Komatsu PC128US-8 Install guide

WEN00003-00
HYDRAULIC
EXCAVATOR
PC128US-8
SERIAL NUMBERS 20001 and up
aArm crane cannot be used on this machine.

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PC128US-8 00-1
HYDRAULIC EXCAVATOR
1SHOP MANUAL
PC128US-8
Machine model Serial number
PC128US-8 20001 and up
00 Index and foreword 1
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00-2 PC128US-8
00 Index and foreword
Table of contents
Index
Table of contents 1
00 Index and foreword
Index .................................................................................................................................................. 00-2
Table of contents............................................................................................................................ 00-2
Foreword and general information..................................................................................................... 00-9
Safety notice................................................................................................................................... 00-9
How to read the shop manual......................................................................................................... 00-14
Explanation of terms for maintenance standard............................................................................. 00-16
Handling of electric equipment and hydraulic component.............................................................. 00-18
Handling of connectors newly used for engines............................................................................. 00-27
How to read electric wire code ....................................................................................................... 00-30
Precautions when carrying out operation....................................................................................... 00-33
Method of disassembling and connecting push-pull type coupler.................................................. 00-36
Standard tightening torque table .................................................................................................... 00-39
Conversion table............................................................................................................................. 00-43
01 Specification
Specification and technical data......................................................................................................... 01-3
Specification dimension drawing.................................................................................................... 01-3
Working range diagram.................................................................................................................. 01-4
Specifications ................................................................................................................................. 01-5
Weight table.................................................................................................................................... 01-8
Table of fuel, coolant and lubricants............................................................................................... 01-10
10 Structure, function and maintenance standard
Engine and cooling system................................................................................................................ 10-4
Engine and cooling system............................................................................................................. 10-4
PTO................................................................................................................................................ 10-5
Cooling system............................................................................................................................... 10-6
Power train......................................................................................................................................... 10-8
Power train ..................................................................................................................................... 10-8
Swing circle .................................................................................................................................... 10-9
Swing machinery............................................................................................................................ 10-10
Undercarriage and frame................................................................................................................... 10-12
Track frame .................................................................................................................................... 10-12
Idler cushion................................................................................................................................... 10-13
Idler................................................................................................................................................. 10-14
Track roller...................................................................................................................................... 10-15
Carrier roller.................................................................................................................................... 10-16
Sprocket ......................................................................................................................................... 10-17
Track shoe...................................................................................................................................... 10-18
Hydraulic system................................................................................................................................ 10-24
Hydraulic equipment layout drawing............................................................................................... 10-24
Valve control................................................................................................................................... 10-26
Hydraulic tank and filter.................................................................................................................. 10-28
Hydraulic pump............................................................................................................................... 10-30
Control valve................................................................................................................................... 10-56
CLSS.............................................................................................................................................. 10-68
Functions and operation by valve................................................................................................... 10-72
PPC valve....................................................................................................................................... 10-102
Swing motor.................................................................................................................................... 10-119
Travel motor ................................................................................................................................... 10-127
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PC128US-8 00-3
00 Index and foreword
Table of contents
Center swivel joint.......................................................................................................................... 10-136
Solenoid valve................................................................................................................................ 10-140
PPC accumulator ........................................................................................................................... 10-144
Holding valve.................................................................................................................................. 10-146
Work equipment................................................................................................................................. 10-152
Work equipment............................................................................................................................. 10-152
Dimensions of components............................................................................................................ 10-154
Hydraulic cylinder........................................................................................................................... 10-158
Cab and its attachments.................................................................................................................... 10-160
Air conditioner ................................................................................................................................ 10-160
Electrical system................................................................................................................................ 10-172
Electronic control system ............................................................................................................... 10-172
Monitor system............................................................................................................................... 10-205
KOMTRAX system......................................................................................................................... 10-219
Sensor............................................................................................................................................ 10-221
20 Standard value table
Standard service value table.............................................................................................................. 20-3
