RENR6219 July 2005
Component Locations Part Number Steering and BrakeSystem
I et m
De sc ir pt oi n
1
Schematic Location
TANK AS .
152-3870
B3
2
TANK GP
153 -360 2
B3
3
SCREEN AS.
9T-9227
B2,B3
7J-2656
B2,B3
4
SCREEN GP GP
5
SCREEN
6
TUBE-BAFFLE
1U-1570
7
VALVE G P-PILOT
143-2855
B4
178-0182
B2
ACCUMUL A TOR GP
220-1432
F2,F3
COOLER
164-0058
C2
1 0
V A L VE G PC - OO LE RB YP AS S VALVE GP-B RAKE
12
FILTER GP
13
P UM P GP -S UP PL EM EN T A L ST ER
14
6 E- 14 54
VALVE GP- STER
1 50 -7 58 5
D4
9T-7419
D4
PLUG-ORIFICE
1T-0936
D4
6 E- 42 86
20
VALV E G P-RELIEF VALV E G P-DIV E RTER
2U-7345
D3
22
CYLINGER GP- R IGHT
135-3288
E4
CYLINGER GP-LEFT VALV E GP GP-CHE CK
2 5
V A L VE G P- NE U T RA LI Z E R
6E-3986
D3
133-8173
E4
149-4617
C4
1 46 7 - 57 1
PUMP G P -STEER
27
VALVE GP-COMP
176-7520
28
VALVE GP-COMP
176-7521
C 4
153 -962 4
C3
189-8628
C1
VA LVE GP
186 -621 8
C2
32
VALV EGP-RELIEF VA V L E- FL U ID SA M P L IN G VALV E GP-CHE CK
35
FILTER VALV E GP-SEL E CTOR MOTOR GP-PISTON
38
VALV E GP-CHE CK
39
139-3544
41
C1
VALVE-CHECK
C3
9T-3752
C1
C4
104-7108
B 2
220-0812 2 2 0 2- 9 4 8
S WI TC HA S. -P RE SS UR E
1 75 -3 24 4
E2
VALVE GP
200-0866
F3
47
C ON TR OL G P- FO OT B RA KE
B 2
F3
1 69 -8 25 8
VALVEG P-B R AKE
106-1774
S WI TC HA S. -P RE SS UR E
1 74 -4 31 2
85
2
C4
133-1963
TA N K GP E - X PA N SO I N
45
48
91
B1
46
49
g a P 6 3
45
B1
9 T- 3 0 9 6
VALVE-CHECK VA L V EG P- B RE A K ER & R E L EI F
4 4
29
B1
C2
207-0695
43
BXY1-UP 11
B2
6E-5566 213-5268
228-3638
42
988H Wheel Loader Hydraulic System
C2
8 C - 3 4 4 6 3G-8607
VALVE GP-COMP
The brake/pilot pump (29) ismounted to the righ t rear side of the pump drive. The brake/pilot pump supplies oilflow to the brake hydraulic system and pilot oilto the steering hydraulic system and the implement hydraulic system.
B 1
228-3636
PUMPGP-FAN
40
1 7 8- 9 2 4
166-4647
36 37
The ride controlsolenoid (79) is located in the front frame behind and above the front axle housing. The ride control solenoid is an ON/OFF solenoid. When the ride controlsolenoid is energized the head end of the lift cylinders are connected to the ride controlaccumulator to absorb the shock that occurs when roading the machine. The ride controlsolenoid is a part of the ride controlvalve group (78).
C3
P U M PG P - B R A K E / P IL O T VALVE GP
3 3
The accumulator charging valve (11) is located on the right side of the machine between the hydraulic tank(2) and the rear frame. The brake pressure switch (45) sends a signalto the Caterpillar Monitoring System.
The ride controlaccumulator (85) ismounted horizontally along the inside of the front right side of the frame, to the rear of the front axle housing.
