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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