RENR8879-05
November 2012
Hydraulic System
Printed in U.S.A.© 2012 Caterpillar, All Rights Reserved
950H, 962H, and IT62H Wheel Loader
950H:
N1A1-4396
JAD1-409
M1G1-2110
J5J1-UP
K5K1-2760
962H:
N4A1-2115
M3G1-678
J6J1-UP
K6K1-516
MAL1-122
IT62H:
M5G1-467
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
RENR8879-05
30 Page, (Dimensions: 39 inches x 28 inches)
QQ
48
RR
FF
1
The service center is located on the right side of the machine below the cab. The Following
components are located in the service center:
- Case drain filter (31)
- Hydraulic oil fluid sampling valve (SOS)
- Hydraulic systems kidney loop filter (28)
- Brake system accumulators (49)
The Following components are not referenced on the Hydraulic System Schematic:
- Power train oil fluid sampling valve (A)
- Power train oil filter (B)
- Ecology drain for the hydraulic tank (C)
The following remote pressure taps are located inside the panel on the frontside of the
service center:
- Steering pump outlet pressure (EE)
- Brake system accumulator pressure (PP)
The Following components are not referenced on the Hydraulic System Schematic:
- Transmission reverse clutch (A)
- Transmission forward clutch (B)
- Transmission fourth speed clutch (C)
- Transmission third speed clutch (D)
- Transmission second speed clutch (E)
- Transmission first speed clutch (F)
- Torque converter inlet pressure (G)
- Transmission lubrication pressure (H)
- Transmission pump outlet pressure (J)
- Torque converter outlet pressure (K)
- Steering cylinder rod end grease fittings (L)
- Rear axle oscillation bearing grease fittings (M)
The following components are located under the front of the cab.
- Hand metering unit (1)
- Foot service brake valve (48)
- Steer pump load sense test port (FF)
- Front sercive brake test port (QQ)
- Rear service brake test port (RR)
SERVICE CENTER
HMU AND SERVICE BRAKES
31
49
28
SOS
EE
PP
A
B
C
A
B
F
E
D
G
C
H
J
M
L
K
DD
CC
This photo shows a front view of the implement control valve (36) in the loader frame. The
following components can be seen in this view:
- Pilot accumulator (24)
- Pilot supply pressure tap (GG)
The Following components are not referenced on the Hydraulic System Schematic:
- Pressure differential relief valve (A)
- Head end solenoid valve (ride control) (B)
- Signal relief valve (C)
- Tilt anti-drift valve (D)
- Rod end solenoid valve (ride control) (E)
- Ride control balance solenoid valve (F)
- Pilot pressure reducing valve (G)
- Lift cylinder head end pressure tap (H)
- Lift cylinder head end pressure sensor for Payload Control System and Autodig (J)
- Hydraulic lockout solenoid valve (K)
This photo shows a left rear view of the implement control valve (36). The following components can
be seen in this view:
- Implement control valve supply pressure tap (GG)
The Following components are not referenced on the Hydraulic System Schematic:
- Tilt anti-drift valve (A)
