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Tap Table
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©
2010 Caterpillar, All Rights Reserved
Printed in U.S.A.
KENR7776
June 2010
374D Excavator
Hydraulic System
PJA1-UP
PAP1-UP
PAS1-UP
PAX1-UP
COMPONENT LOCATION
Description
Part
Number
Machine
Location
Schematic
Location
Accumulator Gp - Pilot 335-0546 1
D-4
Core As - Oil Cooler, Hydraulic Oil 245-9335 2 B-7
Filter Gp - Oil, Hydraulic Return 234-4531 3
A-8
Filter Gp - Oil, Hydraulic Return 242-6878 4
A-8
Filter Gp - Oil, Hydraulic, Case Drains 6E-5534 5 A-7
Filter Gp - Oil, Hydraulic, Pilot 185-0336 6 B-8
Manifold and Valve Gp - Load Sensing 310-0122 7
B-6
Motor Gp - Right Travel 228-3238 8
F-5
Motor Gp - Fan 311-9550 9
A-7
Motor Gp - Left Travel 228-3238 10 F-6
Motor Gp - Swing, LH 295-9414 11 F-4
Motor Gp - Swing, RH 295-9416 12
F-3
Pump Gp - Hydraulic Fan 247-8968 13 A-5
Pump Gp - Main Hydraulics 295-9676 14
A-3
Pump Gp - Pilot 155-9222 15
A-5
Pump Gp - Swing 295-9677 16
A-4
Sensor Gp - Press. Load Sense 221-8859 17 B-6
Sensor Gp - Press., Boom Raise 221-8859 18
B-4
Sensor Gp - Press., Main Hydr. Pump 260-2180 19 A-3
Sensor Gp - Press., Swing Pump Output 260-2180 20
B-4
Swivel Gp 295-9595 21
E-5
Tank As - Hydraulic Oil 227-0411 22 A-7
Valve Gp - Left Travel Counterbalance 143-8067 23 E-6
Valve Gp - Right Travel Counterbalance 143-8067 24 E-5
Valve Gp - Check 201-9381 25 C-8
Valve Gp - Check 201-9382 26 C-2
Valve Gp - Control, Swing (RH) 241-8928 27
E-3
Valve Gp - Main Control 323-7782 28
D-3
Valve Gp - Manifold and Reducing, Pilot 140-0736 29 D-5
Valve Gp - Solenoid, Hydr. Pump Control 352-6819 30 B-5
Valve Gp - Swing Cushion (LH) 315-4394 31
E-4
NOTE: Always refer to Part Manual for your specific Machine.
Always refer to Part Manual for your specific Cylinder Information
TAP LOCATION
Tap
Number
Description
Schematic
Location
FN Fan Pump Output Pressure A-5
M1 Swing Pump Stoking Pressure A-4
M1A Drive Pump Stoking Pressure A-3
M1B Idler Pump Stoking Pressure A-2
M2 Swing Pump Output Pressure B-5
MZA Drive Pump Power Swift Pressure A-3
MZB Idler Pump Power Swift Pressure A-2
PG Pilot Pressure D-4
SOS Hydraulic Oil Sampling A-5
XA Drive Pump Load Sense Pressure B-3
XB Idler Pump Load Sense Pressure B-2
FLUID POWER SYMBOLS
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
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 ACTINGSINGLE 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
ELECTRICAL SYMBOLS
Hydraulic Symbols (Electrical)
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
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
Electrical Symbols (Electrical)
T
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
PILOT PUMP OUTPUT
DRIVE PUMP OUTPUT
HIGH PRESSURE ON
COOLING FAN PUMP AND CIRCUIT
SUPPLY LINE
STICK CYLINDER CIRCUIT
LEFT TRAVEL MOTOR CIRCUIT
ATTACHMENT CIRCUIT
SWING MOTOR CIRCUIT
DRAIN / RETURN LINE
SWING BRAKES CIRCUIT
IDLER PUMP OUTPUT
TRAVEL SPEED CONTROL CIRCUIT
BUCKET CONTROL CIRCUIT
RIGHT TRAVEL MOTOR CONTROL CIRCUIT
BOOM CONTROL CIRCUIT
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
YY
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.
