESTRICTION
4 Steering Cylinder (ADJUSTABLE) (VARIABLE) COMPENSATION ENERGY TRIANGLES (VARIABLE and PRESSURE COMPENSATED)

5 Multipurpose Bucket Cylinder (If Equipped) VALVES

6 Broom Motor (If Equipped) VALVE ENVELOPES VALVE PORTS

7 Auxiliary Control Valve

8 Coupler Cylinder
ONE POSITION TWO POSITION THREE POSITION TWO-WAY THREE-WAY FOUR-WAY
9 Coupler Valve
10 Diverter Valve CONTROL VALVES CHECK VALVES
11 Tilt Cylinder AB AB

12 Line Relief Valve for Rod End of Tilt Cylinder

P T P T
13 Inlet Cover
NORMAL POSITION SHIFTED POSITION INFINITE POSITION BASIC SYMBOL SPRING LOADED
14 Auxiliary Relief Valve
15 Line Relief Valve for Head End of Tilt Cylinder MEASUREMENT ROTATING SHAFTS
16 Steering Priority Valve
17 Two Bank Valve for Loader
18 Three Bank Valve for Loader PRESSURE TEMPERATURE FLOW UNIDIRECTIONAL BIDIRECTIONAL

19 Loader Lift Control Valve

FLUID STORAGE RESERVOIRS
20 Loader Tilt Control Valve
21 Lift Cylinder Loader
22
23
Ride Control Solenoid Valve
Pressure Switch
420D, 430D, 432D, and 442D VENTED PRESSURIZED RETURN ABOVE FLUID LEVEL RETURN BELOW FLUID LEVEL

24
25
Ride Control Accumulator
Steering Metering Pump
Parallel Lift Loader COMBINATION CONTROLS

26
27
All Wheel Steer Pressure Switch
Back Pressure Check Valve (Return Oil)
Hydraulic System SOLENOID SOLENOID SOLENOID SOLENOID and SERVO THERMAL DETENT
or MANUAL and PILOT PILOT or MANUAL
28 Hydraulic Oil Filter
29 Hydraulic Oil Cooler 420D: 430D: 432D: 442D: MANUAL CONTROL SYMBOLS
30 Hydraulic Tank BKC1-919 BNK1-UP BLD1-UP BRG1-UP
31 Piston Pump
32 Orifice Connector
BMC1-1059 BML1-UP BRY1-UP PUSH-PULL LEVER GENERAL MANUAL PUSH BUTTON PEDAL SPRING

33 Pilot Valve (Hydraulic Hand Control for the Loader) BLN1-UP PILOT CONTROL SYMBOLS
34 Orifice Connector RELEASED PRESSURE REMOTE SUPPLY PRESSURE
FDP1-UP
35 Return Manifold
36 Solenoid Valve (Pilot Shutoff) for Hydraulic Lock Control
37 Stabilizer Control Valve (Two Bank) EXTERNAL RETURN INTERNAL RETURN SIMPLIFIED COMPLETE INTERNAL
SUPPLY PRESSURE
38 Pressure Reducing Valve
39 Pilot Two Bank Control Valve ACCUMULATORS CROSSING AND JOINING LINES HYDRAULIC AND PNEUMATIC CYLINDERS
40 Pilot Oil Accumulator
41 Stabilizer Control Valve SPRING LOADED GAS CHARGED LINES CROSSING LINES JOINING SINGLE ACTING DOUBLE ACTING
42 Stabilizer Cylinder
43 Stabilizer Cylinder HYDRAULIC PUMPS HYDRAULIC MOTORS INTERNAL PASSAGEWAYS
44 Stabilizer Control Valve
FIXED VARIABLE DISPLACEMENT FIXED VARIABLE DISPLACEMENT THREE TWO
INFINITE
45 Shuttle Valve DISPLACEMENT NON-COMPENSATED DISPLACEMENT NON-COMPENSATED POSITIONING POSITION POSITION
46 Inlet Cover
UNIDIRECTIONAL UNIDIRECTIONAL
47 Flow Control Valve (If Equipped)
48 Boom Cylinder BIDIRECTIONAL BIDIRECTIONAL
FLOW IN ONE PARALLEL CROSS
FLOW
FLOW ALLOWED IN
DIRECTION FLOW EITHER DIRECTION
49 Line Relief Valve for Rod End of Boom Cylinder
50 Line Relief Valve for Rod End on Swing Cylinder
51 Swing Cylinder
Volume 1: With Center Pivot or Side Shift Backhoe
52 Swing Cylinder
53 Crossover Relief Valve (If Equipped) © 2004 Caterpillar Printed in U.S.A.
54 Line Relief Valve for Head End of Bucket Cylinder All Rights Reserved
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
60
Extendable Stick Cylinder (If Equipped)
61 Extendable Stick/Auxiliary Control Valve (If Equipped)
62 Valve Cover