Standard value table for engine related parts ................................................................................ 20-3
Standard value table for chassis related parts ............................................................................... 20-4
30 Testing and adjusting
Related information on testing and adjusting..................................................................................... 30-3
Tools for testing, adjusting, and troubleshooting............................................................................ 30-3
Sketches of special tools................................................................................................................ 30-7
Engine and cooling system................................................................................................................ 30-8
Testing engine speed..................................................................................................................... 30-8
Testing exhaust temperature.......................................................................................................... 30-9
Checking exhaust gas color ........................................................................................................... 30-10
Adjusting valve clearance............................................................................................................... 30-11
Testing compression pressure....................................................................................................... 30-13
Testing blow-by pressure............................................................................................................... 30-15
Testing engine oil pressure............................................................................................................ 30-16
Handling fuel system parts............................................................................................................. 30-17
Releasing residual pressure from fuel system ............................................................................... 30-17
Testing fuel pressure...................................................................................................................... 30-18
Testing fuel return rate and fuel leakage........................................................................................ 30-19
Bleeding air from fuel circuit........................................................................................................... 30-21
Checking fuel circuit for leakage .................................................................................................... 30-23
Testing and adjusting alternator belt tension.................................................................................. 30-24
Checking and adjusting air conditioner compressor belt tension................................................... 30-25
Power train......................................................................................................................................... 30-26
Testing swing circle bearing clearance .......................................................................................... 30-26
Undercarriage and frame................................................................................................................... 30-27
Checking and adjusting track shoe tension.................................................................................... 30-27
Hydraulic system................................................................................................................................ 30-29
Testing and adjusting oil pressure in work equipment, swing, and travel circuits.......................... 30-29
Testing control circuit basic pressure............................................................................................. 30-32
Testing and adjusting oil pressure in pump PC control circuit........................................................ 30-33
Testing and adjusting oil pressure in pump LS control circuit........................................................ 30-36
Testing solenoid valve output pressure.......................................................................................... 30-40
Testing PPC valve output pressure................................................................................................ 30-41
Adjusting play of work equipment and swing PPC valves.............................................................. 30-43
Checking parts which cause hydraulic drift of work equipment...................................................... 30-44
Testing and adjusting travel deviation............................................................................................ 30-46
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00-4 PC128US-8
00 Index and foreword
Table of contents
Releasing residual pressure from hydraulic circuit......................................................................... 30-48
Testing oil leakage.......................................................................................................................... 30-49
Bleeding air from each part ............................................................................................................ 30-52
Cab and its attachments .................................................................................................................... 30-54
Checking cab tipping stopper......................................................................................................... 30-54
Adjusting mirrors............................................................................................................................. 30-54
Electrical system................................................................................................................................ 30-56
Special functions of machine monitor............................................................................................. 30-56
Handling voltage circuit of engine controller................................................................................... 30-108
Preparation work for troubleshooting of electrical system.............................................................. 30-109
Procedure for testing diodes........................................................................................................... 30-114
Pm-Clinic............................................................................................................................................ 30-115
Pm Clinic service............................................................................................................................ 30-115
40 Troubleshooting
Related information on troubleshooting ............................................................................................. 40-6
Points to remember when performing troubleshooting................................................................... 40-6
How to proceed in troubleshooting................................................................................................. 40-8
Checks before troubleshooting....................................................................................................... 40-10
Classification and procedures for troubleshooting.......................................................................... 40-11
Information in troubleshooting table ............................................................................................... 40-12
Phenomena looking like troubles and troubleshooting Nos............................................................ 40-14
Connection table of connector by No. of pins................................................................................. 40-17
T-box and T-adapter list ................................................................................................................. 40-54
Failure code table........................................................................................................................... 40-58
Fuse locations ................................................................................................................................ 40-62
Troubleshooting by failure code......................................................................................................... 40-64
Failure code [989L00] Engine controller lock caution 1.................................................................. 40-64
Failure code [989M00] Engine controller lock caution 2................................................................. 40-64
Failure code [989N00] Engine controller lock caution 3................................................................. 40-65
Failure code [AB00KE] Charge voltage low ................................................................................... 40-66
Failure code [B@BAZG] Eng oil press. low.................................................................................... 40-68
Failure code [B@BAZK] Eng oil level low ...................................................................................... 40-68
Failure code [B@BCNS] Eng coolant overheat.............................................................................. 40-69
Failure code [B@HANS] Hydr oil overheat..................................................................................... 40-69
Failure code [CA111] ECM critical internal failure.......................................................................... 40-70
Failure code [CA115] Eng. Ne and Bkup speed sensor error ........................................................ 40-73