374D EXCAVATOR HYDRAULIC SYSTEM
PART NUMBER: 297-0213, CHANGE: 01, VERSION: HE
MEDIA NUMBER KENR7776
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
STICK CYLINDERBUCKET CYLINDER BOOM CYLINDER
TRAVEL MOTOR (RIGHT)TRAVEL MOTOR (LEFT)
SWING MOTOR (RIGHT)
SWING MOTOR (LEFT)
Pi5
Pi4
Pi3
Pi2
Pi1
PSA4
PSA3
PSA2
PSA1
PG
PAC
DR1
DR2
DR3
DR4
DR5
DR6
P-IN
T-OUT
Pi6
DR5
DR6
G
T2
T1
R
A
M2
A
S
DR1
DR
S
M1
L2
L1
XB
MZB
ZB
T1T2
M1B
S
M1A
T1T2
ZA
MZA
XA
M3
M2
GA
GB
PA
PB
MA
MB
MXA
MXB
BR3
AR3
PP3
T1
T2
BG
B
A
AG
BG AG
A
B
T2
T1
PP3
DB
PG
PB
PA
B
SDr2
P
T
SDr1
B
A
PA
PB
M
M
PG2
DB
PG1
BA
DR3
PS3
DR2
PS2
Pi1
Pi2
DR
DR1
A
PS4
DR4
R R
A1
B1
P. P.O
P. P.I
(FWD)
(FWD)
(BKWD)
(BKWD)
A1
B1
(R)
(L)
(R)
(L)
L1
G
Dr
L2
T
C1
C2
P
BR1 AR1AL1BL1BR2 AR2
PF PR
AL2 BL2 AL3 BL3
BR2 AR2
BR1 AR1
PF
PR
BL1AL1
AL2 BL2AL3 BL3
A
B
L
BR
L
BR
A
B
Qmax Qmin
Qmax QminQmax Qmin
(FWD)
(FWD)
(IN)
(BKWD)
(BKWD)
(OUT)
STICK
TRAVEL(L)
TRAVEL(R)
(CLOSE)
(UP)
(OPEN)
(DOWN)
BOOM
BUCKET
ATCH
HPC-OFF
aL3
aL2
aL1
bL3
bL2
(bL1)
R2
aR1
aR2
aR3
bR1
bR2
bR3
R1
HPC-ON
(EXT)
(RET)
SP
PR
PD
Dr
Dr
XA
XB
MZB
MZA
M1
M2
M1B
M1A
SOS
FN
PG
(1) ACCUMULATOR GP
PILOT
335-0546
(3) FILTER GP
OIL, HYDRAULIC RETURN
234-4531
(4) FILTER GP
OIL, HYDRAULIC
RETURN
242-6878
(5) FILTER GP
OIL, HYDRAULIC,
CASE DRAINS
6E-5534
(6) FILTER GP
OIL, HYDRAULIC, PILOT
185-0336
(7) MANIFOLD AND VALVE GP
LOAD SENSING
310-0122
(8) MOTOR GP
RIGHT TRAVEL
228-3238
(10) MOTOR GP
LEFT TRAVEL
228-3238
(9) MOTOR GP
FAN
311-9550
(11) MOTOR GP
SWING, LH
295-9414
(12) MOTOR GP
SWING, RH
295-9416
(13) PUMP GP
HYDRAULIC FAN
247-8968
(14) PUMP GP
MAIN HYDRAULICS
295-9676
(15) PUMP GP
PILOT
155-9222
(16) PUMP GP
SWING
295-9677
(17) SENSOR GP
PRESS. LOAD SENSE
221-8859
(18) SENSOR GP
PRESS., BOOM RAISE
221-8859
(19) SENSOR GP
PRESS., MAIN HYDR.
PUMP
260-2180
(20) SENSOR GP
PRESS., SWING PUMP OUTPUT
260-2180
(21) SWIVEL GP
295-9595
(23) VALVE GP
LEFT TRAVEL COUNTERBALANCE
143-8067
(24) VALVE GP
RIGHT TRAVEL
COUNTERBALANCE
143-8067
(25) VALVE GP
CHECK
201-9381
(26) VALVE GP
CHECK
201-9382
(27) VALVE GP
CONTROL,
SWING (RH)
241-8928
(31) VALVE GP
SWING CUSHION (LH)
315-4394
(28) VALVE GP
MAIN CONTROL
323-7782
(29) VALVE GP
MANIFOLD AND REDUCING, PILOT
140-0736
(30) VALVE GP
SOLENOID,
HYDR. PUMP CONTROL
352-6819
(2) CORE AS
OIL COOLER,
HYDRAULIC OIL
245-9335
(22) TANK AS
HYDRAULIC OIL
227-0411
(52) VALVE GP - CONTROL
138-1234
Callout Number
(Machine Location from
Component Locations Table
Component
Name
Part Number

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