KENR7658-01 October 2008
420E and 430E Bac k hoe Loader H y dr d r a u l i c Sy s t e m 420E:
430E:
PRA1-UP
SCD1-UP
PHC1-UP
RLN1-UP
©2008 Caterpillar, All Rights Reserved
Printed in U.S.A.
Component Table ITEM
NAME
PART NUMBER
1
PUMP GP.
267-2755
2
HYDRAULIC TANK
297-1233
3
TANK GROUP
297-1232
4
HYDRAULIC COOLER
304-7847
5
FILTER
226-9747
6
HMU
210-6240
STEER CYLINDER 7
FRONT
214-5097
LIFT CYLINDERS 8A
ST
228-3509
8B
PL/IT
228-3505
TILT CYLINDERS 9A
ST
200-7128
9B
PL/IT
192-3884
10
MP BUCKET CYL.(OPT)
185-1839
STABILIZER CYLINDERS 11A
LH
262-7049
11B
RH
262-7050 268-9050(S)
12
BOOM CYLINDER
13
STICK CYL.
210-7091(S)
14
SWING CYL.
278-1971
15
BUCKET CYL.
210-7095(S)
16
E-STICK CYL (OPT).
210-7097(S)
210-7076
VALVE PILOT 2-BANK 17A
VALVE PILOT-BODY
223-4713
17B
LEVER W/DTNT & SWTCH (OPT)
223-4715
18
ACCUMULATOR
226-0420
19
RIDE CNTRL VALVE (OPT)
245-8780
20
RIDE CNTRL ACCMLTR (OPT)
162-3960
21
RIDE CNTR PRES. SWTCH(OPT)
304-5696
22
TEMP. SENSOR (OPT)
23
DIFF. PRES. SWITCH (OPT)
134-0404
25
COUPLER VALVE (Volume 2)
231-2615
26
COUPLER CYLINDER (Volume 2)
190-3085
N/A
LOADER VAL VE (ST) 27
2 BANK
266-2552
27
3 BANK
266-2553
27A
INLET SECTION
269-1080
27B
LIFT SECTION
269-1091
27C
TILT SECTION
269-1092
27D
AUX SECTION
269-1093
27E
OUTLET MANIFOLD
269-1079
LOADER VALVE (PL/IT) 28
3 BANK
266-2563
28B
LIFT SECTION
269-1081
28C
TILT SECTION
269-1082
28D
AUX SECTION
269-1083
SCHEMATIC
LOCATION
Component Table Continued ITEM
NAME
PART NUMBER BACKHOE VALVE (CP)
29
6 BANK
266-2556
29
7 BANK
266-2557
29
8 BANK
266-2558
29A
BOOM SECTION
269-1062
29B
SWING SECTION
269-1064
29C
BUCKET SECTION
269-1065
29D
STICK SECTION
269-1063
29G
E-STICK SECTION
269-1066
29H
RH STABILIZER SECTION
269-1061
29E
AUX SECTION
269-1067
29F
OUTLET MANIFOLD
269-1059
29J
INLET MANIFOLD
269-1060
29K
PATTERN SWITCHING VALVE
257-7724
29L
LH STABILIZER SECTION
269-1061
SCHEMATIC
BA CKHOE VALVES (COMMON) 30
VALVE GP - CUSHION RELIEF
206-3685 (STD)
31
VALVE GP - PILOT (BACKHOE)
267-2758
32
VALVE GP - PILOT (LOADER)
267-2758
33
MANIFOLD - PILOT
268-0094
LOCATION
Pressure Tap Table
TAP LOCATIONS Tap
Description
T1
Pump Discharge
T2
Load Sense
T3
Pilot Pressure
SOS
Oil Sampling
Schematic
Location
FLUID POWER SYMBOLS BASIC COMPONENT SYMBOLS
MAIN AUX.
