RENR6262-02
June 2011
990 and 990 Series II Wheel Loader
Hydraulic System
Printed in U.S.A.© 2011 Caterpillar, All Rights Reserved
7HK1-UP
4FR1-UP
BCR1-UP
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
RENR6262-02
30 Page, (Dimensions: 39 inches x 28 inches)
Pilot Pressure
LINEAR PATTERNS
Return Lines
Pressure
Components
Denotes Wire Code
Parts Manual
Systems
Power Train
Systems Operation
Testing and Adjusting
Systems Operation (Steering)
Specification (Braking)
Specifications (Machine Systems)
System Operation (Braking)
Testing and Adjusting (Braking)
Specifications
Specifications (Steering)
Media
Number
Electrical System
SEBP3340
RENR6250
RENR6251
RENR6252
Disassembly and Assembly Supplement
RENR6264
RENR6253
RENR6254
RENR6255
RENR6256
RENR6257
RENR6258
RENR6259
RENR6260
RENR6261
RENR6045
RENR6262
Schematic
RENR6263
990 SERIES II (BCR) MEDIA REFERENCES
Parts Book
Systems Operation (Hydraulics)
Specifications (Hydraulics)
Testing and Adjusting (Hydraulics)
System Schematic (Hydraulics)
Testing and Adjusting (Steering)
Location
Part No.
Chart B
Tap
BB
AA
CC
DD
6V-3965
6V-3965
Description
Steering Pump Cutoff
D4
Fluid Sampling Port
D6
Hydraulic Fan Pump Cutoff
E7
6V-3965
Pilot Supply (Steering)
F3
Pressure Tap and Sampling Port Locations
8C-3446
Item Part No. Serial No. Description Location
1 6E-1244 7HK, 4FR, BCR Steering Cylinder (Left) A1
2 9T-9568 7HK, 4FR, BCR Steering Cylinder (Right) A2
3a 6E-2925 7HK, 4FR, BCR Steering Valve (Standard) A3
3b 6E-2923 7HK, 4FR, BCR Steering Valve (With Secondary Steering) A3
4 6E-3985 7HK, 4FR, BCR Relief Valve (Steering Cylinder Crossover) A1
5 4T-1860 7HK, 4FR, BCR Valve (Shuttle) A3
6 7J-7423 7HK, 4FR, BCR Check Valve (Secondary Steering Pump) A5
7 2U-7345 7HK, 4FR, BCR Diverter Valve (Secondary Steering) A5
8 4B-9782 7HK, 4FR, BCR Ball (Steering Cylinder Makeup Valve) B2
9 6E-3780 7HK, 4FR, BCR Valve (Primary Steering Pump Check) B4
10 6E-3776 7HK, 4FR, BCR Stem (Steering Valve) B1
11 100-4335 7HK, 4FR, BCR Relief Valve (Pump Backup) B3
12 6E-3986 7HK, 4FR, BCR Relief Valve (Secondary Steering) C5
13 176-9369 7HK, 4FR, BCR Check Valve (Steering) C2
14 6E-4286 7HK, 4FR, BCR Pressure Reducing Valve (Steering) C4
15 101-4007 7HK, 4FR, BCR Secondary Steering Pump C4
16 159-7166 7HK, 4FR, BCR Piston Motor (Hydraulic Fan) D4
193-0629 BCR
101-9012 7HK, 4FR
18 4T-4207 7HK, 4FR, BCR Cushion Orifice (1.2mm) D2
19 176-9371 7HK, 4FR, BCR Check Valve (Steering) D2
20 9T-7426 7HK, 4FR, BCR Steering Neutralizer Valve (Right) D1
21 9T-7426 7HK, 4FR, BCR Steering Neutralizer Valve (Left) D2
22 6E-5566 7HK, 4FR, BCR Selelector and Pressure Control Valve D3
23 148-8978 7HK, 4FR, BCR Hydraulic Oil Cooler (Hydraulic Fan) D6
