938G Wheel Loader And
Hydraulic System
IT38G Integrated Toolcarrier
IT38G:
7BS1-UP
1CW1-UP
938G:
4YS1-UP
6WS1-UP
8RS1-UP
9HS1-UP
© 2012 Caterpillar, All Rights Reserved Printed in U.S.A.
SENR6797 - 01
January 2012
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)
PUMP
(2 - SECTION)
SPRING
(ADJUSTABLE)
VARIABILITY LINE RESTRICTION
(VARIABLE)
PRESSURE
COMPENSATION
PUMP
(VARIABLE & PRESSURE
COMPENSATED)
MEASUREMENT
PRESSURE TEMPERATURE FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH - PULL LEVER PEDALGENERAL MANUAL PUSH BUTTON SPRING
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVE ENVELOPES VALVE PORTS
FLUID CONDITIONERPUMP OR MOTOR
FLUID POWER SYMBOLS
UNIDIRECTIONAL
BIDIRECTIONAL
RELEASED PRESSURE
EXTERNAL RETURN INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED
HYDRAULIC PUMPS
ACCUMULATORS
SPRING LOADED GAS CHARGED
SOLENOID
OR MANUAL
SOLENOID
& PILOT
SOLENOID &
PILOT OR MANUAL
SOLENOID SERVO THERMAL DETENT
HYDRAULIC & PNEUMATIC CYLINDERS
DOUBLE ACTINGSINGLE ACTING
BASIC
SYMBOL
SPRING
LOADED
CHECK VALVES
2 POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW IN
EITHER
DIRECTION
3 POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
AB
PT
AB
PT
SHIFTED POSITION INFINITE POSITION
CONTROL VALVES
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
MAIN AUX
LINE RESTRICTION
(VARIABLE & PRESSURE
COMPENSATED)
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FLUID STORAGE RESERVOIRS
CROSSING & JOINING LINES
VALVES
PILOT CONTROL SYMBOLS
COMBINATION CONTROLS
BASIC COMPONENT SYMBOLS
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
INTERNAL
SUPPLY PRESSURE
COMPLETE
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
HYDRAULIC SYMBOLS (ELECTRICAL)
ELECTRICAL SYMBOLS TABLE
325-AG135 PK-14
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
WIRE
WIRE
(EXAMPLE VALVE)
CURRENT STANDARD
TRANSDUCER
(FLUID)
M
ELECTRIC MOTORTRANSDUCER
(GAS / AIR)
G
GENERATOR
PRESSURE SWITCH ELECTRICAL WIREPRESSURE SWITCH
(ADJUSTABLE)
TEMPERATURE
SWITCH
PRESSURE
SWITCH
TEMPERATURE
SWITCH
LEVEL
SWITCH
FLOW
SWITCH
ELECTRICAL SYMBOLS (ELECTRICAL)
A
CIRCUIT NUMBER
IDENTIFICATION
WIRE
COLOR
WIRE GAUGE
T
SENR6797-01
30 Page, (Dimensions: 39 inches x 28 inches)
Schematic
Description
Part
Number
for IT38G
Part
Number
for 938G
Machine
Location Location
Accumulator Atch 124-9439 124-9439 1 E-3
Accumulator Atch (Alternate Ride Control) 124-9439 124-9439 1 E-3
Accumulator Hydraulic 213-8773 213-8773 2 D-8 , D-7
Core As. (Hydraulic Oil Cooler) 135-5327 135-5327 3 C-4
Cylinder Gp - Lift 114-8131 128-7678 4 E-4
Cylinder Gp - Steering
105-0094,
139-3312
105-0094,
139-3312
5F-1
Cylinder Gp - Tilt 115-6963 9T-7161 6 F-4