PUMP or MOTOR
SPRING (ADJUSTABLE)
VARIABILITY
CONTROL VALVES
SPRING
FLUID CONDITIONER
PRESSURE COMPENSATION
LINE RESTRICTION (VARIABLE)
TWO POSITION
HYDRAULIC PNEUMATIC ENERGY TRIANGLES
THREE POSITION
PUMP: VARIABLE and PRESSURE COMPENSATED
2-SECTION PUMP
ATTACHMENT
LINE RESTRICTION VARIABLE and PRESSURE COMPENSATED
VALVES
VALVE ENVELOPES
ONE POSITION
LINE RESTRICTION (FIXED)
RESTRICTION
VALVE PORTS
TWO-WAY
FOUR-WAY
THREE-WAY
CONTROL VALVES
CHECK VALVES
AB
AB
P T SHIFTED POSITION
P T NORMAL POSITION
INFINITE POSITION
SHUTTLE
SPRING LOADED
BASIC SYMBOL
PILOT CONTROLLED
FLUID STORAGE RESERVOIRS
VENTED
RETURN ABOVE FLUID LEVEL
PRESSURIZED
RETURN BELOW FLUID LEVEL
MEASUREMENT
PRESSURE
TEMPERATURE
ROTATING SHAF TS
FLOW
UNIDIRECTIONAL
BIDIRECTIONAL
COMBINATION CONTROLS
SOLENOID
SOLENOID or MANUAL
SERVO
SOLENOID and PILOT or MANUAL
SOLENOID and PILOT
DETENT
THERMAL
MANUAL CONTROL SY MBOLS
PUSH-PULL LEVER
MANUAL SHUTOFF
RELEASED PRESSURE
EXTERNAL RETURN
PUSH BUTTON
PILOT CONTROL SYMBOLS
INTERNAL RETURN
ACCUMULATORS
SPRING LOADED
GAS CHARGED
HYDRAULIC PUMPS FIXED DISPLACEMENT
GENERAL MANUAL
VARIABLE DISPLACEMENT NON-COMPENSATED
PEDAL
REMOTE SUPPLY PRESSURE
SIMPLIFIED
CROSSING AND J OINING LINES
LINES CROSSING
LINES JOINING
VARIABLE DISPLACEMENT NON-COMPENSATED
UNIDIRECTIONAL
UNIDIRECTIONAL
BIDIRECTIONAL
BIDIRECTIONAL
INTERNAL SUPPLY PRESSURE
COMPLETE
HYDRAULIC AND PNEUMATIC CYLINDERS
SINGLE ACTING
HYDRAULIC MOTORS FIXED DISPLACEMENT
SPRING
DOUBLE ACTING
INTERNAL PASSAGEWAYS
INFINITE POSITIONING
FLOW IN ONE DIRECTION
THREE POSITION
PARALLEL FLOW
CROSS FLOW
TWO POSITION
FLOW ALLOWED IN EITHER DIRECTION
ELECTRICAL SYMBOLS Hydraulic Symbols (Electrical)
M
G Transducer (Fluid)
Transducer (Gas / Air)
Pressure Switch (Adjustable)
Pressure Switch
Generator
Electric Motor
Electrical Wire
Temperature Switch
Electrical Symbols (Electrical)
T
Pressure Symbol
Temperature Symbol
Level Symbol
Flow Symbol
Wire Number Identification Codes
Electrical Schematic Example
Current Standard
Current Standard Harness identification code This example indicates wire 135 in harness "AG".
Hydraulic Schematic Example
Wire Circuit Number Identification
Wire Color
325-AG135 PK-14 325-PK Circuit Identification Number
Wire Color
Wire Gauge
Previous Standard Wire Color
Wire
325-PK-14 B Circuit Number Identification
A
Wire Gauge (EXAMPLE VALVE)
8
7
6
5
4
11B
2
1
BOOSTED BRAKES (REF)
14 12
3
15
13
16
33
11A
TO REAR AXLE LEFTWHEEL BRAKE
F
F LEFT BRAKE PEDAL
29
TO REAR AXLE
29D
RIGHTWHEELBRAKE
BACKHOE VALVE RIGHT BRAKE PEDAL
BS
BT
18
E
E
STAB RH
29J
B OOM
29H
STICK
SWING
29A
BUCK ET
29B
E-STICK
AUX.
29G
29C
STA B LH
29E
29L
29F
29K
D
D
20 STABILIZER JOYSTICK
21
LEFT JOYSTICK
RIGHT JOYSTICK
19
27A
T3
17C17A
31
31
C
C
27B DEL
LIFT
8A
9A
T2 33
1
27C TILT
22 SOS
B
5
T1
27D
IMPLEMENTandSTEERING PUMP CIRCUIT PILOT OILCIRCUIT BOOSTEDBRAKE OILCIRCUIT LOADSENSE CIRCUIT
23
SUPPLY LINE DRAIN / RETURNLINE STEERING CYLINDER CIRCUIT LIFTCY LINDER CIRCUIT TILTCYLINDER CIRCUIT
AUX
10
LOADER VALVE
PUMP
27E
27
AUXILIARY CIRCUIT(LOADER VALVE) STABILIZER CY LINDER CIRCUIT BOOMCYLINDER CIRCUIT STICK CYLINDER CIRCUIT SWING CYLINDER CIRCUIT BUCKETCYLINDER CIRCUIT E-STICK CYLINDER CIRCUIT AUXILIARY CIRCUIT(BACKHOE VALVE)
4
6
B
HYDRAULIC CIRCUITCOLOR DESCRIPTIONS
LINE PATTERNS PressureLine Pilot/ LoadSensingPressure
3
Drain / Retu rnLines ComponentGroup
2
A
A
Attachment
HMU
AirLine
CALLOUTS
7
FRONT STEER CYL.