24 6E-1454 7HK, 4FR, BCR Check Valve (Hydraulic Oil Cooler Bypass) D6
25 3E-6450 7HK, 4FR, BCR Pressure Switch (Primary Steering Oil) E3
196-6098 BCR
6E-1542 7HK, 4FR
194-6800 BCR
109-4197 7HK, 4FR
196-7765 BCR
6E-4469 7HK, 4FR
28 143-2855 7HK, 4FR, BCR Pilot Valve E2
29 6E-5566 7HK, 4FR, BCR Selector and Pressure Control Valve E3
30 104-7108 7HK, 4FR, BCR Check Valve E4
31 6E-3528 7HK, 4FR, BCR Breaker Relief Valve F6
32 6E-4683 7HK, 4FR, BCR Hydraulic Tank F6
33 152-7202 7HK, 4FR, BCR Thermostatic Valve F7
34 4T-3134 7HK, 4FR, BCR Filter F6
35 6E-4679 7HK, 4FR Fan Control Valve
36 6E-4680 7HK, 4FR Pressure Reducing Valve
37 3E-8574 7HK, 4FR Solenoid Valve
27b Piston Pump (High Ambient Hydraulic Fan) E6
Steering and Fan System
Piston Pump (Steering) E426
Piston Pump (Standard Hydraulic Fan) E627a
Makeup Check Valve (Hydraulic Fan) C617
20 2813
131
3
15
33
26 23 16
45678910
11 12 14 18 22 25 29
322
21 19 27 24 17
30
ENERGIZE TO REDUCE
FAN SPEED AND POWER
A
B
C
D
E
F
1
2
3
45
6
7
A
B
C
D
E
F
G
765
4321
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
18
19
20
21
22
23
24
25
27
28
30
31
32
16
17
HYDRAULIC STEERING AND FAN SYSTEM SCHEMATIC
G
26
33
(201-BK)
(417-GY)
STOP
STOP
29
37
35
36
34
DD
AA
BB
CC
RENR6262-02
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.
MEDIA NUMBER: RENR6262-02
THIS SCHEMATIC IS FOR THE 990 AND 990 SERIES II WHEEL LOADER
HYDRAULIC SYSTEM
Pilot Pressure
LINEAR PATTERNS
Return Lines
Pressure
Components
Denotes Wire Code
Item Part No. Serial No. Description Location
1 101-7034 7HK, 4FR, BCR Actuator (Parking Brake) A2
2 101-7034 7HK, 4FR, BCR Valve (Parking Brake) A2
3 N/A 7HK, 4FR, BCR Valve (On/Off Manual) A3
4 171-7085 7HK, 4FR, BCR Switch (Parking Brake) A3
5 177-4104 7HK, 4FR, BCR Pilot Valve A4
6 108-0221 7HK, 4FR, BCR Pilot Valve (Tilt) A5
7 108-0222 7HK, 4FR, BCR Pilot Valve (Lift) A5
8 145-9897 7HK, 4FR, BCR Tilt Cylinder A7
9 9T-9569 7HK, 4FR, BCR Lift cylinders A8
10 N/A 7HK, 4FR, BCR Shuttle valve (Parking Brake Valve) A4
11 116-3045 7HK, 4FR, BCR Orifice (Pilot Valve Cartridge) A4-A6
12 116-3045 7HK, 4FR, BCR Check Valve (Dead Engine Lower) B8
13 6E-3078 7HK, 4FR, BCR Selector and Pressure Control Valve B8
14 4F-1860 7HK, 4FR, BCR Shuttle Valve (Ball Resolver) B8
15 112-2273 7HK, 4FR, BCR Foot Pedal (Service Brakes) B1
16 174-4312 7HK, 4FR, BCR Pressure Switch (Parking Brake Oil) B3
17 164-5633 7HK, 4FR, BCR Adapter Assembly (Orifice 1.6mm) B5
18 196-3821 7HK, 4FR, BCR Main Control Valve B6
19 129-7673 7HK, 4FR, BCR Valve (Service Brake Control) C1
20 100-4866 7HK, 4FR, BCR Track Stem C6
21 9U-2856 7HK, 4FR, BCR Service Brakes (Front) D3
22 100-4866 7HK, 4FR, BCR Stem (Tilt) D6
23 102-4156 7HK, 4FR, BCR Check Valve (Load) D6