- Signal relief valve (B)
- Signal duplication valve (C)
- Return to tank port (D)
- Supply port from pump (E)
- Signal line to pump (F)
- Tank line (G)
- Screen (H)
- Tilt back pilot solenoid valve (J)
- Tilt back pilot (K)
- Tilt cylinder rod end line relief (L)
- Ride control balance solenoid valve (M)
- Rod end solenoid valve (ride control) (N)
IMPLEMENT CONTROL VALVE
This drawing shows a right side view of the wheel loader. The following components can be seen
in this view:
- Implement pump pressure tap (CC)
- Implement pump load Sense pressure tap (DD)
24
GG
CC
A
B
F
E
D
G
H
J
K
C
C
A
B
F
E
D
G
H
J
K
L
M
N
BOTTOM VIEW
RIGHT SIDE MACHINE VIEW
COMMAND CONTROL STEERING
MM
NN
KK
LL
10
6
12
Tap Locations
Pressure, Sampling, and Sensor
Tap
Number
Description
Schematic
Location
AA Fan Pump Discharge Pressure B-8
E-9
CC Implement Pump Charge Pressure E-9
DD Implement Pump Load Sense Pressure B-7
EE Steer Pump Pressure B-7
FF Steer Pump Load Sense Pressure A-4
or C-4
GG Pilot Supply Pressure E-5
HH Fan Pump Load Sense Pressure B-8
KK Command Control Right Steer Pilot Pressure D-2
LL Command Control Left Steer Pilot Pressure D-2
MM Command Control Steering Neutral Pilot Press D-3
NN Command Control Steering Supply Pressure D-3
PP Service Brake Pressure F-3
QQ Front Service Brake Pressure F-4
RR Rear Service Brake Pressure F-4
XX Tilt Cylinder Rod End Pressure F-8
YY Tilt Cylinder H
ead End Pressure F-8
SOS Hydraulic Oil Sampling Port B-9
Item
Number
Description
Part
Number
Schematic
Location
1 Hand Metering Unit 230-4176 A-4
2 Connector - Orifice 122-2340 B-3 , B-4
3 Cylinder Gp - Steer 163-0324 B-1
4 Valve Gp - Neutralizer 146-7571 B-3 , B-4
5 Valve Gp - Steer 142-4000 B-2
6 Valve Gp - Neutralizer 8J-1553 D-3
7 Valve Gp - Steer 124-8635 D-1
8 Cylinder Gp - Steer 163-0324 E-1
9 Valve Gp - Check 111-7775 D-3
10 Valve Gp - Pilot 147-1790 D-4
11 Valve Gp - Shuttle 8J-6875 C-3
12 Screen Gp 154-2883 E-2
13 Pump Gp - Steering 241-9299 A-6
14 Pump Gp - Implement 254-4108 A-7
Cylinder - Tilt 242-4220 F-8
Cylinder - Tilt (Mid Lift) 247-0497 F-8
Cylinder - Tilt (High Lift) 245-7491 F-8
Cylinder - Tilt (Logger) 245-7487 F-8
20 Cylinder - Lift (LH) 242-4272 F-7
21 Cylinder - Lift (RH) 242-4271 F-7
22 Valve - Choke Check 276-9072 D-9
23 Valve Gp - Manual Lowering 112-1817
E-9
24 Accumulator - Pilot Oil 245-2975 F-5
25 Pump Gp - Fan 254-5146 B-8
26 Motor Gp - Fan 246-6152 D-6
27 Valve Gp - Cooler Bypass 244-1426 B-9
28 Filter Gp - Return Oil 244-1031 B-9
30 Manifold Gp - Fan & Brake Charge 242-1307 C-8
31 Filter Gp - Case Drain 249-2334 A-8
32 Valve Gp - Breaker Relief 220-0814 A-8
33 Tank Gp - Hydraulic Oil 237-2742 A-8
34 Valve Gp - Secondary Steer Diverter 141-2597 B-6
35 Pump Gp - Secondary Steer 275-8544 A-6
Valve Gp - Control
(2 Function Standard)
261-4171 D-9
Valve Gp - Control
(2 Function W/RC)
261-3682 D-9
Valve Gp - Control
(3 Function)
261-4172 D-9
Valve Gp - Control
(2 Function W/RC)