63
Check Valve (If Equipped) for the Rod End of the 57 25
Extendable Stick Cylinder (If Equipped) 32 33 34 30
Head End Relief Valve (If Equipped) for the
64
Extendable Stick Cylinder (If Equipped) 55 56
65 Stick Control Valve
Check Valve (If Equipped) for the Rod End of the
66
Stick Cylinder

RENR3569-02 VOL 1
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 11 29
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 59
Check Valve (If Equipped) for the Rod End of the
75
Boom Cylinder

16 Page, B/W, TRM

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

48

Tap Locations 39
Pressure, Sampling, and Sensor
Tap
Description
Number
AA PUMP PRESSURE TEST PORT 50 49 47 46 45
BB PUMP SIGNAL PRESSURE TEST PORT
CC PILOT PRESSURE TEST PORT
61 60 58 54 53
DD USED WITH PARALLEL LIFT LOADER
66 65 64 63 62
EE USED WITH ALL WHEEL STEER 43 42 40 37 38 79 80 78 22 23 24 21 27 3 4 5 6 8 9 10
FF USED WITH NON-ALL WHEEL STEER 71 70 69 68 67
GG USED WITH ALL WHEEL STEER 41 44
HH NOT USED WITH ALL WHEEL STEER 76 75 74 73 72 31 28
JJ WIRED TO THE CONTROLLER 77
51 52 36 35 26 1 2 7 12
13 14
15 16 17
18 19 20
 43

44
42
7
39 41
6
2 3 4 5 13
1
8
40

14
9 CC
A B C D

10

35
GG
HH
12
11

15

36 37 38
DD
27
22
EE FF
21
20
25 24

51 52 53 55 56
28
26 45 46 57
59 60 61 62
19 48 49
50
47
54 58
23

16 17 18

29
RENR3569-02 VOL 1

30 31 BB 32
34
75 74 73 68 67 66 65 64 63
77 76 72 71 70 69

JJ
16 Page, B/W, TRM

80
AA E F G H

33
78
E F G H 79
J K L M

LINEAR PATTERNS
Pressure Line

Pilot/Load Sensing Pressure

Drain / Return Lines

Components

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.
 FLUID POWER SYMBOLS
RENR3569-02
BASIC COMPONENT SYMBOLS
Description January 2004
Item No. Component
MAIN AUX.
PUMP: VARIABLE and
1 Rear Steering Cylinder (If Equipped) PUMP or MOTOR FLUID CONDITIONER SPRING CONTROL VALVES RESTRICTION LINE RESTRICTION 2-SECTION PUMP PRESSURE COMPENSATED
(FIXED)
2 All Wheel Steer Valve (If Equipped)
3 Steering Cylinder All Wheel Drive (If Equipped)
4 Steering Cylinder SPRING LINE RESTRICTION PRESSURE HYDRAULIC PNEUMATIC LINE RESTRICTION
VARIABLILTY
COMPENSATION ENERGY TRIANGLES (VARIABLE and PRESSURE COMPENSATED)
5 Multipurpose Bucket Cylinder (If Equipped) (ADJUSTABLE) (VARIABLE)

6 Auxiliary Relief Valve VALVES

VALVE ENVELOPES VALVE PORTS
7 Auxiliary Control Valve
8 Line Relief Valve for Rod End of Tilt Cylinder
9 Line Relief Valve for Head End of Tilt Cylinder ONE POSITION TWO POSITION THREE POSITION TWO-WAY THREE-WAY FOUR-WAY
10 Tilt Cylinder
11 Loader Tilt Control Valve CONTROL VALVES CHECK VALVES
AB AB
12 Pressure Reducing Valve for the Tilt Control Valve
13 Lift Cylinder Loader
P T P T
14 Loader Lift Control Valve NORMAL POSITION SHIFTED POSITION INFINITE POSITION BASIC SYMBOL SPRING LOADED
15 Ride Control Solenoid Valve
MEASUREMENT ROTATING SHAFTS
16 Ride Control Accumulator
17 Steering Metering Pump
18 Back Pressure Check Valve (Return Oil)
PRESSURE TEMPERATURE FLOW UNIDIRECTIONAL BIDIRECTIONAL
19 Hydraulic Oil Filter
20 Hydraulic Oil Cooler FLUID STORAGE RESERVOIRS
21 Hydraulic Tank
22 Piston Pump
23
24
Pressure Switch
Steering Priority Valve
420D and 430D Single Tilt Loader VENTED PRESSURIZED RETURN ABOVE FLUID LEVEL RETURN BELOW FLUID LEVEL

25
26
Two Bank Valve for Loader
Three Bank Valve for Loader
Hydraulic System COMBINATION CONTROLS

