INTERACTIVE SCHEMATIC
The Bookmarks panel will allow you to
quickly navigate to points of interest.
Click on any text that is BLUE and underlined.
These are hyperlinks that can be used to navi-
gate the schematic and machine views.
When only one callout is showing on a machine view this
button will make all of the callouts visible. This button is
located in the top right corner of every machine view page.
VIEW ALL CALLOUTS
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
To set your screen resolution do the following:
RIGHT CLICK on the DESKTOP.
Select PROPERTIES.
CLICK the SETTINGS TAB.
MOVE THE SLIDER under SCREEN RESOLUTION
until it shows 1024 X 768.
CLICK OK to apply the resolution.
This document is best viewed at a
screen resolution of 1024 X 768.
FUNCTION
Zoom In
HOTKEYS (Keyboard Shortcuts)
Zoom Out
Fit to Page
Hand Tool
“CTRL” / “+”
KEYS
“CTRL” / “-”
“CTRL” / “0” (zero)
“SPACEBAR” (hold down)
Find
“CTRL” / “F”
RENR6079-02
September 2008
938G Series II Wheel Loader
Hydraulic System
RTB1-UP
CRD1-UP
PHN1-UP
B9Y1-UP
Printed in U.S.A.© 2008 Caterpillar, All Rights Reserved
COMPONENT LOCATION
Description
Part Number
Machine
Location
Schematic
Location
Accumulator - Brakes 213-8773 1 D-7
Connector 113-9234 2 E-4
Cooler - Oil - Core Asy. 189-0224 3 D-4
Cylinder Gp. - Lift 128-7678 4 F-4
Cylinder Gp. - Steering 139-3312 5 F-2
Cylinder Gp. - Tilt 137-7865 6 F-4
Filter Element 1R-0722 7 A-4
Metering Pump - HMU (Steering) 113-0061 8 D-2
Motor Gp. -Fan 191-2943 9 D-5
Pump Gp. - Piston (Hyd Fan) 215-8298 10 B-5
Pump Gp - Steerng, Impl, Brakes 105-2140 11 B-7
Tank - Hydraulic 160-3408 12
A-5
Valve - Ball (Pilot Shut Off) 156-5726 13 E-6
Valve - Brake (Tandem) 215-3687 14 E-7
Valve - Breaker Relief (Hyd Tank) 133-1963 15 B-4
Valve - Check (Lift Make Up) 9T-7634 16 F-4
Valve - Check (Pilot) 9T-3096 17 C-7
Valve - Check (Ride Control) 9T-3096 18 F-4
Valve - Control (Reducing/Selector) 6E-3078 19 E-6
Valve - Control (Steering) 9T-7420 20 E-2
Valve - Cooler Bypass 145-8983 21 C-4
Valve - Diverter (Suplm Steering) 141-2597 22 C-2
Valve - Dual Accumulator Charge 134-5106 23 D-7
Valve Gp - Control (2V) 133-4238 24 E-4
Valve Gp - Pilot (2V single axis) 164-2796 25 E-4
Valve - Relief (Aux. Cyl) 186-0809 26 E-5
Valve - Relief (Aux Cyl) 186-0809 26 E-5
Valve - Relief (Main Impl) 108-6428 27 E-5
Valve - Relief (Steering Backup) 6E-3447 28 E-2
Valve - Relief (Steering Crossover) 9T-7419 29 E-2
Valve - Relief (Tilt Cyl - Dump) 186-0809 26 E-4
Valve - Relief (Tilt - Rackback) 185-7712 30 E-4
Accumulator 221-1753 31 F-3
Accumulator - Ride Control 124-9439 32 F-3
Cylinder Gp. - Auxiliary Supplier 33 F-5
Pump Gp - Supplemental Steering 217-3015 34 B-2
Valve - Check (Ride Control) 104-7108 35 E-3
Valve - Control (Aux) 164-2800 36 E-5
Valve - Control (Lift) 164-2801 37 E-4
Valve - Control (Tilt) 164-2797 38 E-4
Valve Gp - Control (Aux) 6E-5958 39 E-5
Valve Gp - Control (3V) 133-4239 40 E-4
Valve - Shuttle (Ride Control) 141-1481 41 E-3
Valve - Solenoid (Ride Control) 149-2610 42 F-3
Attachments
TAP LOCATION
Schematic
Location
BB
Pressure
Tap
Description
GG
HH
JJ
C7
Implement Pilot Pump Pressure
Steering Pump Pressure
Hand Metering Unit Supply Pressure
Implement Pump Pressure
E6
C7
C2
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 PEDALGENERAL 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 ACTINGSINGLE 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
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
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling, Sensor - by letter)
YY
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
PILOT PUMP OUTPUT
MAIN PUMP OUTPUT
SUPPLEMENTAL STEERING PUMP OUTPUT
STEERING CIRCUIT
SCAVENGE PUMP
SUPPLY LINE
BRAKE CIRCUIT
LIFT CIRCUIT
DRAIN / RETURN LINE
AUXILARY CIRCUIT
TILT CIRCUIT
THIS SCHEMATIC IS FOR THE 938G SERIES II WHEEL LOADER
MEDIA NUMBER: RENR6079-02
PART NUMBER: 192-9949, CHANGE: 01, VERSION: (-)
Components are shown installed on a fully operable machine.