29. Brake/pilot pump 91. Axle cooling pumps
F2 F1
5 0
B R A K EG P - P A R KB -
1 7 4 1- 5 2
F1
5 1
S E NS O R GP T- E M P
1 3 1 0- 4 2 7
F4,E4
BRAKE/PILOTPUMP
HYDRAULIC TANK ASSEMBLY
Implement System
RIDE CONTROL
212-8712 52
V ALVE-G P-CONTROL
9 1 2 6 R o i s N n e m E i D ( R , e
29 F
8. Front brake accumulator 8. Rear brake accumulator 2. Hydraulic tank 32. Pilot relief valve 12. Pilot filter 43. Vacuum breaker relief valve F. Pilot pressure tap K. Rear Accumulator Pressure tap J. Front Accumulator Pressure tap 33. S.O.Stap
C3
2 9 30 31
34
2
D 4
21
23
79
D4
V A L VE G P- PR ES S RE DU C I N G VALV E G P-RELIEF
19
24
8
8
D3
4T-1860 6E-6188
1 7 18
26
) s e h c n i 5 3 x s e h c n i 8 4 : s n
78
C3
133-8609
VALV EGP-SHUTTLE VALV E G P-RELIEF
32
E2 C2
133-8608
15
J 12
C 2
133-7102 115-2129
16
33 K
B2
8 9 11
43
212-8746
© 2007 Caterpillar, All Rights Reserved
D8
Printed n i U.S.A.
212-8721 5 3
V A L VE GP P - RE SS UR EC ON T
6 E- 42 86
D 8
54
VALV EG P -SHUTTLE
4 T1 8 6 0
D8
55
VALV EGP-RELIEF
125-9349
D7
56
VALV EGP-RELIEF
117-0161
D8
57
VALV EGP-RELIEF
58
VALV EGP-RELIEF
59
VALVE GP-RELIEF
60
117-0161
D7
117-0160
D7
117-0159
C6
143-8912
ACTUATOR GP
2 1 7 -6 7 1 9
61
VALV E-FLOAT
1 0 0 -6 7 3 1
C8
62
VALVE
6E-1291
C7 C8
63
ACTUATOR GP
2 1 7 -6 7 2 0
D7
102-4156
C6,C7
64
VALVE
65
VALV EGP-RELIEF
172-5481
D7
CYL GP-LIFT
173-8613
E8
66 A 6 6 B
CY LG P - L I T F (L O G G E R )
67 A
CYL GP-TILT CY LG P - T I T L (L O G G E R ) C Y L GP T - LI T ( HI G H LI F T )
68 A
1 6 8 6- 9 4 3
CYL GP-LIFT CY LG PL FI (T L O GG E R)
6 9
P U M PG P- M I P LE M E N T
70
IMPELLER
71
COIL AS.
30
39 I
10
35
76 12
29 82
89
69 81
26 G
H
36
88 87
K
14 41
44 86
24 49 33
J
73 74 7
43
48 90
46 L M
47
67
2223
B C D E 52 72
FLUID POWER SYMBOLS
66 68
83 84
BASICCOMPONENT SYMBOLS
PUMPorMOTOR
FLUIDCONDITI ONER
VARIABILITY
SPRING (ADJUSTABLE)
E 7 E 7 E6
1 6 8 6- 9 4 2
B 7
146-8990
B7
148-2350
B7
9T-3096
D8
ONEO P STI I O N
VALV E GP-CHE CK VALV E GP-CHE CK VA V LE G P -SOL E NOID
75
VALVE GP-SOLENOID
104-7108
B8
151 7- 45 5
B8
1 4 9 -2 6 1 0
76
FILTER
77
VALV EG P-BALL
112-1817
78
VA LVE GP
9T-9 552
79
VALVE GP-SOLENOID
80
ORIFICE
81
TW O P O ISTOI N
THR EEP O STI I O N
1 5 2 -8 3 4 0
V E N T E D
C6
204-7143
B7
SENSO R GP
143-9176
B7
VALV EGP-SHUTTLE
141-1481
B5
VALV E GP-CHE CK
207-1810
B5
85
ACCUMUL ATOR
219-7983
D5
FOUR-WAY
THREE-WAY
CHECK VALVES
SPRING LOADED
BASIC SYMBOL
S H U T E L
R ET U R N B A O V E LF UI D L E V E L
P R E SS U RZ I E D
P LI O T CONTROLLED
R ET U R N E B LO WF L UD I L E V E L
MEASUREMENT
C6
8J-6815
ADAP TER
84
TWO-WAY
INFIN ITEPO SITIN O
FLUIDSTORA GE RESERVOIRS The service brake valve (46) is located belowthe right brake pedal. The left and right brake pedals are mechanically connected, allowing the service brake valve to be actuated by either brake pedal. Also, front service brake oil pressure can be checked at the front service brake pressure tap (L) and rear service brake oil pressure can be checked at the rear service brake pressure tap (M).