Cylinder Gp (Coupler) 9T-8823 - 7 F-5
Filter Element 9J-5461 9J-5461 8 A-4
HMU (Hand Metering Unit) 113-0061 113-0061 9 D-1
Housing 101-2704 - 10 D-3
Manifold 9U-3862 9U-3862 10 E-3
Motot Gp (Fan Drive) 159-7986 159-7986 11 C-5
Pump Gp 105-2140 105-2140 12 B-7
Pump Gp - Piston (Hydraulic Fan) 139-6084 139-6084 13 B-5
Pump Gp - Supplemental Steering (Atch) 139-2327 123-8915 14 B-2
Tank Gp - Hydraulic 154-2140 160-3408 15 A-4
Valve - B
ypass (Hydraulic Oil Cooler) 130-5202 130-5202 3 C-4
Valve - Check (Pilot) 9T-3096 9T-3096 12 C-7
Valve - Check (Ride Control) 9T-3096 9T-3096 1 E-4
Valve Gp - Accumulator Charge 134-5106 134-5106 16 D-7
Valve Gp - Breaker Relief 9T-0818 9T-0818 15 B-4
Valve Gp - Diverter (Supplemental Steering) (Atch) 141-2597 141-2597 17 C-2
Valve Gp - Main Control 133-4240 133-4238
Valve Gp - Main Control (Atch) 133-4241 133-4239
Valve Gp - Main Implement Relief 108-6428 10
8-6428 19 E-6
Valve Gp - Manual Hydraulic Lockout 112-1817 112-1817 18 D-6
Valve Gp - Pilot 122-6346 122-6344
Valve Gp - Pilot (Atch) 122-6347 122-6239
Valve Gp - Relief 4T-2764 4T-2764 10 D-3
Valve Gp - Relief (Line)
122-6842,
105-7715
105-7715 19 E-4
Valve Gp - Relief (Line) (Coupler Cylinder) 105-7715 105-7715 19 E-5
Valve Gp - Relief (Line) (To fourth Function) 105-7715 - 20 E-6
Valve Gp - Relief (Line,Tilt Cyl Head End Port) 106-8528
106-8528 19 E-4
Valve Gp - Relief (Steering Backup) 6E-3447 6E-3447 21 E-2
Valve Gp - Relief Steering Control 9T-7420 9T-7420 21 E-1
Valve Gp - Relief Steering Crossover 9T-7419 9T-7419 21 E-1
Valve Gp - Selector And Press Cont (Pilot) 6E-3078 6E-3078 22 D-6
Valve Gp - Shutoff 6W-8221 - 7 E-5
Valve Gp - Solenoid 8T-8808 - 18 D-4 ,D-5
Valve Gp - Solenoid (Ride Control) (Atch) 149-2658 149-2658 1 E-3 , D-3
Valve Gp - Tandem Brake 215-3687 215-
3687 23 E-7
Valve Gp (Atch) (To Fourth Function) 6E-5958 6E-5958 20 E-6
18 E-4
19 C-4
Component Location
Valve Gp (Atch) (Coupler) 6E-5958 6E-5958 20 E-5
3
3
11
11
13
13
17
18
19 20
19 20
15
12
1421
1421
22
5
95
17
95
GG
12
22
GG JJ
BB
BB
HH
HH
JJ
4
4
2
16
39
67
67
8
110
101
Machine Harness Connector And Component Locations
Tap
Number
Description
Schematic
Location
GG
Steering Pump Pressure
C-8
JJ
Implement Pump Pressure
B-7
BB
Pilot Pump Pressure
D-6
HH
Hand Metering Unit Supply
C-1
Tap Locations
Pressure, Sampling, and Sensor
BRAKES
D
D
C
C
SECTION C-C
SECTION D-D
SENR6797-01
30 Page, (Dimensions: 39 inches x 28 inches)
Components are shown installed on a fully operable machine with the key and engine off, transmission shifter
in neutral and with parking brake set.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations.