Failure code [CA122] Charge air press sensor high error.............................................................. 40-74
Failure code [CA123] Charge air press sensor low error ............................................................... 40-76
Failure code [CA131] Throttle sensor high error ............................................................................ 40-78
Failure code [CA132] Throttle sensor low error.............................................................................. 40-80
Failure code [CA144] Coolant temp. sensor high error.................................................................. 40-81
Failure code [CA145] Coolant temp. sensor low error.................................................................... 40-82
Failure code [CA153] Charge air temp. sensor high error.............................................................. 40-83
Failure code [CA154] Charge air temp. sensor low error............................................................... 40-84
Failure code [CA187] Sensor sup. 2 volt. low error........................................................................ 40-85
Failure code [CA221] Ambient air press. sensor high error............................................................ 40-86
Failure code [CA222] Ambient air press. sensor low error............................................................. 40-88
Failure code [CA227] Sensor sup. 2 volt. high error....................................................................... 40-90
Failure code [CA234] Eng. overspeed............................................................................................ 40-91
Failure code [CA238] Ne speed sensor sup. volt. error.................................................................. 40-92
Failure code [CA271] IMV/PCV1 short error .................................................................................. 40-94
Failure code [CA272] IMV/PCV1 open error .................................................................................. 40-95
Failure code [CA322] Injector #1 (L #1) system open/short error................................................... 40-96
Failure code [CA324] Injector #3 (L #3) system open/short error................................................... 40-98
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PC128US-8 00-5
00 Index and foreword
Table of contents
Failure code [CA331] Injector #2 (L #2) system open/short error .................................................. 40-100
Failure code [CA332] Injector #4 (L #4) system open/short error .................................................. 40-102
Failure code [CA351] Inj. drive circuit error.................................................................................... 40-104
Failure code [CA352] Sensor sup. 1 volt. low error........................................................................ 40-107
Failure code [CA386] Sensor sup. 1 volt. high error ...................................................................... 40-108
Failure code [CA435] Abnormality in engine oil pressure switch ................................................... 40-110
Failure code [CA441] Battery voltage low error.............................................................................. 40-111
Failure code [CA442] Battery voltage high error............................................................................ 40-111
Failure code [CA449] Rail press. very high error ........................................................................... 40-112
Failure code [CA451] Rail press. sensor high error ....................................................................... 40-114
Failure code [CA452] Rail press. sensor low error......................................................................... 40-116
Failure code [CA553] Rail press. high error................................................................................... 40-116
Failure code [CA559] Rail press. low error..................................................................................... 40-117
Failure code [CA689] Eng. Ne speed sensor error ........................................................................ 40-120
Failure code [CA731] Eng. Bkup speed sensor phase error.......................................................... 40-122
Failure code [CA757] All persistent data lost error......................................................................... 40-122
Failure code [CA778] Eng. Bkup speed sensor error..................................................................... 40-124
Failure code [CA1633] KOMNET datalink timeout error ................................................................ 40-126
Failure code [CA2185] Throttle sens. sup. volt. high error............................................................. 40-128
Failure code [CA2186] Throttle sens. sup. volt. low error .............................................................. 40-130
Failure code [CA2249] Rail press. very low error........................................................................... 40-130
Failure code [CA2311] Abnormality in IMV solenoid...................................................................... 40-131
Failure code [D110KB] Battery relay drive short............................................................................ 40-132
Failure code [D19JKZ] Personal code relay abnormality............................................................... 40-134
Failure code [D862KA] GPS antenna discon................................................................................. 40-136
Failure code [DA22KK] Pump solenoid power low error................................................................ 40-138
Failure code [DA25KP] 5V sensor 1 power abnormality................................................................ 40-140
Failure code [DA26KP] 5V sensor 2 power abnormality................................................................ 40-143
Failure code [DA2RMC] CAN discon (Pump controller detected).................................................. 40-144
Failure code [DAF8KB] Short circuit in camera power supply........................................................ 40-146
Failure code [DAFGMC] GPS module error................................................................................... 40-148
Failure code [DAFRMC] CAN discon (Monitor detected)............................................................... 40-150
Failure code [DGH2KB] Hydr oil sensor short................................................................................ 40-152
Failure code [DHPAMA] Pump press sensor abnormality.............................................................. 40-154
Failure code [DHSFMA] Travel left forward PPC press sensor abnormality.................................. 40-156
Failure code [DHSGMA] Travel right forward PPC press sensor abnormality ............................... 40-158
Failure code [DHSHMA] Travel left reverse PPC press sensor abnormality.................................. 40-160
Failure code [DHSJMA] Travel right reverse PPC press sensor abnormality................................ 40-162
Failure code [DHSKMA] Blade raise PPC press sensor abnormality............................................. 40-164
Failure code [DHSLMA] Blade lower PPC press sensor abnormality............................................ 40-166
Failure code [DHX1MA] Overload sensor abnormality (Analog).................................................... 40-168
Failure code [DV20KB] Travel alarm S/C....................................................................................... 40-169
Failure code [DW43KA] Travel speed sol discon........................................................................... 40-170
Failure code [DW43KB] Travel speed sol short ............................................................................. 40-171
Failure code [DW45KA] Swing brake sol discon............................................................................ 40-172
Failure code [DW45KB] Swing brake sol short .............................................................................. 40-174
Failure code [DW91KA] Travel junction sol discon ........................................................................ 40-176
Failure code [DW91KB] Travel junction sol short........................................................................... 40-177
Failure code [DWJ0KA] Merge-divider sol discon.......................................................................... 40-178
Failure code [DWJ0KB] Merge-divider sol short ............................................................................ 40-179
Failure code [DXA8KA] PC-EPC sol discon................................................................................... 40-180
Failure code [DXA8KB] PC-EPC sol short..................................................................................... 40-182
Failure code [DXE4KA] Service current EPC discon ..................................................................... 40-184
Failure code [DXE4KB] Service current EPC short........................................................................ 40-185
Failure code [DY20KA] Wiper working abnormality ....................................................................... 40-186
Failure code [DY20MA] Wiper parking abnormality ....................................................................... 40-188
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00-6 PC128US-8
00 Index and foreword
Table of contents
Failure code [DY2CKA] Washer drive discon................................................................................. 40-190