261-3683 D-9
Valve Gp - Control (Snow Removal)
(3 Function W/RC)
274-8055 D-9
41 Accumulator - Ride Control (RC) 245-2973 F-6
42 Valve Gp - Control & Relief 263-5832 C-7
43 Motor Gp - Reversing Fan 228-8527 C-6
25 Pump Gp - Fan 254-5146 F-2
30 Ma
nifold Gp - Fan & Brake Charge 242-1307 F-2
45 Control Gp - Foot Brake 193-1448 F-3
46 Switch As - Foot Brake Limit 105-6117 F-3
47 Sensor Gp - Foot Brake 214-4863 F-3
48 Valve Gp - Foot Brake 215-3687 F-3
49 Accumulator - Service Brake 213-8773 F-2
50 Actuator As - Parking Brake 129-8090 F-1
51 Valve Gp - Parking Brake 106-1774 F-2
52 Switch As - Parking Brake Pressure 174-4312 F-1
53 Switch As - Brake Pressure 175-3244 F-3
Component Locations
36
15
HMU STEERING CIRCUIT
COMMAND CONTROL STEERING
MAIN SCHEMATIC
BRAKE SYSTEM
54 Valve Gp - Quick Coupler 180-8585 C-9
55 Cylinder Gp - Quick Coupler 237-0946 C-9
56 Valve Gp - Manual 112-1817 C-9
MACHINE COMPONENT LOCATIONS
FRONT VIEW
REAR VIEW
3
8
23
20
1
15
27
26
43
3233
42
3
8
5
11
24
7
12
36
10
22
41
2
4
6
2
4
6
9
21
45
47
46
48
28
31
49
34
35
25
53
30 13
14
50
52
51 5
12
28
7
23
31
50
51
52
3
8
49
13
14
25
30
53
34
35
42
2
4
6
910
11
22
36
24
41
26 43
27
32 33
1
45
47
46
48
20
21 15
TILT CYLINDER LINES GROUP
VIEW A - A
RIGHT SIDE VIEW
YYXX
YYXX
15
15
FAN AND BRAKE HYDRAULIC SYSTEM
The fan and brake pump (25) is located on the front gear train of the engine, on the right side of the
machine. The fan and brake pump provides oil flow for the electronic demand fan systemand the
brake hydraulic system. The outlet pressure tap (AA) is located on the fan and brake pump.
Also located on the engine on the right side of the machine is the fan control and brake accumulator
charging valve (30). The fan pump load sense pressure tap (HH) is located above the brake charging
valve.
FAN AND BRAKE PUMP
25
30
HH
AA
RENR8879-05
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: 241-0475, CHANGE: 09, VERSION: -
MEDIA NUMBER: RENR8879-05
THIS SCHEMATIC IS FOR THE HYDRAULIC SYSTEM
BRAKE SYSTEM PART NUMBER: 244-1398, CHANGE: 00, VERSION: -
950H, 962H, AND IT62H WHEEL LOADER
2
3
4
56
7
8
2
3
4
56
7
8
11
9
A
C
D
E
F
B
C
D
E
F
B
23
4
56
7
8
23
4
56
7
8
1
9
A
B
C
D
E
F
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)
YY
DRAIN / RETURN LINE
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
IMPLEMENT PUMP OUTPUT
PRIMARY STEERING PUMP CIRCUIT
STEERING CIRCUIT
IMPLEMENT PILOT SUPPLY OIL
AUXILIARY CIRCUIT
IMPLEMENT PUMP LOAD SENSING CIRCUIT
SUPPLY LINE
TILT CYLINDER CIRCUIT
LIFT CYLINDER CIRCUIT
SECONDARY STEERING CIRCUIT
BRAKE CHARGE VALVE AND FAN CONTROL CIRCUIT
MAIN RELIEF VALVE LOAD SENSING CIRCUIT
BRAKE CONTROL CIRCUIT
EE
AA
SOS
HH
DD
FF
MM
NN
LL
KK
FF
GG
XX
YY
CC
RR
QQ
PP
HMU STEER AND 3PC IMPLEMENT
COMMAND CONTROL STEERING ATTACHMENT
a1
a1
b1
b1
c1
c1
c1
d1
d1
d1
e1
e1
e1
CROSSOVER
RELIEF
SHUTTLE VLV
DIRECTIONAL SPOOL
MAKE UP
CHECK
BACK UP
RELIEF
PRESSURE
REDUCING
VALVE
PILOT PORT"A"
