cat 325

1. INTERACTIVE SCHEMATIC
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Cover Page
Information
Schematic
Machine Views
Component Table
Tap Table
Fluid Power Symbols
Electrical Symbols
Front Frame
Rear Frame
Tap Views
Features
Options
Bookmarks X
EC-C3
EC-C2 E-C60
EC-C1
E-C61
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2. ©2002 Caterpillar, All Rights Reserved Printed in U.S.A.
RENR5366-01
June 2002
325C Excavator
Hydraulic System
325C:
BLA 1-UP
BTD1-UP
BFE1-UP
AMH1-UP
BKH1-UP
BMM1-UP
BKT1-UP
BKW1-UP
BLX1-UP

3. COMPONENT LOCATION
Description
Part
Number
Machine
Location
Schematic
Location
Accumulator Gp 4I-1536 1 B-4
Cylinder Gp - Boom 179-9788 2 E-2
Cylinder Gp - Bucket 158-8998 3 E-3
Cylinder Gp - Stick 179-9790 4 E-6
Filter Gp - Drain 126-2075 5 A-3
Filter Gp - Pilot 158-8987 6 A-3
Filter Gp - Return 188-4140 7 A-5
Manifold Gp - Pilot Control 215-5037 8 B-4
Motor Gp - Fan 179-9778 9 A-6
Motor Gp - Swing 179-9775 10 E-5
Motor Gp - Travel (Left) 215-9952 11 E-4
Motor Gp - Travel (Right) 215-9952 12 E-3
Switch As - Pressure 167-3466 13 C-6
Switch As - Pressure (Implement / Swing) 167-3466 14 B-6
Swivel Gp 159-7841 15 D-4
Tank Gp - Hydraulic 176-4618 16 A-4
Valve Gp - Attachment Control 171-0146 17 C-3
Valve Gp - Boom Drift Reduction 264-9963 18 D-2
Valve Gp - Logic 185-0462 19 B-7
Valve Gp - Main Control 258-0284 20 C-3
Valve Gp - Oil Cooler Bypass Check 173-4672 21 A-6
Valve Gp - Pilot Control (Boom / Bucket) 206-3303 22 C-6
Valve Gp - Pilot Control (Swing / Stick) 206-3304 23 C-7
Valve Gp - Pilot Control (Travel) 158-8250 24 C-7
Valve Gp - Pilot Relief 215-4909 25 A-3
Valve Gp - Pressure Reducing (Boom/Swing Priority) 232-4102 26 B-3
Valve Gp - Relief (Cooling Pump) 204-2772 27 A-6
Valve Gp - Relief (Negative Flow Control) 109-5152 28 C-5
Valve Gp - Solenoid (Hydraulic Activation) 121-1491 29 A-4
Valve Gp - Stick Drift Reduction 264-9962 30 D-5
Valve Gp - Variable Swing Priority 153-5295 31 C-4

4. 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 PEDAL
GENERAL 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 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