Taps(Pressure,
YY
TANK
Sampling,Sensor)by letter
Components bynumber
52
THIS SCHEMATIC IS FOR THE 420E BACKHOE LOADER VOLUME 1 of 2
(ST)
PART NUMBER: 297-5426, CHANGE: 01, VERSION: -
Components areshowninstalledon a fullyoperablemachine. Referto theappropriateServiceManualfor Troubleshooting,Specifications andSystemsOperations.
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
BOOSTED BRAKES (REF)
14 11B
12
15
33
13
16
TO REAR AXLE LEFTWHEEL BRAKE
11A
F
F
LEFTBRAKE PEDAL
TO REAR AXLE RIGHTWHEEL BRAKE
29
29D
BACKHOE VALVE
RIGHTBRAKE PEDAL
BS
BT
18
E
E
STAB RH
29J
29H
B OOM
STICK
SWING
29A
BUCK ET
29B
E-STICK
29C
AUX.
29G
STA B LH
29E
29L
29F
29K
D
D
20 STABILIZER JOYSTICK
21
LEFT JOYSTICK
RIGHT JOYSTICK
19
27A
T3
31
31
17C17B 17A C
C
DEL
LIFT
8B
28B
LOADER JOYSTICK
9B
32 33
FLOAT
T2
RTD
1
TILT
B
28C
22
10
HYDRAULICCIRCUITCOLOR DESCRIPTIONS
SOS
5
T1
23 AUX
28B
IMPLEMENTandSTEERING PUMP CIRCUIT PILOTOILCIRCUIT BOOSTEDBRAKE OILCIRCUIT LOADSENSE CIRCUIT SUPPLY LINE DRAIN / RETURNLINE STEERING CYLINDER CIRCUIT LIFT CYLINDER CIRCUIT TILTCYLINDER CIRCUIT AUXILIARY CIRCUIT(LOADER VALVE) STABILIZER CYLINDER CIRCUIT
B
8
7
6
5
4
3
2
1
BOOSTED BRAKES (REF)
14 11B
12
15
33
13
16
TO REAR AXLE LEFTWHEEL BRAKE
11A
F
F
LEFTBRAKE PEDAL
TO REAR AXLE RIGHTWHEEL BRAKE
29
29D
RIGHTBRAKE PEDAL
BACKHOE VALVE
BS
BT
18
E
E
STAB RH
29J
29H
B OOM
STICK
SWING
29A
BUCK ET
29B
E-STICK
AUX.
29G
29C
STA B LH
29E
29L
29F
29K
D
D
20 STABILIZER JOYSTICK
21
LEFT JOYSTICK
RIGHT JOYSTICK
19
27A
T3
31
31
17C17B 17A C
C
DEL
LIFT
8B
28B
LOADER JOYSTICK
9B
32 33
T2
RTD
FLOAT
1
TILT
B
28C
22
10
IMPLEMENTandSTEERING PUMP CIRCUIT PILOTOILCIRCUIT BOOSTEDBRAKE OILCIRCUIT LOADSENSE CIRCUIT SUPPLY LINE DRAIN / RETURNLINE STEERING CYLINDER CIRCUIT LIFT CYLINDER CIRCUIT TILTCYLINDER CIRCUIT AUXILIARY CIRCUIT(LOADER VALVE) STABILIZER CYLINDER CIRCUIT BOOMCYLINDER CIRCUIT STICK CYLINDER CIRCUIT SWING CYLINDER CIRCUIT BUCKETCYLINDER CIRCUIT E-STICK CYLINDER CIRCUIT AUXILIARY CIRCUIT(BACKHOE VALVE)
5 23
AUX
28B LOADER VALVE
4
6
PUMP
27E
28
B
HYDRAULICCIRCUITCOLOR DESCRIPTIONS
SOS
T1
LINE PATTERNS PressureLine
26
25
Pilot/ LoadSensingPressure Drain / Retu rnLines
3
ComponentGroup
A
A
Attachment
2
AirLine
HMU
CALLOUTS Taps(Pressure,
YY
FRONT STEER CYL.
TANK
7
Sampling,Sensor)by letter
Components bynumber
52
THIS SCHEMATIC IS FOR THE 420E BACKHOE LOADER VOLUME 2 of 2
( PL / IT )
PART NUMBER: 297-5426, CHANGE: 01, VERSION: -
Components areshowninstalledon a fullyoperable machine. Referto theappropriateServiceManualfor Troubleshooting, Specifications andSystemsOperations.
