RENR6667-01September 2003

304 CR Excavator

NAD1-UPBTN1-UP

Hydraulic System

P3

T2B9

A9 A8

B8

A7

B7 B6

A6 A5 A4

B5 B4

P2

P1

A3

B3

B2

A2

T1

B1

A1

Main Control Valve

Pilot Oil Manifold

24

2220 18 31

29 13

2627 2830

32

15

19

21

23

25

12

f05648

B A

PAC

4341

44

40

16

17

2003 CaterpillarAll Rights Reserved

Printed in U.S.A.

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)

PRESSURECOMPENSATION

PUMP: VARIABLE andPRESSURE COMPENSATED

ENERGY TRIANGLESHYDRAULIC PNEUMATIC

MEASUREMENT

PRESSURE TEMPERATURE FLOW

ROTATING SHAFTS

UNIDIRECTIONAL BIDIRECTIONAL

PUSH-PULL LEVER PEDALGENERAL MANUAL PUSH BUTTON SPRING

MANUAL CONTROL SYMBOLS

HYDRAULIC MOTORS

FIXEDDISPLACEMENT

VARIABLE DISPLACEMENTNON-COMPENSATED

UNIDIRECTIONAL

BIDIRECTIONAL

HYDRAULIC PUMPS

FLUID STORAGE RESERVOIRS

CROSSING AND JOINING LINES

VALVE ENVELOPES VALVE PORTS

BASIC COMPONENT SYMBOLS

FLUID CONDITIONERPUMP or MOTOR

FLUID POWER SYMBOLS

FIXEDDISPLACEMENT

VARIABLE DISPLACEMENTNON-COMPENSATED

UNIDIRECTIONAL

BIDIRECTIONAL

VALVES

PILOT CONTROL SYMBOLSRELEASED PRESSURE

EXTERNAL RETURN INTERNAL RETURN

REMOTE SUPPLY PRESSURE

SIMPLIFIED COMPLETE INTERNALSUPPLY 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

TWOPOSITION

INFINITEPOSITIONING

FLOW IN ONEDIRECTION

FLOW ALLOWED INEITHER DIRECTION

THREEPOSITION

CROSSFLOW

PARALLELFLOW

INTERNAL PASSAGEWAYS

NORMAL POSITION

A B

P T

A B

P TSHIFTED POSITION INFINITE POSITION

CONTROL VALVES

L3 STICK L1 L4 SWING L2

P TP

R3 BOOM R1 R2 BUCKET R4

T

Pa2,Pi1 Pb2,Pi4 Pa1 Pb1 Pb5 Pa5 Pa7 Pb7

P

Pb3(LH)

Pa3

4 TRAVEL1

Pb4

2

Pa4

TRAVEL(RH)

P

2 1

Pb8Pa8

P

T

Pa9 Pb9

C A PAC B

D

T

P

T

M

ENGINE

P1 P2 P4 P3

Pb1 Pb2 Pb3 P1T1

Pp P2

B A

P

Dr

B A

P

DrDr

A

A

C

C

D

D

B

B

DBSH

PG

A M B

F

F E

E

G G

P P

A1 B1 B2Pa1

DR1Pi1

A2Pa2

A7 B7A8 B8 A9 B9Pa7

Pa8 Pa9

T2

Pi4Pb9Pb8Pi3Pb7

B3 PsPa3 Pa4

B4 A4Pa5

B5 A5Pa6

B6A6A3

Pb4 Pb5 Pb6 Pi2

Hydraulic Schematic222-0614

T

B A

DR2

B6 A6

Pb6Pa6

T1 P

T

B A

BOOM CYLINDER

C2

V2 Pi1

A8 B8

R3R1

STICK CYLINDER BOOM CYLINDER

L3 L1 R1 R3

B1A1

C1D1

A2B2

L3R3

D2C2

R1L1

BUCKET CYLINDER

A7 B7

R2R4

PILOT LINE

DRAIN LINE

MAIN CONNECTOR LINE

SECOND AUXILIARY FUNCTION ATTACHMENT

ItemComponent

STANDARD COMPONENTS

ComponentNo.ItemNo.

123456789

101112131415161718192021222324

1 2 3

45

6

7 8 9

66

6

10 11

33

34

13 14

15 16 1718

26 27 28

29

30

31

32

19 20

21

2223

24 25

3536

37

3839

45

46

40 41 4243

44

4748

49

19

5 7 5

4

13

49

25

Travel Motor (Left)

Travel Motor (Right)

Swing Motor

Bucket Cylinder

Boom Cylinder

Swivel

Stick Cylinder

Blade Cylinder

Pilot Control Valve (Boom/Bucket)

Pilot Control Valve (Stick/Swing)

Main Control Valve

Bucket Control Valve

Boom I Control Valve

Stick Control Valve

Attachment Control Valve

Flow Switching Valve

Swing Control Valve

Blade Control Valve

Boom II Control Valve

Boom Drift Reduction Valve

Left Travel Control Valve

Right Travel Control Valve

Swing Boom Cylinder

Swing Boom Control Valve

Main Relief Valve

26272829

Line Relief Valve (Boom Cylinder Head End)

Line Relief Valve (Boom Cylinder Rod End)

Line Relief Valve (Bucket Cylinder)

303132333435363738394041424344454647484950515253545556 Quick Disconnects

Joystick Control Selector Valve

Ball Valve

Ball Valve

Ball Valve

Pilot Control Valve (Work Tool)Boom Lowering Control Valve

Hydraulic Tank

Pilot Control Valve (Blade)

Return Filter

Accumulator

Pilot Manifold

Oil Cooler

Swing Boom PumpPilot Pump

Left Pump

Right PumpPilot Control Valve (Travel)

Manifold

Line Relief Valve (Stick Cylinder Head End)

Line Relief Valve (Stick Cylinder Rod End)

12

5354

52

51

AUXILIARY HYDRAULIC SYSTEM

50

15

18 15

55

BOOM LOWERING CONTROL VALVE JOYSTICK CONTROL SELECTOR

56 56

Attachment Schematics

Solenoid Valve (Parking Brake Release)

Solenoid Valve (Hydraulic Activation Control)

Pilot Relief Valve

Relief Valve

Pilot Control Valve (Swing Boom)

P3

Main Relief Valve

Main Relief Valve

f05647

33 93

45 6 48 39

2

10

1

114055

5134478

35 36 37 38

7

4

50

39

4055

33

34 47 51 1 2

35 36 37 38

10 11

8

48

5

45

123

6