The document provides a schematic and component locations for the hydraulic system of a 312D2 and 313D2 excavator. It includes: - A schematic diagram labeling hydraulic components and lines with callouts and color coding. - Tables listing the components, their part numbers, locations on the machine and in the schematic. - Views showing the physical locations of components on the excavator. - Descriptions of fluid power and electrical symbols used in the schematic.

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. Hydraulic System
312D2 and 313D2 Excavator
©2016 Caterpillar, All Rights Reserved
UENR3860-05
November 2016
ZAA1-Up
TJY1-UP
LCY10001-UP
FAP1-UP
WHJ1-UP
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RDE10001-UP
PLD1-UP
EAB1-UP
Schematic

3. COMPONENT LOCATION
Description
Part
Number
Machine
Location
Schematic
Location
Accumulator Gp - Hydraulic (Charged) 164-6981
Control Gp - Joystick (LH) 297-0533
Control Gp - Joystick (RH) 297-0532
Filter & Valve Gp - Pilot (Hydraulic Oil) 158-8987
Filter Gp - Oil (Hydraulic, Case Drain) 289-8194
Filter Gp - Oil (Hydraulic, Main Return) 259-0869
Manifold Gp - Control (Pilot Oil) 215-5037
Motor Gp - Piston (Left) 357-1821
Motor Gp - Piston (Right) 357-1821
Motor Gp - Swing 170-9893
Pump Gp - Piston 391-9442
Radiator & Hydraulic Oil Cooler Gp 390-8828
Screen Gp - Hydraulic 394-4278
Switch As - Pressure (Implement) 309-5768
Swivel Gp 162-4696
Tank & Filter Gp - Hydraulic 395-1575
Valve Gp - Check (Cooler Bypass) 171-0002
Valve Gp - Main Control 420-2241
Valve Gp - Pilot 369-8503
Valve Gp - Pressure Reducing (Boom Priority) 310-0210
Valve Gp - Shuttle (B) 164-6979
Valve Gp - Travel Counterbalance (Left) 349-9520
Valve Gp - Travel Counterbalance (Right) 349-9520
1 B-4
2 A-8
3 A-7
4 B-3
5 A-3
6 A-4
7 B-5
8 F-8
9 F-7
10 F-6
11 A-3
12 C-2
13 A-4
14 E-5
15 E-7
16 A-4
17 C-2
18 D-4
19 B-8
20 C-3
21 C-6
22 E-8
23 E-7

4. TAP LOCATION
Tap
Number
Description
Schematic
Location
Idler Pump Delivery Pressure
Drive Pump Delivery Pressure
Power Shift Pressure
Pump Case Pressure
Pilot Pump Delivery Pressure
Oil Sampling Port
B-3
A-3
A-2
A-2
B-3
B-3
AA
BB
CC
DD
PG
SOS