8
7
6
5
4
3
2
1
Hydraulic Components - Chassis View
13
12
30
29
11A
31
33
5
6
3
2
8
4
9
10
26 25
16 15
14
14
11B
17
32
18
28
1
19
20
8
7
9
10
Hydraulic Components - Chassis View
13
12
30
29
11A
31
33
5
6
3
2
8
4
9
10
26 25
16 15
14
14
11B
17
32
18
1
28
19
20
7
8
9
10
Backhoe Valve (8 Bank) For other bank valve configurations see RENR6487 (Specifications Manual).
29F
29L
29C
29G
29C 29B
29D
29A
29H J
L
Backhoe Valve (8 Bank) For other bank valve configurations see RENR6487 (Specifications Manual).
29F
29L
29C
29G
29C 29B
29D
29A
29H J
L
M
29J
EIGHT BANK VALVE (PILOT OPERATED)
(29F) Outlet Manifold (29L) Left Stabilizer Control Valve (29E) Auxiliary Control Valve (29G) Extendable Stick Control Valve (29C) Bucket Control Valve (29B) Swing Control Valve (29D) Stick Control Valve
(29A) Boom Control Valve (29H) Right Stabilizer Control Valve ( J ) Pilot On/Off Solenoid Valve (29J ) Inlet Manifold (L) A Ports (M) B Ports
Implement and Steering Pump B
1
A
T2
27
D
C
T1
E G C
T2
H A
T2 B Drain
T1 E D
C
F
These illustrations show the implement and steering pump (1) out of the machine. The following components are visible: Torque control adjustment (A), Flow compensator adjustment (B), Load sensing pressure tap ( T2), Inlet port (C), Case drain port (D), Torque control solenoid (E), Discharge pressure tap ( T1), Torque limiter (F), Outlet port (G), Loader Valve (27). The implement and steering pump on the 420E/430E machines are similar to the "D" Series machines, but now includes a torque control solenoid (not visible). The torque control solenoid provides an additional pump setting. The implement and steering pump is located below the floor plate in the cab. The pump control valve (H) contains a torque control spool adjustment screw (B) and a flow compensator adjustment screw (A). The adjustment screws and the load sensing pressure tap ( T2) are accessible from the cab.
Hydraulic Oil Filter Temp Sensor
SOS
Filter Bypass Switch
Temp Sensor
Filter Bypass Switch
SOS
The hydraulic oil filter is located below the machine at the left frame rail. The hydraulic oil filter bypass switch is mounted to the oil filter base.
Loader Valve
SOS
1 5 Three Bank (Mechanically Controlled)
27B 27C 27D 27A
27 28C H
J
28B
L
K
27A
G
The loader valve is accessed from below the floor plate. The loader control valve group contains: (27E) Outlet manifold
28D
(27D, 28D) Auxiliary control valve (27C, 28C ) Tilt control valve (27B, 28B ) Lift control valve
27E
28
(27A) Inlet manifold (F) Load sensing relief valve (G) Solenoid for the B circuit (H) Solenoid for the A circuit ( J ) Makeup and relief valve (K ) B pilot line port
P
(L ) A pilot line port (M) Priority Valve
R
(N) Dead engine lower valve (P ) A ports
N
M
F
(R ) B ports
THREE BANK VALVE (PILOT OPE RATED)
NOTE:
Machines with a mechanically controlled loader valve or a pilot controlled loader valve use the same inlet manifold.
For other bank valve configurations see RENR6487 (Specifications Manual).
Ride Control (Option) Ride Control Solenoids
Ride Control Relay
21
19
20
ECM
Travel at high speeds over rough terrain causes bucket movement. The optional Ride Control System acts as a shock absorber by absorbing bucket forces, which stabilize the machine. The Ride Control Systemcomponents include; Ride Control Valve (19), Ride Control Relay, Ride Control Solenoids, Ride Control Accumulator (20), and Ride Control Pressure Switch (21). Two solenoids are now used on the "E" Series machines Ride Control System. The Ride Control System, on machines with the optional autoshift transmission, is controlled by the Machine ECM. The Machine ECM monitors the position of the ride control switch and determines when to operate the ride control system.
Boosted Brakes
To Wheel Brake
Slave Cylinder
To Tank
From Pilot Accumulator
Master Cylinder
Boost Brake Valve
This illustration shows a sectional view of the boosted brake valve group. When the brake pedal is depressed, the boost brake valve moves to the left and inlet oil from the pilot manifold is directed to the master cylinder.
A
E
D
C
B
The 420E/430E machines are equipped with hydraulically assisted master cylinders. The brake boost valves are connected to the master cylinder (A) at each brake pedal (B). Oil enters the master cylinder through the supply hose (C) and exits the master cylinder through the return hose (D). The oil flows to the service brakes through the hoses (E) at the bottom of the master cylinder. The master cylinders can be removed from the machine from inside the operator's compartment.