B8 C6
82
ATTACHMENT
VALVEPORTS
AB
PT S H I FE TD P O STI I O N
PT NORMALPOSITION
B6
83
LINERESTRICTIO N VARIABLEand PRESSURE COMPENSATED
VALVES
B8
166-4647
MAINAUX. PUMP: VARIABLEand 2-SECTIONPUMP PRESSURECOMPENSA TED
L I N EERS T R CIT I N O (FIXED)
HYDRAULIC PNEUMATIC ENERGYTRIANGL ES
CONTROL VALVES AB
72 73 7 4
R E SR T I CITO N
PRESSURE COMPENSATION
LINERESTRICTI ON (VARIABLE)
VALVE ENVELOPES
L
E 6
2 1 6 8 - 9 7 8
CONTROLVALVE S
SPRING
M
46
E7
1 9 1 3- 4 6 8 1 52 1 - 64 4 173-8612
6 8 B
9
E 8
231-1955
6 7 B 6 7C
37 38
PR S E U S R E
ROTATING SHAFTS
TEM E PR TA R U E
FL W O
U N I D I R EC IT O N LA
B DI RI C E IT N O L A
COMBINATION CONTROLS
AxleCool ing System 86
MOTOR GP - A FN
178-1602
F8
87
CORE AS.
1 7 3 -6 7 5 3
F7
88
VALVE-CHECK
9 T- 5 1 3 4
F8
89
VALVE GP -S -SOLENOID
1 4 9 -2 6 1 0
F8
90
FILTER GP-SCREEN
230-3633
F7
91
PUMP GP
229-0659
F6
92
PUMP GP
260-3160
F8
SOLENOID
SOLENOID or MANUAL
SOLENOID andPILOT
S R E O V
SOLENOIDand PILOTorMANUAL
TH R E M A L
D TEE N T
MANUAL CONTROL SYMBOLS
Service Brake
PUSH- PULL LEVER
MANUALSHUTOFF
GENERAL M ANUAL
EXTERNALRETURN
PUSH U B TTON
PILOT CONTROL SYMBOLS
RELEASEDPRESSURE
Note:Relatedcomponentsare sectionedandcalled outbybold partsonly(item2 includesnumbers3,4, 5,and6) seperatedbyblanklines. Itemswithnogroup are listedindividually.
PEDAL
SIMPLIFIED
ACCUMULA TORS
SPRING
REMOTESUPPLYPRESSURE
INTERNALRETURN
CROSSINGANDJOININGLINES
INTERNAL SUPPLYPRESSURE
COMPLETE
HYDRAULICANDPNE UMATICCYLIND ERS
Tap Locations Pressure, Sampling, and Sensor Tap Number A B
Desc ripti on
B8
LIF T R O D EN D LN I E R EL I E F
D8
C
LIF T H E AD E N D LI N E R E LEI F
D8
D
A UX L N I ER E LEI F
D7 D7
E
A UX L N I ER E LEI F
F
P LI OT SU P P LY
C2
G
S TE ER P U M P CU TO FF
C3
H
SPR I N GL O D AE D
Schematic Location
MAINSYSRLF
B RA KE CH A R GE
B1
I
F AN D R I VE S G I NA L
B1
J
FRO NTBR A K E AC C U MUL ATO R
F2
K
R E AR B R A K E A CC U M ULA TOR
F2
L
F RO NT B R A KE S UP PL Y
F4
M
R EA R BR AK E SU PP LY
F4
GASC HAR GED
LINESCROSSING
HYDRAULICP UMPS
91 92
34
A
1
45
11
2
51
31
F
8
77
13
50 25 42
85
FIXED DISPLACEMENT
Ahydraulically engaged, multiple disc service brake is located bet ween the planetaries and the differentialat each axle. Each brake contains a piston, discs and plates. When either brake pedalis depressed, pressure oil moves the piston which compressesthe discs against the plates. The heat from brake friction is removed by the oilin the differentialhousing.
