RENR7336-00
30 Page, DGM
©
2005 Caterpillar
All Rights Reserved
Printed in U.S.A.
RENR7336
February 2005
345C Excavator
Hydraulic System
SRY1-UP
GPH1-UP
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
AB
PT
AB
PT
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)
Description
Part
Number
Machine
Location
Schematic
Location
Accumulator Gp - Pilot Manifold 164-6981 B-6 29
Cooler Gp - Oil 210-8164 B-8 22
Cylinder Gp - Boom Note A E-1 9
Cylinder Gp - Bucket Note A E-2 8
Cylinder Gp - Stick Note A E-8 7
Filter Gp - Return (Inside Hydraulic Tank) 173-3434 A-5 and A-6 42
Filter Gp - Drain Return 126-2075 A-4 and A-6 41 and 44
Filter Gp - Pilot 158-8987 A-4 39
Motor Gp - Cooling Fan 242-6904 A-6 23
Motor Gp - Left Swing 225-4506 F-7 1
Motor Gp - Left Travel 232-6180 F-5 3
Motor Gp - Right Swing 225-4506 F-6 2
Motor Gp - Right Travel 232-6180 F-4 4
Pump Gp - Cooling 259-0814 B-1 32
Pump Gp - Drive / Idler / Pilot 259-0818 A-3 33
Sensor Gp - Drive Pump Pressure 221-8869 B-2 36
Sensor Gp - Idler Pump Pressure 221-8869 A-2 38
Switch As - Implement Pressure 106-1079 D-3 13
Switch As - Travel Pressure 106-1079 D-3 14
Swivel Gp - Joint 225-4547 E-5 10
Tank Gp - Hydraulic 227-0431 A-6 43
Valve Gp - Boom / Swing Priority 232-4102 B-4 31
Valve Gp - Check Boom / Stick 2 239-8902 D-1 12
Valve Gp - Check Boom 2 239-8906 D-6 12
Valve Gp - Check Cooler Bypass 123-2505 B-8 21
Valve Gp - Check Slow Return 185-0384 B-8 20
Valve Gp - Check Stick 239-8904 D-5 12
Valve Gp - Left Swing Motor 107-7056 E-7 1
Valve Gp - Left Travel / Brake 266-7843 E-5 5
Valve Gp - Lock Solenoid 121-1491 B-5 28
Valve Gp - Main Control 259-7770 D-1 12
Valve Gp - Pilot Control Bucket / Boom 232-4158 C-7 19
Valve Gp - Pilot Control Stick / Swing 232-4157 C-8 18
Valve Gp - Pilot Control Travel 165-9522 D-8 17
Valve Gp - Pilot Manifold 215-5037 B-6 30
Valve Gp - Power Shift Control 225-4518 B-2 33
Valve Gp - Right Travel / Brake 266-7843 E-4 6
Valve Gp - Stick Drift Reduction 153-5233 D-5 11
Valve Gp - Swing Brake Solenoid 121-1491 B-6 26
Valve Gp - Travel Speed Solenoid 121-1491 B-6 25
Note A: See the Parts manual for specific cylinder part number.
Component Locations
7
8
25
26
28
29
30
11
12 13
14
6
4
5
3
1
2
39 41 42 44
33
36
38
32
43
9
10
17
18 19
2120 22
23
DR2 T-OUT2
DR1
PSA1
PSA2
P-IN
Pi 1
P2
PAC
DR6
DR5
DR4 DR3
Pi 2
T-OUT1
HL
APi2
HR
Dr
PAT
A A
C
B
VIEW A-A
VIEW B VIEW C
AL4
BL4 AL3 AL2 AL1 AR1
BL3 BL2 BL1
PTA
PSW
X
BR2
AR4
AR3
BR3
BR1
AR2
R3
R1
aL5 aL4 bL3 aL2 bL1
bR1 bR2 aR3
aR4
Pp2Pp1
dL5
dR5
PL
PR
bL4 aL3 bL2 aL1 dST1 aR1 aR2 aR3
Bpi
BDr
Pp2Pp1
Api
ADr
dsW PiL
R2
TANK
dR4
STICK (2)
BOOM
BUCKET
ATT
TRAVEL (R) STR TRAVEL
TRAVEL (L)
SWING
STICK
BOOM (2)
11
15
Machine Component Locations
Main Control Valve
Pilot Manifold Control Valve
LOCK SWING TRAVEL
RENR7336-00
30 Page, Color 2, DGM
DRAIN / RETURN LINE
LINES GROUP COLOR DESCRIPTIONS
DRIVE PUMP OUTPUT
IDLER PUMP OUTPUT
POWER SHIFT CONTROL CIRCUIT
PILOT PUMP OUTPUT
HYDRAULIC OIL COOLING PUMP OUTPUT
ATTACHMENT CONTROL CIRCUIT
SUPPLY LINE
BUCKET CONTROL & BUCKET CYLINDER CIRCUIT
