f06377

RENR5514-01September 2003

312C ExcavatorHydraulic System

CBA1-UPCAE1-UPBNN1-UPFDS1-UPCBT1-UP

DR2

T-OUT(2)

PSA1

DR1PSA2

P-IN

Pi1

P2

PAC

P1

DR6

T-OUT(1)

DR5

Pi2

DR4

9 Main Control Valve

NRLbL6 bL5

RBL2

MR

PTAbR4 bR5

bL4 bL3 bL2 bL1 bR1 bR2 bR3

RBL4RBL3

PP PSW RBr3

CLa2

bL4 bL3 bL2 bL1 bR1 bR2 bR3

RBL4

RBL3

dB1 PB1

PP PSW

PBR3

PBR3

BL2

BRCBL1 BR1

BR2BR3

ARCFA1

dA1LCPa1

LCa1

AR3

AR2

LCs

AR1AL1AL2

LCb1

AL3

BL3LCBR

BL4LCa2

AL4LCO

RAL3

aL4

RAL4aL3

RAL2aL1 aR1 aR2 aR3

Pilot Manifold

47

48

49

50

24253031

35

1819 15 14 13 12 11

33

32 28

20

34

51

© 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

BWH1-UPDBN1-UP

Pi2

DR6

PSA2PSA1

TOUT1

DR5

P1

DR1

P2

TOUT2

DR4

DR3

Pi1

PIN

DR2

A B

T

R/G

M2 M2M1

R/G

T

PS

A B

M1

M1

aL5 bL5

HR

HL

R2

aL3 AL3BL3

bL6aL6

bL3

X2

A3

PB1 dB1 dB

X1

S3

PS

Si

A2

A1

M2

Dr

dST1PR

PG

PL

R1

PP

dA1

bR4bR5

PA1 PSW

PTA

Dr

AB

JRP

JRT

JR4JR2

JR3

JR1

TT TP

JLP

JL1

JL2

P1

P

T

P2

JL4

JL3

JLT

A1

A2

A3

A4

A5

A6

A7

A8

B1

B2

B3

B4

B5

C B6

B7

B8

DrB5

J

Au

M4

DrB4DrB7

FE

DrB1M3

M5

B1B2

B6

B3

B5

B4

B4

B5

B3

B6

B2B1

C

DrB3

PS

158-82351 2 3

4 5 6

7

89

1011 12 13 14 15 17 1816 19

20 21

2322

24 25

26 27

28

29

30 31

32 33

34

35

36 37

38

39

40 41

42

43 44

45 46

4847 49 50

51

52

53 54

55

56

57

58

PILOT LINE

DRAIN LINE

Hydraulic Schematic

MAIN CONNECTOR LINE

6

4

5

1

7

44 45

46 53 5451

555657

2

3

41

940

39

ItemComponent

STANDARD COMPONENTS

ComponentNo.ItemNo.

123456789

1011121314151617181920212223242526272829

32

35363738394041

3031

3334

45464748

42

4443

5049

51

54555657

5253

Swing Motor

Travel Motor (Left)

Travel Motor (Right) Stick Cylinder Boom Cylinder

Bucket Cylinder

Swivel

Pressure Switch (Implement) Main Control Valve

Stick I Control Valve Pilot Control Valve (Travel)

Swing Control Valve Left Travel Control Valve

Right Travel Control Valve

Boom I Control Valve

Boom Drift Reduction Valve

Line Relief Valve (Boom Cylinder Head End)

Attachment Control Valve

58

Bucket Control Valve

Line Relief Valve (Stick Cylinder Rod End)

Line Relief Valve (Stick Cylinder Head End)

Pilot Spool Valve

Stick Drift Reduction Valve

Swing Control Valve

Stick Regeneration Control Valve

Main Relief (Implement/Swing)

Striaght Travel Control Valve

Line Relief Valve (Boom Cylinder Rod End)

Pilot Spool Valve

Boom II Control Valve

Stick II Control Valve

Line Relief Valve (Bucket Cylinder Head End)

Line Relief Valve (Bucket Cylinder Rod End) Negative Flow Line Relief Valve (Right)

Negative Flow Line Relief Valve (Left)

Pilot Control Valve (Stick/Swing) Pilot Control Valve (Boom/Bucket)

Pressure Switch (Travel)

Pressure Reducing Valve (Boom Priority)

Slow Return And Bypass Check Valves

Oil Cooler

Hydraulic Tank

Logic Valve

Relief Valve (Hydraulic Tank)

Drain Filter

Return Filter

Pilot Control Solenoid (Travel Speed)

Pilot Control Solenoid (Swing Parking Brake)

Hydraulic Lock Control Valve Hydraulic Lock Solenoid

Pilot Oil Manifold

Accumulator

Pilot Relief

Pilot Filter

Left Pump

Right Pump

Pilot Pump

Proprtional Reducing Valve (Power Shift)

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