5. 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

6. 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

7. SCHEMATIC PART NUMBER: 389-2422 HE 03
Components are shown installed on a fully operable machine with the key and engine off.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations.
312D2 and 313D2 Excavator Hydraulic System
UENR3860-05
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
Components (By number)
YY
52
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
PILOT PUMP OUTPUT
DRIVE PUMP OUTPUT
LEFT TRAVEL CONTROL AND LEFT TRAVEL CIRCUIT
POWER SHIFT CONTROL CIRCUIT
SUPPLY LINE
ATTACHMENT CIRCUIT
SWING CONTROL AND SWING MOTOR CIRCUIT
DRAIN / RETURN LINE
SWING BREAK CONTROL CIRCUIT
IDLE PUMP OUTPUT
TRAVEL SPEED CONTROL CIRCUIT
BUCKET CONTROL AND BUCKET CYLINDER CIRCUIT
RIGHT TRAVEL CONTROL AND RIGHT TRAVEL CIRCUIT
BOOM CONTROL AND BOOM CYLINDER CIRCUIT
STICK CONTROL AND STICK CYLINDER CIRCUIT
(1) ACCUMULATOR GP
(6) FILTER GP
(2) CONTROL GP
(3) CONTROL GP
(4) FILTER & VALVE GP
(5) FILTER GP
(7) MANIFOLD GP
(10) MOTOR GP
(8) MOTOR GP (9) MOTOR GP
(11) PUMP GP
(12) RADIATOR & HYDRAULIC
(13) SCREEN GP
(14) SWITCH AS
(15) SWIVEL GP
(16) TANK & FILTER GP
(17) VALVE GP
(18) VALVE GP
(19) VALVE GP
(20) VALVE GP
(21) VALVE GP
(22) VALVE GP (23) VALVE GP
TRAVEL
COUNTERBALANCE
(RIGHT)
TRAVEL
COUNTERBALANCE
(LEFT)
SHUTTLE (B)
PRESSURE REDUCING
(BOOM PRIORITY)
PILOT
MAIN CONTROL
CHECK (COOLER BYPASS)
HYDRAULIC
PRESSURE (IMPLEMENT)
HYDRAULIC
OIL COOLER GP
PISTON
PISTON (RIGHT)
PISTON (LEFT)
SWING
CONTROL (PILOT OIL)
OIL (HYDRAULIC,
CASE DRAIN)
PILOT (HYDRAULIC OIL)
JOYSTICK (RH)
JOYSTICK (LH)
OIL (HYDRAULIC,
MAIN RETURN)
HYDRAULIC (CHARGED)
AA
BB
DD
CC
SOS
PG
PA1
(OUT)
bR5
(R)
bR4 PSW PTA
(DOWN)
(UP)
BL3 AL3
(CLOSE)
R2
HL
HR
T
(OPEN)
(IN)
dB1
pB1
(DOWN)
dST1
PP
(L)
(IN)
dA1
R1
(FWD)
(FWD)
(BACK) (BACK)
(UP)
BOOM CYLINDER
STICK CYLINDER
BUCKET CYLINDER
Dr
M5
Pn1
PM
M3
M1
A1
S2
S1
A2
M2
M4 A3 PS
Pn2
aR5 aL6
bL6
(OUT)
bL3
aL3
aL5
bL5
PAC
DR2
DR3 DR4 DR5 DR6
DR1
P-IN
Pi1
Pi2
PSA2 PSA1
P1
P2
T-OUT2
T-OUT1
(FWD)
(BACK)
(BACK)
(FWD)
TT
TP
T1
T2
T3
T4
CP1
CP2
JR1
(UP)
JR4
(OPEN)
JR2
(CLOSE)
JR3
(DOWN)
JL3
(IN)
JL1
(OUT)
JL4
(L)
JL2
(R)
DrM
PG
IN
OUT
T
PC
dB
dA
4
7
1
3
6
5
2
TRAVEL(L) TRAVEL(R)
JLP
JLT
JRT
JRP
BOOM
BOOM
STICK
STICK
SWING
SWING
BUCKET
BUCKET
A
B
C
D
E
F
1
2
3
4
5 6
4
5 6 3 2
1
aR3 aR2
bR3 bR1
aR1
bR2
bL1
aL1
bL2
aL4
bL4
BR3 AR3
BR2
AR2 BR1 AR1
BL1
AL1 AL2 BL2
BL4 AL4
aL2
AL2 BL2
BR3
AR3
BL4 AL4
AR1
BR1 BL1
AL1
aR2
bR2
bL4
bR3
aR3
aL4
bL2
aL2
bR1
aR1 aL1
bL1
PR PL
PR
PL
STICK(R)
BOOM(2)
STICK(2)
BUCKET
ATCH
BOOM(1)
TRAVEL(R)
TRAVEL(L)
SWING
STICK(1)
M
TRAVEL
SPEED
CHANGE
SOL.
SWING
BREAK
SOL.
HYD
LOCK
SOL.
T
P1
B1 A1
P2
B2 A2
Pp3
B A
B
A
T1
Pp3
TRAVEL MOTOR (LEFT) TRAVEL MOTOR (RIGHT)
T2 T2
T1
AG BG
BG
BG AG
B A
PR
DR
SWING MOTOR
MU
AR2
BR2
199-0504
349-9520
164-6979
310-0210
369-8503
420-2241
171-0002
395-1575
162-4696
309-5768
394-4278
390-8828
391-9442
357-1821
357-1821
369-9604
215-5037
289-8194
158-8987
297-0532
297-0533
259-0869
164-6981

8. COMPONENT LOCATIONS
23
22
16
15
13
12
10
9
8
6
VIEW ALL CALLOUTS

9. CAB VIEW - TOP
CAB VIEW - TOP
19 3
2
VIEW ALL CALLOUTS

10. MAIN CONTROL VALVE
MAIN CONTROL VALVE
18
17
14
20
21
VIEW ALL CALLOUTS

11. MAIN PUMP
MAIN PUMP
SOS PG
DD
CC
BB AA
11
7
5
4
1
VIEW ALL CALLOUTS