24 6E-3185 7HK, 4FR, BCR Line Relief Valve (Dump) D7
25 9T-9552 7HK, 4FR, BCR Diverter Valve (Ride Contol) D9
26 6E-3303 7HK, 4FR, BCR Stem (Diverter Valve Ride Control) D9
27 6E-4185 7HK, 4FR, BCR Accumulators (Ride Control) D10
28 9D-2632 7HK, 4FR, BCR Accumulator (Pilot) D4
29 9T-9551 7HK, 4FR, BCR Combination Valve (Parking) E5
30 102-4156 7HK, 4FR, BCR Check Valve (Load) D6
31 9T-6720 7HK, 4FR, BCR Line Relief Valve (Tilt Back) D6
32 100-7001 7HK, 4FR, BCR Valve (Check/Flow Control) E8
33 142-4281 7HK, 4FR, BCR Line Relief Valve (Raise) E4
34 158-9956 7HK, 4FR, BCR Check Valve E4
35 6R-0442 7HK, 4FR, BCR Shuttle Valve E4
36 6E-6293 7HK, 4FR, BCR Relief Valve (Pilot) E5
37 117-7761 7HK, 4FR, BCR Unloading Valve (Pilot) E5
38 152-8340 7HK, 4FR, BCR Solenoid Valve (Ride Contol) E9
39 100-6731 7HK, 4FR, BCR Stem (Float Valve) F5
40 100-4867 7HK, 4FR, BCR Stem (Raise) E6
41 6E-1291 7HK, 4FR, BCR Valve (Pilot Operated Check) E6
42 196-3822 7HK, 4FR, BCR Main Relief Valve E7
43 4Z-6240 7HK, 4FR, BCR Relief Valve (Main) F7
44 6E-5842 7HK, 4FR, BCR Check Valve (Main Relief) F8
45 9U-2856 7HK, 4FR, BCR Service Brakes (Rear) E2
46 148-8977 7HK, 4FR, BCR Hydraulic Oil Cooler F7
47 6E-3528 7HK, 4FR, BCR Breaker Relief Valve F7
48 100-6909 7HK, 4FR, BCR Accumulators (Service Brakes) F4
49 158-9956 7HK, 4FR, BCR Check Valves F5
50 108-1176 7HK, 4FR, BCR Plug (Orifice) F5
51 116-6399 7HK, 4FR, BCR Relief Valve (Service Brake Backup) F5
52 9T-9554 7HK, 4FR, BCR Hydraulic Tank F7-G7
53 6E-4657 7HK, 4FR, BCR Pump (Pilot/Braking) G5
54 6E-3321 7HK, 4FR, BCR Piston Pump (Implement) C2
Braking and Implement System
Location
Part No.
Tap
BB
AA
CC
DD
EE
FF
GG
HH
II
JJ
KK
6V-3965
6V-3965
6V-3965
6V-3965
6V-3965
6V-3965
6V-3965
Description
Pressure Tap and Fluid Sampling Port Locations
6V-3965
LL
Head End (Lift Cylinder) B9
Rod End (Lift Cylinder)
C9
6V-3965
Head End (Tilt Cylinder)
Rod End (Tilt Cylinder)
C7
C7
Service Brakes (Front)
D2
Pilot Oil (Implement)
6V-3965
E4
6V-3965
Pilot Oil (Ride Control)
E9
8C-3446
Fluid Sampling Port
E4
Service Brakes (Rear)
E2
Parking Brake Oil
E4
Main Relief Valve (Implement)
Main Relief Valve (Implement)
F9
F9
28
5
48
12
8
21
4227 914645
4752 4443
14
2625
13
35
484950
2934
36
3751
171176
38
53
2
18
15
54
19
34
1016
24232220
33323130 414039
AA
BB
CCDD
BRAKING SYSTEM
A
B
C
D
E
F
G
1
2
3
45
6
7
A
B
C
D
E
F
G
765
4321
8910
8
910
II
IMPLEMENT AND BRAKING SYSTEM SCHEMATIC
1
2
3
4
7
6
8
9
12
13
14
15
17
18
19
20
21
16
22
23
24
27
28
29
30
31
32
11
11
33
10
5
34
35
36
37
38
39
47
41
42
43
44
45
46
48
49
50
51
52
53
54
40
(201-BK)
(C491-PU)
(G756-YL)
(419-YL)
(G764-PK)
(202-BK)
(202-BK)
(102-RD)
(604-OR)
(E799-BR)
(F701-BR)
25
26
CC
DD
AA
BB
GG
KK
LL
FF
HH
JJ
EE