78
VARIABLEDISPLACEMENT NON-COMPENSATED
FIXED DISPLACEMENT
SINGLEACTING
UNIDIRECTIONAL
BIDIRECTIONAL
BIDIRECTIONAL
DOUBLEACTING
INTERNAL PASSAGEWAYS
VARIABLEDISPLACEMENT NON-COMPENSATED
UNIDIRECTIONAL
THREE POSITION
INFINITE POSITIONING
CROSS FLOW
PARALLEL FLOW
FLOWINONE DIRECTION
TWO POSITION
FLOWALLOWEDIN EITHERDIRECTION
SERVICE BRAKE/VALVE
COMPONENT and TAP L OCATIONS
17
26
G
49
Electrical Symbols Table HydraulicSymbols (Electrical)
18 90a
15
16
Transducer (Fluid)
25 21
28
48
In this view, the access panelbehind the cab is open, which provides accessto the hydraulic pumps. 26. Steering pump 28. Pump compensator valve 29. Brake/pilot pump 69. Implement pump G. Steering system pressure tap
Transducer (Gas / Air)
ElectricMotor
86 Pressure Switch (Adjustable)
Pressure Switch
24
The steering controlvalve is located belowthe cab on the left frame rail. The controlvalve directssteering system oilto the steering cylinders and sends signaloilthrough the ballresolver. Controlvalve components shown above are: 15. Ballresolver 16. Back-up relief valve 17. Pressure reducing valve 18. Crossover relief valve 20. Secondaryrelief valve 21. Diverter valve 36. Selector and pressure controlvalve
Generator
25
90b
36
69
M
G
88
20
29
The parking brake controlvalve (48) is located on the right frame rail belowthe cab. The parking brake controlvalve directs oilflowto the parking brake. The parking brake pressure switch (49) sends the park brake pressure status to the Power Train ECM.
LINESJOINING
HYDRAULICMOT ORS ORS
This viewshowsthe axle cooling system componentslocated on the inboard side of the axle oilcooling assembly. The axle cooling fan motor (86 ) turns the fan to drawair through the axle oilcoolers. The rear pump (not shown) supplies oilflow to turn the axle cooling fan motor. Arelief valve (88) limits the oilpressure in the rear axle cooling hydraulic system. The front axle oilfilter (90a ) and the rear axle oilfilter (90b) are a lso shown in this view.
The left and right neutralizer valves (25) are mounted at the articulation joint on top of the rear frame. quad check valve (24) is located on the rear frame to the rear of the neutralizer valves.
NEUTRALIZER/QUAD CHECK VALVES
ElectricalWire
Temperature Switch
ElectricalSymbols (Electrical)
The
T
Pressure Symbol
Temperature Symbol
Level Symbol
Flow Symbol
WireNumberIdentificationCodes
12
50
76
Warning Switch
E l ec t ri c al S ch e ma t ci E xa m pl e
87
H y dr a ul i c Sc h em a ti c Ex a mp l e CurrentStandard
CurrentStandard Harnessidentificationcode Thisexampleindicates wire 135 in harness"AG".
Wire CircuitNumber Identification
WireColor
325-AG135 PK-14 325-PK Circuit Identification Number
35
36
W ier Co l or
PreviousStandard WireColor
Wire
50. Parking brake
35. Steering pump case drain filter. 76. Implement pump case drain filter. 12. Fan pump case drain filter.
The steering pump pressure warning switch is located on the selector and pressure controlvalve (36) on top o f the fueltank on the left side of the machine if the machine is equipped with secondarysteering.