27 Pilot Two Bank Control Valve

28 Return Manifold 420D: 430D: SOLENOID SOLENOID SOLENOID SOLENOID and SERVO THERMAL DETENT
or MANUAL and PILOT PILOT or MANUAL
29 Pilot Oil Accumulator BKC1-919 BNK1-UP MANUAL CONTROL SYMBOLS
30 Solenoid Valve (Pilot Shutoff) for Hydraulic Lock Control
31 Pressure Reducing valve BMC1-1059 BML1-UP
32 Stabilizer Control Valve (Two Bank) BLN1-UP PUSH-PULL LEVER GENERAL MANUAL PUSH BUTTON PEDAL SPRING
33 Stabilizer Control Valve
34 Stabilizer Cylinder
FDP1-UP PILOT CONTROL SYMBOLS
RELEASED PRESSURE REMOTE SUPPLY PRESSURE
35 Stabilizer Cylinder
36 Stabilizer Control Valve
37 Shuttle Valve
EXTERNAL RETURN INTERNAL RETURN SIMPLIFIED COMPLETE INTERNAL
38 Inlet Cover SUPPLY PRESSURE
39 Flow Control Valve (If Equipped)
ACCUMULATORS CROSSING AND JOINING LINES HYDRAULIC AND PNEUMATIC CYLINDERS
40 Boom Cylinder
41 Line Relief Valve for Rod End of Boom Cylinder
42 Line Relief Valve for Rod End on Swing Cylinder SPRING LOADED GAS CHARGED LINES CROSSING LINES JOINING SINGLE ACTING DOUBLE ACTING

43 Swing Cylinder
HYDRAULIC PUMPS HYDRAULIC MOTORS INTERNAL PASSAGEWAYS
44 Swing Cylinder
45 Crossover Relief Valve (If Equipped) FIXED VARIABLE DISPLACEMENT FIXED VARIABLE DISPLACEMENT INFINITE THREE TWO
46 Line Relief Valve for Head End of Bucket Cylinder DISPLACEMENT NON-COMPENSATED DISPLACEMENT NON-COMPENSATED POSITIONING POSITION POSITION
47 Backhoe Bucket Cylinder (High Rotation) Extendable Stick UNIDIRECTIONAL UNIDIRECTIONAL
48 Backhoe Bucket Cylinder (High Rotation)
FLOW IN ONE PARALLEL CROSS FLOW ALLOWED IN
49 Stick Cylinder BIDIRECTIONAL BIDIRECTIONAL DIRECTION FLOW FLOW EITHER DIRECTION

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
52 Volume 2: With Center Pivot Backhoe.
Extendable Stick Cylinder (If Equipped)
53 Extendable Stick/Auxiliary Control Valve (If Equipped) © 2004 Caterpillar Printed in U.S.A.
54 Valve Cover All Rights Reserved
Check Valve (If Equipped) for the Rod End of the
55
Extendable Stick Cylinder (If Equipped)
Head End Relief Valve (If Equipped) for the
56
Extendable Stick Cylinder (If Equipped)
57 Stick Control Valve
Check Valve (If Equipped) for the Rod End of the
58
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) 47 48 49
17
65 Swing Control Valve
66 Boom Control Valve
Check Valve (If Equipped) for the Rod End of the
67

RENR3569-02 VOL 2
Boom Cylinder 21
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) 10
72 Pilot Valve for Backhoe Joystick

51 20

16 Page, B/W, TRM

PILOT CONTROLS
ITEM DESCRIPTION
A STABILIZER DOWN POSITION
B STABILIZER UP POSITION
C STABILIZER DOWN POSITION
D STABILIZER UP POSITION
E BACKHOE BOOM DOWN POSITION
F BACKHOE BOOM UP POSITION
G BACKHOE BOOM SWING LEFT POSITION
H BACKHOE BOOM SWING RIGHT POSITION
J BACKHOE BUCKET DUMP POSITION
K BACKHOE BUCKET CLOSE POSITION
L BACKHOE STICK OUT POSITION
M BACKHOE STICK IN POSITION

40

Tap Locations
Pressure, Sampling, and Sensor
37 38 39 41 42
Tap
Description 44 43
Number
45 46 50 52 53
AA PUMP PRESSURE TEST PORT 71 70 72 15 16 23
BB PUMP SIGNAL PRESSURE TEST PORT 54 55 56 57 58
CC PILOT PRESSURE TEST PORT
59 60 61 62 63 35 34 31 32 3
DD USED WITH ALL WHEEL STEER 19 22 12 13 18 4 5
EE USED WITH NON-ALL WHEEL STEER
64 65 66 67 68 33 36
FF USED WITH ALL WHEEL STEER
GG NOT USED WITH ALL WHEEL STEER
69 27 29 30 28 1 2 6 7 8 9 11
13 24 25 26
 36

33 35
34
6 27
5
29
1 2 3 4

7 CC

A B C D
8
10
FF
28
GG

9
11

13
30
12
15
EE
DD
18 17 16 32 31

43 44 45 47 48

37 38 49
19 40 51 52 53 54
41
14 42
39
46 50

23
RENR3569-02 VOL 2

22 24 25 26
67 66 65 60 59 58 56 55
69 68 64 63 62 61 57
20 21 BB

72
16 Page, B/W, TRM

AA

70
E F G H 71
J K L M

LINEAR PATTERNS
Pressure Line
Pilot/Load Sensing Pressure
Drain / Return Lines
Components

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.