Failure code [DY2CKB] Washer drive short................................................................................... 40-192
Failure code [DY2DKB] Wiper drive (for) short............................................................................... 40-194
Failure code [DY2EKB] Wiper drive (rev) short.............................................................................. 40-196
Troubleshooting of electrical system (E-mode).................................................................................. 40-198
Before carrying out troubleshooting of electrical system................................................................ 40-198
Information in troubleshooting table ............................................................................................... 40-200
E-1 When starting switch turned ON, machine monitor displays nothing....................................... 40-202
E-2 When starting switch turned ON (before starting engine), basic check item lights up............. 40-204
E-3 Engine does not start (Engine does not turn) .......................................................................... 40-205
E-4 Preheater does not operate..................................................................................................... 40-208
E-5 Automatic warm-up system does not operate (in cold season)............................................... 40-210
E-6 All work equipment, swing, and travel mechanism do not move or cannot be locked............. 40-212
E-7 Precaution lights up while engine is running............................................................................ 40-214
E-8 Emergency stop item lights up while engine is running........................................................... 40-217
E-9 Engine coolant temperature gauge does not indicate normally............................................... 40-218
E-10 Hydraulic oil temperature gauge does not indicate normally................................................. 40-219
E-11 Fuel level gauge does not indicate normally.......................................................................... 40-221
E-12 Contents of display by machine monitor are different from applicable machine.................... 40-223
E-13 Machine monitor does not display some items...................................................................... 40-223
E-14 Function switch does not work............................................................................................... 40-223
E-15 Auto-decelerator does not operate normally.......................................................................... 40-224
E-16 Working mode does not change............................................................................................ 40-225
E-17 Travel speed does not change............................................................................................... 40-226
E-18 Alarm buzzer cannot be stopped........................................................................................... 40-227
E-19 Windshield wiper and window washer do not operate........................................................... 40-228
E-20 Swing holding brake does not operate normally.................................................................... 40-232
E-21 Travel alarm does not sound or does not stop sounding....................................................... 40-234
E-22 Air conditioner does not operate normally (including air conditioner abnormality record) ..... 40-235
E-23 While starting switch is in OFF position, service meter is not displayed................................ 40-247
E-24 Machine monitor cannot be set in service mode.................................................................... 40-247
E-25 Monitoring function does not display lever control signal normally........................................ 40-248
E-26 KOMTRAX system does not operate normally...................................................................... 40-264
Troubleshooting of hydraulic and mechanical system (H-mode)....................................................... 40-265
Information contained in troubleshooting table............................................................................... 40-265
System chart for hydraulic and mechanical systems...................................................................... 40-266
H-1 Speed or power of all work equipment, swing, and travel are low........................................... 40-268
H-2 Engine speed sharply drops or engine stalls........................................................................... 40-269
H-3 No work equipment, travel and swing move............................................................................ 40-270
H-4 Abnormal noise is heard from around hydraulic pump............................................................ 40-270
H-5 Fine control mode does not function........................................................................................ 40-271
H-6 Speed or power of boom is low ............................................................................................... 40-272
H-7 Speed or power of arm is low.................................................................................................. 40-273
H-8 Speed or power of bucket is low.............................................................................................. 40-274
H-9 Work equipment does not move in its single operation........................................................... 40-275
H-10 Hydraulic drift of work equipment is large.............................................................................. 40-276
H-11 Time lag of work equipment is large...................................................................................... 40-277
H-12 Work equipment loaded more is slower during compound operation.................................... 40-277
H-13 Boom RAISE speed is low in compound operation of swing + boom RAISE........................ 40-277
H-14 Travel speed lowers largely during compound operation of work equipment/swing + travel. 40-278
H-15 Machine deviates during travel.............................................................................................. 40-279
H-16 Travel speed is low................................................................................................................ 40-280
H-17 Machine cannot be steered easily or steering power is low .................................................. 40-281
H-18 Travel speed does not change or it is kept low or high.......................................................... 40-282
H-19 Track does not move (Only either side)................................................................................. 40-282
H-20 Machine does not swing........................................................................................................ 40-283
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PC128US-8 00-7
00 Index and foreword
Table of contents
H-21 Swing acceleration or swing speed is low............................................................................. 40-284
H-22 Excessive overrun when stopping swing............................................................................... 40-285
H-23 When upper structure stops swinging, it makes large shock................................................. 40-286
H-24 When upper structure stops swinging, it makes large sound ................................................ 40-286
H-25 Hydraulic drift of swing is large.............................................................................................. 40-287
H-26 Flow rate in attachment circuit cannot be adjusted ............................................................... 40-288
Troubleshooting of engine (S-mode) ................................................................................................. 40-290
Method of using troubleshooting chart........................................................................................... 40-290
S-1 Starting performance is poor ................................................................................................... 40-294
S-2 Engine does not start............................................................................................................... 40-295
S-3 Engine does not pick up smoothly........................................................................................... 40-298
S-4 Engine stops during operations............................................................................................... 40-299
S-5 Engine does not rotate smoothly............................................................................................. 40-300
S-6 Engine lacks output (or lacks power)....................................................................................... 40-301
S-7 Exhaust smoke is black (incomplete combustion)................................................................... 40-302
S-8 Oil consumption is excessive (or exhaust smoke is blue) ....................................................... 40-303
S-9 Oil becomes contaminated quickly.......................................................................................... 40-304
S-10 Fuel consumption is excessive.............................................................................................. 40-305
S-11 Oil is in coolant (or coolant spurts back or coolant level goes down) .................................... 40-306
S-12 Oil pressure drops ................................................................................................................. 40-307