5. 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

6. 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.
SCHEMATIC PART NUMBER: 177-2825, CHANGE: 07, VERSION: HE
MEDIA NUMBER: RENR5366-01
THIS SCHEMATIC IS FOR THE 325C EXCAVATOR HYDRAULIC SYSTEM
A
B
C
D
E
1
2
3
4
5
6
7
A
B
C
D
E
1
2
3
4
5
6
7
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
YY
(52) VALVE GP - CONTROL
138-1234
Callout Number
(Machine Location from
Component LocationsTable)
Component
Name
Part Number
IN
DR
OU T
B Dr
P i2
(L OC K )
P i
Dr1
A 3 M1
M2
A 1
A 2
N O3
P IN
PAC
P i1
P 2
P 1 P S A 2
DR 6
DR 5
P S A 1
DR 4
DR 3
DR 2
DR 1
B P 1 B T
B A
T
T OU T 2
T OU T 1
(L OW E R )
A 4
(OU T )
(IN )
B OOM
B U C K E T
S W IN G
S T IC K
T R AV E L (R )
I
T
D
OC S
P IL OT
S 1
S 3
L
B
A
P n1
T R AV E L (L )
A
B
C
D
P s M2
P s 1
P s M1
(R A IS E )
(R E V )
(F W D)
(R ) (OP E N )
(C L OS E )
(L )
(F W D)
(R E V )
(T R AV E L )
F
E
G
T
P 1
P 2
B 2
A 2 B 1
B 8
B 7
B 6
C B 5
B 4
B 3
B 2
B 1
A 8
A 7
A 6
A 5
A 4
P n2
A 3
A 2
A 1
DrM
M3
S Dr
F R
R R
B OOM(1 )
B U C K E T
AT C H
T R AV E L (R )
S W IN G
S T
M4
P B 2
P m
P B 1
S P 1
P B 5
S P 2
P i3 Di3 DS T
(IN )
P R
P L
T
(OU T )
A R 4
R 1
B R 4
A R 3
B R 3
A R 2
B R 2
Dr2
P s 2
S P i
DB 1
DB 2
S P 3
(R A IS E )
A R 1
B R 1
B R 5
DB 5
DB 6
S 4
P B 6
Di4
P i4
A L 1
bL 3
A R 5
P
G
G 2
G 1
A L 4
B L 1
C
L
O
S
E
A L 2
O
P
E
N
A B
A 1
R 3
B L 2
B P i
A L 3
D
O
W
N
R 2
B P 3
L
R
S T IC K (1 )
B P 2
S T IC K (2 )
B OOM(2 ) T R AV E L (L )
bR 4
a R 5
P i1
a R 4
bR 5
H R
Di1
a R 3
bR 3
a R 2
bR 2
a R 1
bR 1
a L 1
bL 1
H L
a L 2
bL 2
bL 4 P i2
a L 4
Di2
I
N
U
P
P p3
P p3
O
U
T
N O1
DR
U
(S W
PA R K IN G )
B L 3
a L 3
MU
DR
A
B
P G
6
BOOM II
CONTROL
VALVE
STICK
REGENERATIVE
VALVE
LINE RELIEF VALVE
(STICK CYLINDER ROD END)
STICK
I CONTROL
VALVE
SWING
CONTROL
VALVE
STRAIGHT TRAVEL
CONTROL
SOLENOID
STRAIGHT TRAVEL
CONTROL
VALVE
LEFT TRAVEL
CONTROL
VALVE
MAIN RELIEF
VALVE
RIGHT TRAVEL
CONTROL
VALVE
LINE RELIEF
VALVE
(STICK CYLINDER
HEAD END)
STICK
UNLOADING
VALVE
BUCKET
CONTROL
VALVE
BOOM I
CONTROL
VALVE
STICK II
CONTROL
VALVE
BOOM
REGENERATION
VALVE
NEGATIVE
FLOW CONTROL
RELIEF
VALVE
LINE
RELIEF VALVE
(BOOM CYLINDER
ROD END)
LINE RELIEF VALVE
BUCKET CYLINDER
HEAD/ROD END
SOLENOID
VALVE
(TRAVEL
SPEED)
SOLENOID
VALVE
(SWING PARKING
BRAKE)
HYDRAULIC
ACTIVATION
VALVE
LEFT
PUMP
RIGHT
PUMP
PILOT
PUMP
COOLING
PUMP
PROPORTIONAL
REDUCING VALVE
PRESSURE SWITCH
(RIGHT PUMP)
PRESSURE SWITCH
(LEFT PUMP)
SLOW RETURN
CHECK VALVE
OIL COOLER
(2) CYLINDER GP
BOOM
179-9788
(3) CYLINDER GP
BUCKET
158-8998
(4) CYLINDER GP
STICK
179-9790
(11) MOTOR GP
TRAVEL (RIGHT)
215-9952
(12) MOTOR GP
TRAVEL (RIGHT)
215-9952
(10) MOTOR GP
SWING
179-9775
(14) SWITCH AS
PRESSURE
(IMPLEMENT / SWING)
167-3466
(27) VALVE GP
RELIEF
(COOLING PUMP)
204-2772
(9) MOTOR GP
FAN
179-9778
(21) VALVE GP
OIL COOLER
BYPASS CHECK
173-4672 (7) FILTER GP
RETURN
188-4140
(29) VALVE GP
SOLENOID
(HYDRAULIC
ACTIVATION)
121-1491
(16) TANK GP
HYDRAULIC
176-4618
(5) FILTER GP
DRAIN
126-2075
(6) FILTER GP
PILOT
158-8987
(25) VALVE GP
PILOT RELIEF
215-4909
(19) VALVE GP
LOGIC
185-0462
(23) VALVE GP
PILOT CONTROL
(SWING / STICK)
206-3304
(24) VALVE GP
PILOT CONTROL
(TRAVEL)
158-8250
(13) SWITCH AS
PRESSURE
167-3466
(22) VALVE GP
PILOT CONTROL
(BOOM / BUCKET)
206-3303
(15) SWIVEL GP
159-7841
(20) VALVE GP
MAIN CONTROL
258-0284 (17) VALVE GP
ATCH CONTROL
171-0146
(18) VALVE GP
BOOM DRIFT
REDUCTION
264-9963
(8) MANIFOLD GP
PILOT CONTROL
215-5037
(1) ACCUMULATOR GP
4I-1536
(30) VALVE GP
STICK DRIFT
REDUCTION
264-9962
(28) VALVE GP
RELIEF
(NEGATIVE FLOW
CONTROL)
109-5152
(31) VALVE GP
VARIABLE
SWING
PRIORITY
153-5295
(26) VALVE GP
PRESSURE REDUCING
(BOOM / SWING PRIORITY)
232-4102