W ier Ga u ge
The axle oilcooler assembly (87) is shown off the machine. The oil cooler assembly is located on the left side of the machine above the fueltank. The axle oil cooler assembly is comprised of two sections with the front axle oilcooler in the lower section, and the rear axle oilcooler in the upper section. The cooler assembly removes the heat from the brake and differentialoiland returns the oilto the axle manifold. The cooler oilflows from the manifold and enters the axle at each brake chamber and at the differentialcase.
13
325-PK-14 B
The secondary steering pump (13) is splined to the front of the transmission output transfer gear near the articulation joint. The pump is ground driven and turns when the machine is moving. If the primary steering pump fails or the engine stops while the machine is moving, the secondarysteering pump supplies oil to the steeringsystem.
CircuitNumber Identification
A
WireGauge (EXAMPLEVALVE)
8
7
6
4
5
2
3
1
88
90
FRONTAXLE
87 50 47
F
F
8 8
9 1 2 6 R o i s N n e m E i D ( R , e g a P 6 3
FRONT AXLE
91
86
89
) s e h c n i 5 3 x s e h c n i 8 4 : s n
51
48 46
M
49
K
REAR BRAKE SUPPLY
87
92
L J
FRONT BRAKE SUPPLY
90
REAR AXLE
51
988H AXLE COOLING SYSTEM
WARNING SWI TCH
45
11 E
E
LIFT CYLINDER
66
TILT CYLINDER
LIFT CYLINDER
67
REARAXLE
68
22
STEERING
23
CYLINDERS
55
52
53
B
C
54
58
57
65
D
E
15
65
14
21
18
D
D
16
56 85
63
20
19
RACK
LOWER
63 78
64 63 64
72
RIDE
13
31
CONTROL
64
32
59 19
61
17
41
F
80
WARNING SWITCH
10
24
9
37
60 25 C
60 62
60
RAISE
79
RIGHT
LEFT
NEUTRALIZER
NEUTRALIZER
42
36
12
C
PUMP CASE FILL PORT
27
25
DUMP
38
28
33
FLUID SAMPLING PORT
G
PUMP CASE AIR BLEED
7 STEER
26
30
FANSPEED
35
HYDRAULIC
I
ON/OFF
43 35
77 75
A
44
71
82
84
74
H
83
PUMP CASE FILL PORT
B
81
B
2
PUMP CASE AIR BLEED
IMPL PILOT SUPPLY
40 1 39
4
4
PUMP CASE DRAIN
70
34 3
IMPL RETURN
73
3
5
6
4 29
BRAKE VALVE RETURN
69
76
AIR BLEED
IMPL PUMP INLET
IMPLEMENT SYSTEM
STEERING AND BRAKE SYSTEM LINE PATTERNS
PressureLine Pilot/Load SensingPressure
LINES GROUP COLOR DESCRIPTIONS MAINPUMPOUTPUT
Drain / Return Lines
COOLIN GFAN CIRCUI T
ComponentGroup
PILOT/BRAKEPUMPOUTPUT
A
SUPPLYLINE
Attachment
DRAIN/RETURNLINE STEERINGCIRCUIT AXLECOOLING
Air Line
CIRCUIT
AXLE COOLINGPUMP
CALLOUTS
BRAKECIRCUIT LIFTCIRCUIT IMPLEMENT VALVE LOCK CONTROL CIRCUIT TILTCIRCUIT AUXILLARY CI RCUIT SUPPLEMENTA L STEERING
YY
Taps
52
Components bynumber
(Pressure,Sampling,Sensor)byletter
THISSCHEMATICISFORTHE988HWheelLoader Part#: 225-5542:988HHydraulicSchematic 260-0866: Brake Schematic 259-3116:Axle OilCoolerSchematic Components are shown installed on a fully operable machine with the key and engine
A