S-13 Oil level rises (Entry of coolant or fuel).................................................................................. 40-308
S-14 Coolant temperature becomes too high (overheating) .......................................................... 40-309
S-15 Abnormal noise is made........................................................................................................ 40-310
S-16 Vibration is excessive............................................................................................................ 40-311
50 Disassembly and assembly
General information on disassembly and assembly .......................................................................... 50-4
How to read this manual................................................................................................................. 50-4
Coating materials list...................................................................................................................... 50-6
Special tool list ............................................................................................................................... 50-9
Sketch of special tool ..................................................................................................................... 50-13
Engine and cooling system................................................................................................................ 50-15
Removal and installation of fuel supply pump assembly................................................................ 50-15
Removal and installation of fuel injector assembly......................................................................... 50-17
Removal and installation of front oil seal........................................................................................ 50-20
Removal and installation of rear oil seal......................................................................................... 50-22
Removal and installation of cylinder head assembly...................................................................... 50-25
Removal and installation of radiator assembly............................................................................... 50-32
Removal and installation of aftercooler assembly.......................................................................... 50-34
Removal and installation of work equipment oil cooler assembly .................................................. 50-36
Removal and installation of engine and work equipment pump assembly..................................... 50-39
Removal and installation of fuel tank assembly ............................................................................. 50-44
Power train......................................................................................................................................... 50-46
Removal and installation of travel motor and final drive assembly................................................. 50-46
Disassembly and assembly of travel motor and final drive assembly ............................................ 50-48
Removal and installation of swing motor and swing machinery assembly..................................... 50-84
Disassembly and assembly of swing motor and swing machinery assembly ................................ 50-86
Removal and installation of swing circle assembly ........................................................................ 50-92
Undercarriage and frame................................................................................................................... 50-93
Disassembly and assembly of track roller...................................................................................... 50-93
Disassembly and assembly of idler assembly................................................................................ 50-96
Disassembly and assembly of recoil spring ................................................................................... 50-99
Spreading and installation of track shoe assembly........................................................................ 50-102
Removal and installation of sprocket.............................................................................................. 50-104
Removal and installation of revolving frame assembly .................................................................. 50-105
Removal and installation of counterweight assembly (Machine without add-on weight)................ 50-107
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00-8 PC128US-8
00 Index and foreword
Table of contents
Removal and installation of counterweight assembly (Machine with add-on weight)..................... 50-109
Hydraulic system................................................................................................................................ 50-111
Removal and installation of center swivel joint assembly............................................................... 50-111
Disassembly and assembly of center swivel joint assembly .......................................................... 50-113
Removal and installation of hydraulic tank assembly..................................................................... 50-114
Removal and installation of hydraulic pump assembly................................................................... 50-117
Removal and installation of control valve assembly....................................................................... 50-121
Disassembly and assembly of control valve assembly................................................................... 50-126
Disassembly and assembly of work equipment PPC valve assembly............................................ 50-136
Disassembly and assembly of travel PPC valve assembly............................................................ 50-139
Disassembly and assembly of hydraulic cylinder assembly........................................................... 50-141
Work equipment................................................................................................................................. 50-147
Removal and installation of work equipment assembly.................................................................. 50-147
Cab and its attachments .................................................................................................................... 50-150
Removal and installation of operator cab assembly....................................................................... 50-150
Removal and Installation of operator's cab door............................................................................ 50-152
Removal and installation of operator's cab glass (stuck glass)...................................................... 50-155
Removal and installation of front window assembly....................................................................... 50-164
Removal and installation of floor frame assembly.......................................................................... 50-165
Electrical system................................................................................................................................ 50-172
Removal and installation of air compressor assembly ................................................................... 50-172
Removal and installation of air conditioner condenser................................................................... 50-173
Removal and installation of air conditioner unit assembly.............................................................. 50-174
Removal and installation of machine monitor assembly................................................................. 50-177
Removal and installation of pump controller assembly .................................................................. 50-178
Removal and installation of engine controller assembly................................................................. 50-179
Removal and installation of KOMTRAX communications module.................................................. 50-180
90 Diagrams and drawings
Hydraulic diagrams and drawings...................................................................................................... 90-3
Symbols used in hydraulic circuit diagrams.................................................................................... 90-3
Hydraulic circuit diagram................................................................................................................ 90-5
Electrical diagrams and drawings ...................................................................................................... 90-9
Symbols used in electric circuit diagrams.......................................................................................90-9
Electrical circuit diagram ................................................................................................................ 90-13
Connectors table and arrangement drawing .................................................................................. 90-25
Index ..................................................................................................................................................... 1
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PC128US-8 00-9
00 Index and foreword
Safety notice
Foreword and general information
Safety notice (Rev. 2008/08)
Important safety notice
Proper service and repair are extremely important for safe machine operation. The service and repair
techniques recommended by Komatsu and described in this manual are both effective and safe. Some
of these techniques require the use of tools specially designed by Komatsu for the specific purpose.