7. MACHINE COMPONENT LOCATIONS
OIL COOLER
COOLING PUMP
PROPORTIONAL
REDUCING VALVE
RIGHT PUMP
PILOT PUMP
LEFT PUMP
25
24
23 22
20
16
15
14
13
12
11
10
9
8 7
6
5
4
3
2
1
VIEW ALL CALLOUTS

8. MAIN CONTROL VALVE
R
S/N
P/N
177-2800
Pi1
R3
HR
Pi4
HL
Pi2
aR5 aR4 aR3 aR2 aR1 aL1 aL2 aL3 aL4
AR5 AR4 AR3 AR2 AR1
BR5
BR4 BR2
BR1
R1
Pi4
AL1 AL2 AL3
AL4
BL1
BL2
BL3
R2
Pi3
bR5
bR4
bR3 bR2 bR1
DST bL1 bL2 bL3 bL4
BR3
NEGATIVE FLOW
CONTROL RELIEF VALVE
LINE RELIEF VALVE
(BUCKET ROD END)
STICK II
CONTROL VALVE
BOOM I
CONTROL VALVE
BUCKET
CONTROL VALVE
LINE RELIEF VALVE
(BOOM CYLINDER
HEAD / ROD END)
BOOM II
CONTROL VALVE
LINE RELIEF VALVE
(STICK CYLINDER
HEAD END)
STICK I
CONTROL VALVE
SWING
CONTROL VALVE
LEFT TRAVEL
CONTROL VALVE
MAIN RELIEF
VALVE
RIGHT TRAVEL
CONTROL VALVE
STRAIGHT TRAVEL
CONTROL SOLENOID
STRAIGHT TRAVEL
CONTROL VALVE
BOOM REGENERATION
VALVE
STICK REGENERATION
VALVE
28
21
17
VIEW ALL CALLOUTS

9. PILOT OIL MANIFOLD
PAC
DR2
T-OUT
PSA1
PSA2
DR1
P-IN
P2
DRG
T-OUT
DR5
Pi2
RD4
RD3
P1
HYDRAULIC
ACTIVATION VALVE
SOLENOID VALVE
(SWING PARKING
BRAKE)
SOLENOID VALVE
(TRAVEL SPEED)
29