FLUID POWER SYMBOLS

SENR1603-01
BASIC COMPONENT SYMBOLS
April 1997
MAIN AUX.
PUMP: VARIABLE and
PUMP or MOTOR FLUID CONDITIONER SPRING CONTROL VALVES RESTRICTION LINE RESTRICTION 2-SECTION PUMP PRESSURE COMPENSATED
(FIXED)

VARIABILITY SPRING LINE RESTRICTION PRESSURE HYDRAULIC PNEUMATIC LINE RESTRICTION ATTACHMENT
(ADJUSTABLE) (VARIABLE) COMPENSATION ENERGY TRIANGLES VARIABLE and PRESSURE
COMPENSATED

VALVES
VALVE ENVELOPES VALVE PORTS

ONE POSITION TWO POSITION THREE POSITION TWO-WAY THREE-WAY FOUR-WAY

CONTROL VALVES CHECK VALVES

AB AB

P T P T
BASIC SPRING SHUTTLE PILOT
NORMAL POSITION SHIFTED POSITION INFINITE POSITION
SYMBOL LOADED CONTROLLED

MEASUREMENT ROTATING SHAFTS

PRESSURE TEMPERATURE FLOW UNIDIRECTIONAL BIDIRECTIONAL

FLUID STORAGE RESERVOIRS

325B and 325B L Excavators VENTED PRESSURIZED RETURN ABOVE FLUID LEVEL RETURN BELOW FLUID LEVEL

Hydraulic System COMBINATION CONTROLS

Common Piping (Attachment) SOLENOID SOLENOID

or MANUAL
SOLENOID SOLENOID and
PILOT or MANUAL
SERVO THERMAL DETENT
and PILOT

325B: 325B L: MANUAL CONTROL SYMBOLS

8PR1-Up 8RR1-Up
1GS1-Up PUSH-PULL LEVER MANUAL SHUTOFF GENERAL MANUAL PUSH BUTTON PEDAL SPRING

1HS1-Up
PILOT CONTROL SYMBOLS
RELEASED PRESSURE REMOTE SUPPLY PRESSURE

EXTERNAL RETURN INTERNAL RETURN SIMPLIFIED COMPLETE INTERNAL

SUPPLY PRESSURE

ACCUMULATORS CROSSING AND JOINING LINES HYDRAULIC AND PNEUMATIC CYLINDERS

SPRING LOADED GAS CHARGED LINES CROSSING LINES JOINING SINGLE ACTING DOUBLE ACTING

HYDRAULIC PUMPS HYDRAULIC MOTORS INTERNAL PASSAGEWAYS

FIXED VARIABLE DISPLACEMENT FIXED VARIABLE DISPLACEMENT THREE TWO

INFINITE
DISPLACEMENT NON-COMPENSATED DISPLACEMENT NON-COMPENSATED POSITIONING POSITION POSITION

UNIDIRECTIONAL UNIDIRECTIONAL

FLOW IN ONE PARALLEL CROSS FLOW ALLOWED IN

BIDIRECTIONAL BIDIRECTIONAL DIRECTION FLOW FLOW EITHER DIRECTION

© 1997 Caterpillar Printed in U.S.A.

All Rights Reserved

Electrical Symbols Table

Hydraulic Symbols (Electrical)

G M
Transducer Transducer Generator Electric Motor
(Fluid) (Gas / Air)

SENR1603-01
Pressure Switch Pressure Switch Temperature Switch Electrical Wire
(Adjustable)

Electrical Symbols (Electrical)

16 Page
T
Pressure Temperature Level Flow
Symbol Symbol Symbol Symbol

Wire Number Identification Codes

Electrical Schematic Example Hydraulic Schematic Example

Current Standard Current Standard

Harness identification code
This example indicates
wire 135 in harness "AG". Wire
Circuit Number Wire Color
Identification

325-AG135 PK-14
325-PK
Circuit Identification Wire Color Wire Gauge
Number

Previous Standard
Wire Color
Wire

325-PK-14
B A
Circuit Number Wire Gauge
Identification (EXAMPLE VALVE)
 MAIN CONNECTOR LINE

PILOT LINE
TRAVEL MOTOR (LEFT) TRAVEL MOTOR (RIGHT)
Hydraulic Schematic DRAIN LINE

SWING
115-8581 MOTOR
1
This Attachment Schematic is intended to
2
be used in conjunction with the Standard
Hydraulic Schematic in this Service Manual
PG

DR
Pp3
Pp3
MU
T T

STICK CYLINDER

1
BUCKET CYLINDER BOOM CYLINDERS
3 8 9

A B B A
4 5 6 7
B A

SWIVEL
3

CB2

CA
CD

CB1

AL1 BPi BP2

APi AP2 (F)
ADr
BL4
BDr
BR3 aL2
aR3 BR1 aL4
dR4 PSL AT BR2 AR2 aR2 aR1 PSW PTA BL2 AL2 aL3 BL3 AL3 BP3 aL5
AP1 AR1 aL1 BP1 BT
R1 AR3 R3 (L) (R) (B) (F)
BL1
(B) AL4 R2 1 2

R4
5 STICK(2)
HL
R3

6 AR4
HR

BOOM(2)
Y DR
BOOM(1)
ATCH FOR BUCKET X
STICK (1) SWING TRAVEL(L) TRAVEL(R)
DOUBLE
aR4 bR3 PiL dSW bR2 bR1 dST1 PR PL PP bL1 PAT bL2 ACTION bL3 PiB bL4
7 dL5

ATTACHMENT COMPONENTS
Item Component
No.
1 Ball Valve
2 Check and Relief Valve
3 Pressure Valve
TT TP JLP JLT 4 Check Valve
5 Pressure Control Valve
SENR1603-01

6 Ball Valve
DOUBLE
7 Orifice Tee
STICK
JL3 JL1
SWING
JL4 JL2
JRP JRT ACTION
P T
8 8 Pilot Valve
PSA
PEU
C/V
JPi
Pi5
Pi8

TLA2 TRA2 Pressure Switch

SINGLE 9
TLA1 TRA1 ACTION
(SWING)
TRAVEL(L) TRAVEL(R) (PUMP)
16 Page, B/W

BUCKET
JR4
JR2
BOOM
JR3
JR1
6 2 1

9
R2
(LEVELING) (TRAVEL) X1
(RELIEF)
PAC

M3
SP
SB5 SB4 SB3 SB2 ST SB1 X3
A1
M1
A B C J
TOUT

PG
DR1
DR2
DR3
DR4
DR5

DR6

PIN

S
Pi3

Pi2

Pi1

SA5 SA4 SA3 SA1

SA2 A2
M2
1 2 3
A3

X2
R1

R1