To prevent injury to workers, the symbol kis used to mark safety precautions in this manual. The
cautions accompanying these symbols should always be followed carefully. If any dangerous situa-
tion arises or may possibly arise, first consider safety, and take the necessary actions to deal with
the situation.
1. General precautions
kMistakes in operation are extremely
dangerous. Read the Operation and
Maintenance Manual carefully before
operating the machine. In addition,
read this manual and understand its
contents before starting the work.
1) Before carrying out any greasing or
repairs, read all the safety labels stuck to
the machine. For the locations of the
safety labels and detailed explanation of
precautions, see the Operation and Main-
tenance Manual.
2) Decide a place in the repair workshop to
keep tools and removed parts. Always
keep the tools and parts in their correct
places. Always keep the work area clean
and make sure that there is no dirt, water,
or oil on the floor. Smoke only in the areas
provided for smoking. Never smoke while
working.
3) When carrying out any operation, always
wear safety shoes and helmet. Do not
wear loose work clothes, or clothes with
buttons missing.
qAlways wear safety glasses when hit-
ting parts with a hammer.
qAlways wear safety glasses when
grinding parts with a grinder, etc.
4) When carrying out any operation with 2 or
more workers, always agree on the oper-
ating procedure before starting. Always
inform your fellow workers before starting
any step of the operation. Before starting
work, hang UNDER REPAIR warning
signs in the operator's compartment.
5) Only qualified workers must carry out work
and operation which require license or
qualification.
6) Keep all tools in good condition, learn the
correct way to use them, and use the
proper ones of them. Before starting work,
thoroughly check the tools, machine, fork-
lift, service car, etc.
7) If welding repairs are needed, always
have a trained and experienced welder
carry out the work. When carrying out
welding work, always wear welding
gloves, apron, shielding goggles, cap and
other clothes suited for welding work.
8) Before starting work, warm up your body
thoroughly to start work under good condi-
tion.
9) Avoid continuing work for long hours and
take rests at proper intervals to keep your
body in good condition. Take rests in
specified safe places.
Safety points
1 Good arrangement
2 Correct work clothes
3 Following work standard
4 Making and checking signs
5Prohibition of operation and handling by
unlicensed workers
6 Safety check before starting work
7Wearing protective goggles
(for cleaning or grinding work)
8Wearing shielding goggles and protectors
(for welding work)
9 Good physical condition and preparation
10 Precautions against work which you are
not used to or you are used to too much

00-10 PC128US-8
00 Index and foreword
Safety notice
2. Preparations for work
1) Before adding oil or making any repairs,
park the machine on a hard and level
ground, and apply the parking brake and
block the wheels or tracks to prevent the
machine from moving.
2) Before starting work, lower the work
equipment (blade, ripper, bucket, etc.) to
the ground. If this is not possible, insert
the lock pin or use blocks to prevent the
work equipment from falling. In addition,
be sure to lock all the control levers and
hang warning signs on them.
3) When disassembling or assembling, sup-
port the machine with blocks, jacks, or
stands before starting work.
4) Remove all mud and oil from the steps or
other places used to get on and off the
machine. Always use the handrails, lad-
ders or steps when getting on or off the
machine. Never jump on or off the
machine. If it is impossible to use the
handrails, ladders or steps, use a stand to
provide safe footing.
3. Precautions during work
1) Before disconnecting or removing compo-
nents of the oil, water, or air circuits, first
release the pressure completely from the
circuit. When removing the oil filler cap, a
drain plug, or an oil pressure pickup plug,
loosen it slowly to prevent the oil from
spurting out.
2) The coolant and oil in the circuits are hot
when the engine is stopped, so be careful
not to get scalded. Wait for the oil and
coolant to cool before carrying out any
work on the oil or water circuits.
3) Before starting work, stop the engine.
When working on or around a rotating
part, in particular, stop the engine. When
checking the machine without stopping
the engine (measuring oil pressure,
revolving speed, temperature, etc.), take
extreme care not to get rolled or caught in
rotating parts or moving parts.
4) Before starting work, remove the leads
from the battery. Always remove the lead
from the negative (–) terminal first.
5) When raising a heavy component (heavier
than 25 kg), use a hoist or crane. Before
starting work, check that the slings (wire
ropes, chains, and hooks) are free from
damage. Always use slings which have
ample capacity and install them to proper
places. Operate the hoist or crane slowly
to prevent the component from hitting any
other part. Do not work with any part still
raised by the hoist or crane.
6) When removing a cover which is under
internal pressure or under pressure from a
spring, always leave 2 bolts in diagonal
positions. Loosen those bolts gradually
and alternately to release the pressure,
and then remove the cover.
7) When removing components, be careful
not to break or damage the electrical wir-
ing. Damaged wiring may cause electrical
fires.
8) When removing piping, stop the fuel or oil
from spilling out. If any fuel or oil drips
onto the floor, wipe it up immediately. Fuel
or oil on the floor can cause you to slip
and can even start fires.