SCHEMATIC PART NUMBER: 135-1807, CHANGE: 02, VERSION: -
PART NUMBER: 127-9648, CHANGE: 02, VERSION: -
PART NUMBER: 143-9472, CHANGE 02, VERSION -
-
MEDIA NUMBER: SENR6797-01
THIS SCHEMATIC IS FOR THE 938G WHEEL LOADER AND IT38G
INTEGRATED TOOLCARRIER HYDRAULIC SYSTEM
12345678
A
B
C
D
E
F
12345678
A
B
C
D
E
F
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
MAIN PUMP OUTPUT
SUPPLEMENTAL STEERING PUMP OUTPUT
STEERING CIRCUIT
SCAVENGE PUMP
SUPPLY LINE
BRAKE CIRCUIT
LIFT CIRCUIT
DRAIN / RETURN LINE
AUXILARY CIRCUIT
FOURTH FUNCTION CIRCUIT
TILT CIRCUIT
DUMP
C1
C2
T1
RAISE
LOWER
RACKBACK
CYLINDER GP
(STEERING)
139-3312
105-0094
VALVE GP
(STEERING
CONTROL)
9T-7420
RELIEF VALVE
(STEERING
CROSSOVER)
9T-7419
RELIEF
VALVE
(STEERING
BACKUP)
6E-3447
HMU
113-0061
PUMP GP
105-2140
CHECK
VALVE
9T-3096
DIVERTER
VALVE GP
(SUPPLEMENTAL
STEERING)
(ATCH)
141-2597
PUMP GP
(SUPPLEMENTAL
STEERING)
(ATCH)
123-8915
139-2327
HYD TANK GP
160-3408
154-9037
FILTER
ELEMENT
9J-5461
BREAKER
RELIEF
VALVE GP
9T-0818
PISTON
PUMP GP
(HYD FAN)
139-6084
CORE AS.
(HYD OIL
COOLER)
135-5327
BYPASS VALVE
(HYD OIL COOLER)
130-5202
MOTOR GP
(FAN DRIVE)
159-7986
CYLINDER GP
(AUX)
(ATCH)
CYLINDER GP
(TILT)
9T-7161
CYLINDER GP
(LIFT)
128-7678
114-8131
CHECK
VALVE
9T-3096
VALVE GP
6E-3078
VALVE GP
112-1817
124-9439
SOLENOID
VALVE
(RIDE CONTROL)
(ATCH)
149-2658
MAIN CONTROL
VALVE GP
133-4238
133-4240
(ATCH)
133-4239
133-4241
VALVE GP
(ATCH)
6E-5958
VALVE GP
(MAIN IMPL
RELIEF)
108-6428
RELIEF
VALVE
(LINE)
105-7715
122-6842
RELIEF
VALVE
(LINE)
106-8528
VALVE GP
(PILOT)
122-6344
122-6346
OSCILLATING REAR AXLE
FIXED FRONT AXLE
DUAL ACCUMULATOR
CHARGE VALVE
134-5106
LEFT AND RIGHT
PEDAL ASSEMBLY
NO
NC
C
HYDRAULIC
ACCUMULATOR
213-8773
HYDRAULIC
ACCUMULATOR
213-8773
TANDEM
BRAKE
VALVE
215-3687
TO XMISSON
CONTROL
TO STOP LAMP
SWITCH (NC)
BB
ACCUMULATOR
(ATCH)
TO AUDIBLE
AND VISUAL
SIGNLS SWITCH
IS NORMALLY
CLOSED
175-3244
BRAKES
HYDRAULIC COOLING
STEERING
JJ
GG
HH
(ATCH)
122-6239
122-6347
MANIFOLD
9U-3862
C3
RELIEF
VALVE
(LINE)
105-7715
RELIEF
VALVE
(LINE)
105-7715
VALVE GP
(ATCH)
6E-5958
TO FOURTH FUNCTION
CYLINDER GP
(AUX)
(ATCH)
VALVE GP
SHUTOFF
6W-8221
CYLINDER GP
(COUPLER)
9T-8823
RACKBACK
DUMP
C1
C2
T1
124-9439
SOLENOID
VALVE
(RIDE CONTROL)
(ATCH)
149-2658
ACCUMULATOR
(ATCH ALTERNATE
RIDE)
HOUSING
101-2704
C3
T2
T2
ALTERNATE RIDE CONTROL
VALVE GP
SOLENOID
149-2658
CYLINDER GP
(TILT)
115-6963
VALVE GP
RELIEF
4T-2764
VALVE GP
SOLENOID
8T-8808
VALVE GP
SOLENOID
8T-8808
IT38G ONLY