RIGHT TRAVEL CONTROL & RIGHT TRAVEL MOTOR CIRCUIT
TRAVEL SPEED CONTROL CIRCUIT
STICK CONTROL & STICK CYLINDER CIRCUIT
BOOM CONTROL & BOOM CYLINDER CIRCUIT
HEAVY LIFT CONTROL CIRCUIT
LEFT TRAVEL CONTROL & LEFT TRAVEL MOTOR CIRCUIT
SWING CONTROL & SWING MOTOR CIRCUIT
SWING BRAKE CONTROL CIRCUIT
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
1
2
3
4
5
6
7
8
A
C
D
E
F
1
23
4
56
7
8
A
B
C
D
E
F
B
STICK CYLINDER
SWING MOTOR
DB1
M1
PA1
A
B
PG1
SWING MOTOR
DB2
M2
PA2
A1
B1
DE1
PB1
PG2
PB2
A2
B2
DE2
TRAVEL(L) TRAVEL(R)
SWIVEL GP
JOINT
225-4547
TRAVEL MOTOR (LEFT)
X
AG
BR
T1
T2
L
BR
T1
T2
L
AB
BG
BG
TRAVEL MOTOR (RIGHT)
AG
X
BUCKET CYLINDER
BOOM
CYLINDER
BOOM
CYLINDER
STICK
SWING
BUCKET
BOOM
OUT
IN
L
R OPEN CLOSE DOWN
UP
P1
P2 Pi1 P-IN PSA2 DR1 PSA1
T-OUT2 DR2
DR3 DR4 Pi2 DR5 DR6T-OUT1
B1
A1
A2
B2
OUT
T
PG
PC
IN
Pi1
PS1D0
A4 B1 Dr1 Di PS2 PB
Pi2
a2
a5
A2
a3
PSV
A1
a1
a4
aL5
Dr
HL
R2
X
dL5 (IN,OUT)(DOWN)(OPEN)bL2(FWD)
Pp1
PiH
dST1(FWD)(L)dSWPiL(IN)dR5APi2dR4
R1
Y
AR4
R3
HR
(UP)
aL4
ADr
APi
(OUT)
(R) (L)
(R)
(F)(B)
(BACK)
PSW PTA
(BACK)
(B) (F) PAT BL2 AL2aL2
(CLOSE)
(UP)
BDr
BPi
STICK(2)BOOMBUCKETATCHTRAVEL(R)TRAVEL(L)SWINGSTICKBOOM(2)
A
B
P1
P2
T
Pp2
TP
TT
BACK
T1 T2
FWD
FWD
T3 T4
BACK
JLP
JLT
JRP
JRT
JR1
JR3
JR2
JR4
JL4JL2
JL3
JL1
A1
B1
A2
B2
A3
B3
A4
B4
A5
B5
A6
B6
A7
B7
A8
B8
8
1
7
6
VALVE GP
PILOT
MANIFOLD
215-5037
FILTER GP
RETURN
173-3434
FILTER GP
DRAIN RETURN
126-2075
MOTOR GP
COOLING FAN
242-6904
VALVE GP
CHECK
SLOW RETURN
185-0384
VALVE GP
CHECK COOLER
BYPASS
123-2505
VALVE GP
PILOT CONTROL
STICK/SWING
232-4157
MOTOR GP
LEFT SWING
225-4506
VALVE GP
BOOM/SWING
PRIORITY
232-4102
FILTER GP
PILOT
158-8987
ACCUMULATOR GP
PILOT MANIFOLD
164-6981
NO.1
(TRAVEL)
NO.2
(SWING)
NO.3
(LOCK)
bR1 aR1 aL1 bL1
aR3 bR3bR2 aR2aL3bL3 bL4aR4
BR3 AR3
AR2 BR2
BR1 AR1 AL1 BL1
BR3 AR3
aR3
BR2
AR2
BR1
AR1
bR2
bR1
bL1
BL1
AL1
bL3
bR3
aR2 aR1
PL
PR
aL1
aL3 bL4
PR
PL
aR4
DR
DR1
L2
L3
A
B
SLL1
B
X
MU
A
CV2
MU1
A
CV
MU2
MU1
A
MU2
CV
PUMP GP
COOLING
259-0814
PUMP GP
DRIVE/IDLER
& PILOT
259-0818
DRIVE
IDLER
PILOT
VALVE GP
POWER SHIFT
CONTROL
225-4518
FILTER GP
DRAIN RETURN
126-2075
VALVE GP
PILOT CONTROL
BUCKET/BOOM
232-4158
VALVE GP
PILOT CONTROL
TRAVEL
165-9522
MOTOR GP
RIGHT SWING
225-4506
VALVE GP
LEFT SWING
MOTOR
116-3420
MOTOR GP
LEFT TRAVEL
232-6180
VALVE GP
LEFT
TRAVEL/BRAKE
266-7843
MOTOR GP
RIGHT TRAVEL
232-6180
VALVE GP
RIGHT
TRAVEL/BRAKE
266-7843
VALVE GP
MAIN CNTRL
259-7770
VALVE GP
CHECK
BOOM/STICK(2)
239-8902
VALVE GP
CHECK
STICK
239-8904
VALVE GP
CHECK
BOOM(2)
239-8906
SWITCH AS.
TRAVEL PRESS
106-0179
SWITCH AS.
IMPLEMENT
PRESSURE
106-0179
SENSOR GP
PUMP DRIVE
PRESSURE
221-8869
SENSOR GP
PUMP DRIVEN
PRESSURE
221-8869
VALVE GP
LOCK SOL
121-1491
VALVE GP
SWING
BRAKE SOL
121-1491
VALVE GP
TRAVEL
SPEED SOL
121-1491
FILTER GP
RETURN
173-3434
TANK GP
HYDRAULIC
227-0431
VALVE GP
STICK DRIFT
REDUCTON
153-5233
THIS SCHEMATIC IS FOR THE 345C
Part #: 230-2696 CHG 06
Components are shown installed on a fully operable
machine with the key and engine off and transmission
shifter in neutral.

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