9) As a general rule, do not use gasoline to
wash parts. Do not use it to clean electri-
cal parts, in particular.
10) Be sure to assemble all parts again in their
original places. Replace any damaged
parts and parts which must not be reused
with new parts. When installing hoses and
wires, be sure that they will not be dam-
aged by contact with other parts when the
machine is operated.
11) When installing high pressure hoses,
make sure that they are not twisted. Dam-
aged tubes are dangerous, so be
extremely careful when installing tubes for
high pressure circuits. In addition, check
that connecting parts are correctly
installed.
12) When assembling or installing parts,
always tighten them to the specified
torques. When installing protective parts
such as guards, or parts which vibrate vio-
lently or rotate at high speed, be particu-
larly careful to check that they are
installed correctly.
13) When aligning 2 holes, never insert your
fingers or hand. Be careful not to get your
fingers caught in a hole.
14) When measuring hydraulic pressure,
check that the measuring tools are cor-
rectly assembled.
15) Take care when removing or installing the
tracks of track-type machines. When
removing the track, the track separates
suddenly, so never let anyone stand at
either end of the track.
16) If the engine is operated for a long time in
a place which is not ventilated well, you
may suffer from gas poisoning. Accord-
ingly, open the windows and doors to ven-
tilate well.

PC128US-8 00-11
00 Index and foreword
Safety notice
4. Precautions for sling work and making
signs
1) Only one appointed worker must make
signs and co-workers must communicate
with each other frequently. The appointed
sign maker must make specified signs
clearly at a place where he is well seen
from the operator's seat and where he can
see the working condition easily. The sign
maker must always stand in front of the
load and guide the operator safely.
qDo not stand under the load.
qDo not step on the load.
2) Check the slings before starting sling
work.
3) Keep putting on gloves during sling work.
(Put on leather gloves, if available.)
4) Measure the weight of the load by the eye
and check its center of gravity.
5) Use proper sling according to the weight
of the load and method of slinging. If too
thick wire ropes are used to sling a light
load, the load may slip and fall.
6) Do not sling a load with 1 wire rope alone.
If it is slung so, it may rotate and may slip
out of the rope. Install 2 or more wire
ropes symmetrically.
kSlinging with 1 rope may cause
turning of the load during hoisting,
untwisting of the rope, or slipping
of the rope from its original wind-
ing position on the load, which can
result in a dangerous accident.
7) Limit the hanging angle to 60°, as a rule.
Do not sling a heavy load with ropes form-
ing a wide hanging angle from the hook.
When hoisting a load with 2 or more
ropes, the force subjected to each rope
will increase with the hanging angle. The
table below shows the variation of allow-
able load in kN {kg} when hoisting is made
with 2 ropes, each of which is allowed to
sling up to 9.8 kN {1,000 kg} vertically, at
various hanging angles. When the 2 ropes
sling a load vertically, up to 19.6 kN {2,000
kg} of total weight can be suspended.
This weight is reduced to 9.8 kN {1,000
kg} when the 2 ropes make a hanging
angle of 120°. If the 2 ropes sling a 19.6
kN {2,000 kg} load at a lifting angle of
150°, each of them is subjected to a force
as large as 39.2 kN {4,000 kg}.
8) When installing wire ropes to an angular
load, apply pads to protect the wire ropes.
If the load is slippery, apply proper mate-
rial to prevent the wire rope from slipping.
9) Use the specified eyebolts and fix wire
ropes, chains, etc. to them with shackles,
etc.
10) Apply wire ropes to the middle portion of
the hook.
qSlinging near the tip of the hook may
cause the rope to slip off the hook
during hoisting. The hook has the
maximum strength at the middle por-
tion.
11) Do not use twisted or kinked wire ropes.
12) When lifting up a load, observe the follow-
ing.
qWind in the crane slowly until wire
ropes are stretched. When settling
the wire ropes with the hand, do not
grasp them but press them from
above. If you grasp them, your fingers
may be caught.
qAfter the wire ropes are stretched,
stop the crane and check the condi-
tion of the slung load, wire ropes, and
pads.

00-12 PC128US-8
00 Index and foreword
Safety notice
qIf the load is unstable or the wire rope
or chains are twisted, lower the load
and lift it up again.
qDo not lift up the load slantingly.
13) When lifting down a load, observe the fol-
lowing.
qWhen lifting down a load, stop it tem-
porarily at 30 cm above the floor, and
then lower it slowly.
qCheck that the load is stable, and
then remove the sling.
qRemove kinks and dirt from the wire
ropes and chains used for the sling
work, and put them in the specified
place.
5. Precautions for using mobile crane
aRead the Operation and Maintenance
Manual of the crane carefully in advance
and operate the crane safely.
6. Precautions for using overhead hoist crane
kWhen raising a heavy part (heavier
than 25 kg), use a hoist, etc. In Disas-
sembly and assembly, the weight of a
part heavier than 25 kg is indicated
after the mark of 4.