PILOT PORT"B"
REGULATED
PRESS. PORT
TO PILOT VALVE
TANK PORT
CYL PORT "A"
CYL PORT "B"
LOAD SENSING
PUMP PORT
Port A Lever Forward
Left Hand Line on Boom
(When Viewed From Cab)
CROSSOVER RELIEF
CYL PORT "A"
CYL PORT "B"
MAKE-UP CHECKS
DIRECTIONAL SPOOL
BACK-UP RELIEF
PUMP PORT
HMU SUPPLY PORT
PILOT PORT "B"
PILOT PORT "A"
PILOT CONTROL SPOOL
TILT
RACK
BACK
DUMP
RACK
BACK
HOLD
DUMP
LIFT
RAISE
LOWER/
FLOAT
RAISE
HOLD
LOWER
FLOAT
HOLD
HEAD
END
PORT
“B”
3RD FUNCTION
(ATTACHMENT)
PORT
A
PORT
B
LS DR
R
H
LS
P
T
F
PS
A1
A2
TO FRONT
BRAKES
TO REAR
BRAKES
BRAKE SYSTEM
A1
A2
PS
F
LS
P
T
To Fan Motor
To
Case Drain
Manifold
NC
NO
C
C
TO TRANSMISSION
CONTROL
TO BRAKE
LIGHTS
APPLY
RELEASE
FRONT AXLE
REAR AXLE
HYDRAULIC
TANK
Connection b1 only for Command Control Steering
Port B Lever Rearward
Right Hand Line on Boom
(When Viewed From Cab)
QUICK COUPLER (ATTACHMENT)
(1) Hand Metering Unit:
230-4176
(4) Valve Gp - Neutralizer:
146-7571
(2) Connector -
Orifice: 122-2340
(5) Valve Gp - Steer:
142-4000
(3) Cylinder Gp -
Steer: 230-4176
(11) Valve Gp - Shuttle:
8J-6875
(9) Valve Gp - Check:
111-7775
(6) Valve Gp -
Neutralizer: 8J-1553
(10) Valve Gp - Pilot:
147-1790
(12) Screen Gp:
154-2883
(8) Cylinder Gp - Steer:
163-0324
(7) Valve Gp - Steer:
124-8635
(48) Valve Gp - Foot Brake:
215-3687
(30) Manifold Gp -
Fan and Brake Charge: 242-1307
(25) Pump Gp - Fan:
254-5146
(52) Switch As -
Parking Brake Pressure:
174-4312
(50) Actuator As. -
Parking Brake:
129-8090
(51) Valve Gp - Parking Brake:
106-1774
(49) Accumulator - Service Brake:
213-8773
(45) Control Gp - Foot Brake:
193-1448
(46) Switch As. - Foot Brake Limit:
105-6117
(53) Switch As. - Brake Pressure:
175-3244
(47) Sensor Gp - Foot Brake:
214-4863
(31) Filter Gp -
Case Drain:
249-2334
(32) Valve Gp -
Breaker Relief:
220-0814
(28) Filter Gp - Return Oil:
244-1031
(27) Valve Gp -
Cooler Bypass:
244-1426
(34) Valve Gp - Secondary Steer Diverter:
141-2597
(26) Motor Gp -
Fan: 246-6152
(54) Valve Gp -
Quick Coupler:
180-8585
(56) Valve Gp -
Manual: 112-1817
(55) Cylinder Gp - Quick Coupler:
237-0946
(30) Manifold Gp -
Fan and Brake Charge:
242-1307
(25) Pump Gp - Fan:
254-5146
(36) Valve Gp - Control:
2 Function Standard: 261-4171
2 Function W/RC: 261-3682
2 Function W/RC: 261-3683
3 Function Standard: 261-4172
3 Function W/RC: 274-8055
(23) Valve Gp - Manual Lowering:
112-1817
(15) Cylinder Gp -
Tilt: 242-4220
Tilt (Mid Lift): 247-0497
Tilt (High Lift): 245-7491
Tilt (Logger): 245-7487
(21) Cylinder - Lift (RH)
242-4271
(41) Accumulator - Ride Control (RC):
245-2973
(20) Cylinder - Lift (LH):
242-4272
(24) Accumulator - Pilot Oil:
245-2975
(14) Pump Gp - Implement:
254-4108
(13) Pump Gp - Steering:
241-9299
(35) Pump Gp - Secondary Steer:
275-8544
(33) Tank Gp - Hydraulic Oil:
237-2742
Relief:
272-7003
256-2866
Relief:
272-7003
Relief:
247-8632
Relief:
254-5789
Relief:
282-4349
Relief:
4T-7581
Relief:
272-2334
Relief:
272-2334