Refer to the appropriate Service Manual for Troubleshooting, Specifications.
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
DUMP
C1
C2
P1
T1
RAISE
LOWER
RACKBACK
(5) CYLINDER GP
(STEERING)
139-3312
(20) VALVE GP
(STEERING
CONTROL)
9T-7420
(29) RELIEF VALVE
(STEERING
CROSSOVER)
9T-7419
(28) RELIEF
VALVE
(STEERING
BACKUP)
6E-3447
(8) HMU
113-0061
(11) PUMP GP
105-2140
(17) CHECK
VALVE
9T-3096
(22) DIVERTER
VALVE GP
(SUPPLEMENTAL
STEERING)
(ATCH)
141-2597
(34) PUMP GP
(SUPPLEMENTAL
STEERING)
(ATCH)
217-3015
(12) HYD TANK GP
160-3408
(7) FILTER
ELEMENT
1R-0722
(15) BREAKER
RELIEF
VALVE GP
133-1963
(10) PISTON
PUMP GP
(HYD FAN)
215-8298
(3) CORE AS.
(HYD OIL
COOLER)
189-0224
(21) BYPASS VALVE
(HYD OIL COOLER)
145-8983
(9) MOTOR GP
(FAN DRIVE)
191-2943
(33) CYLINDER GP
(AUX)
(ATCH)
(6) CYLINDER GP
(TILT)
137-7855
(4) CYLINDER GP
(LIFT)
128-7678
(18) CHECK
VALVE
9T-3096
(19) VALVE GP
6E-3078
(13) VALVE GP
156-5726
(32) ACCUMULATOR
RIDE CONTROL
124-9439
221-1753
(41) SHUTTLE VALVE
(ATCH)
141-1481
(42) SOLENOID
VALVE
(RIDE CONTROL)
(ATCH)
149-2610
(35) CHECK VALVE
(RIDE CONTROL)
(ATCH)
104-7108
(16) CHECK
VALVE
9T-7634
(24) MAIN CONTROL
VALVE GP
133-4238 (2V)
(39) VALVE GP
(ATCH)
6E-5958 (1V)
(27) VALVE GP
(MAIN IMPL
RELIEF)
108-6428
(26) RELIEF
VALVE
(LINE)
186-0908
(30) RELIEF
VALVE
(LINE)
185-7712
(25) VALVE GP
(PILOT)
164-2796 (2V)
OSCILLATING REAR AXLE
FIXED FRONT AXLE
(23) DUAL ACCUMULATOR
CHARGE VALVE
134-5106
LEFT AND RIGHT
PEDAL ASSEMBLY
NO
NC
C
(1) HYDRAULIC
ACCUMULATOR
213-8773
(1) HYDRAULIC
ACCUMULATOR
213-8773
(14) TANDEM
BRAKE
VALVE
215-3687
TO XMISSON
CONTROL
TO STOP LAMP
SWITCH (NC)
BB
(31) ACCUMULATOR
(ATCH)
(2) CONNECTOR (6 PL)
113-9234
TO AUDIBLE
AND VISUAL
SIGNLS SWITCH
IS NORMALLY
CLOSED
175-3244
BRAKES
HYDRAULIC COOLING
STEERING
JJ
GG
HH
(36) VALVE GP
CONTROL (AUX)
(ATCH)
164-2800 (3V)
(37) VALVE GP
(LIFT)
(ATCH)
164-2801 (3V)
(38) VALVE GP
(TILT)
(ATCH)
164-2797 (2V)
(40) VALVE GP
CONTROL
(ATCH)
133-4239 (3V)
COMPONENT LOCATIONS
JJ
JJ
HH
HH
GG
GG
BB
BB
42
42
41
41
40
40
39
39
38
38
37
37
36
36
35
35
34
34
33
33
32
32
31
31
30
30
29
29
28
28
27
27
26
26
25
25
24
24
23
23
22
22
21
21
20
20
19
19
18
18
17
17
16
16
15
15
14
14
13
13
12
12
11
11
10
10
9
9
8
8
7
7
6
6
5
5
5
4
4
4
3
3
2
2
2
1
1
VIEW ALL CALLOUTS