1) Before starting work, inspect the wire
ropes, brake, clutch, controller, rails, over
wind stop device, electric shock preven-
tion earth leakage breaker, crane collision
prevention device, and power application
warning lamp, and check safety.
2) Observe the signs for sling work.
3) Operate the hoist at a safe place.
4) Check the direction indicator plates (east,
west, south, and north) and the directions
of the control buttons without fail.
5) Do not sling a load slantingly. Do not move
the crane while the slung load is swinging.
6) Do not raise or lower a load while the
crane is moving longitudinally or laterally.
7) Do not drag a sling.
8) When lifting up a load, stop it just after it
leaves the ground and check safety, and
then lift it up.
9) Consider the travel route in advance and
lift up a load to a safe height.
10) Place the control switch on a position
where it will not be an obstacle to work
and passage.
11) After operating the hoist, do not swing the
control switch.
12) Remember the position of the main switch
so that you can turn off the power immedi-
ately in an emergency.
13) If the hoist stops because of a power fail-
ure, turn the power switch OFF. When
turning on a switch which was turned OFF
by the electric shock prevention earth
leakage breaker, check that the devices
related to that switch are not in operation
state.
14) If you find an obstacle around the hoist,
stop the operation.
15) After finishing the work, stop the hoist at
the specified position and raise the hook
to at least 2 m above the floor. Do not
leave the sling installed to the hook.
7. Selecting wire ropes
1) Select adequate ropes depending on the
weight of parts to be hoisted, referring to
the table below.
aThe allowable load is one-sixth of the
breaking strength of the rope used
(Safety coefficient: 6).
Wire ropes
(Standard “Z” twist ropes without galvanizing)
(JIS G3525, No. 6, Type 6X37-A)
Nominal
diameter of rope Allowable load
mm kN ton
10 8.8 0.9
12 12.7 1.3
14 17.3 1.7
16 22.6 2.3
18 28.6 2.9
20 35.3 3.6
25 55.3 5.6
30 79.6 8.1
40 141.6 14.4
50 221.6 22.6
60 318.3 32.4

PC128US-8 00-13
00 Index and foreword
Safety notice
8. Precautions for disconnecting and con-
necting hoses and tubes in air conditioner
circuit
1) Disconnection
kFor the environment, the air condi-
tioner of this machine uses the
refrigerant (air conditioner gas:
R134a) which has fewer factors of
the depletion of the ozone layer.
However, it does not mean that you
may discharge the refrigerant into
the atmosphere as it is. Be sure to
recover the refrigerant when dis-
connecting the refrigerant gas cir-
cuit and then reuse it.
aAsk professional traders for collecting
and filling operation of refrigerant
(R134a).
aNever release the refrigerant (R134a)
to the atmosphere.
kIf the refrigerant gas gets in your
eyes or contacts your skin, you
may lose your sight and your skin
may be frozen. Accordingly, put
on safety glasses, safety gloves
and safety clothes when recover-
ing or adding the refrigerant.
Refrigerant gas must be recovered
and added by a qualified person.
2) Connection
1] When installing the air conditioner cir-
cuit hoses and tubes, take care that
dirt, dust, water, etc. will not enter
them.
2] When connecting the air conditioner
hoses and tubes, check that O-rings
(1) are fitted to their joints.
3] Check that each O-ring is not dam-
aged or deteriorated.
4] When connecting the refrigerant pip-
ing, apply compressor oil for refriger-
ant (R134a) (DENSO: ND-OIL8,
VALEO THERMAL SYSTEMS:
ZXL100PG (equivalent to PAG46))
to its O-rings.
aExample of O-ring (Fitted to every joint of
hoses and tubes)
aFor tightening torque, see the precautions for
installation in each section of "Disassembly
and assembly".

00-14 PC128US-8
00 Index and foreword
How to read the shop manual
How to read the shop manual 1
1. Composition of shop manual
This shop manual contains the necessary technical information for services performed in a workshop.
For ease of understanding, the manual is divided into the following sections.
00. Index and foreword
This section explains the shop manuals list, table of contents, safety, and basic information.
01. Specification
This section explains the specifications of the machine.
10. Structure, function and maintenance standard
This section explains the structure, function, and maintenance standard values of each component.
The structure and function sub-section explains the structure and function of each component. It
serves not only to give an understanding of the structure, but also serves as reference material for
troubleshooting. The maintenance standard sub-section explains the criteria and remedies for dis-
assembly and service.
20. Standard value table
This section explains the standard values for new machine and judgement criteria for testing,
adjusting, and troubleshooting. This standard value table is used to check the standard values in
testing and adjusting and to judge parts in troubleshooting.
30. Testing and adjusting
This section explains measuring instruments and measuring methods for testing and adjusting, and
method of adjusting each part. The standard values and judgement criteria for testing and adjusting
are explained in Testing and adjusting.
40. Troubleshooting
This section explains how to find out failed parts and how to repair them. The troubleshooting is
divided by failure modes. The “S mode” of the troubleshooting related to the engine may be also
explained in the Chassis volume and Engine volume. In this case, see the Chassis volume.
50. Disassembly and assembly
This section explains the special tools and procedures for removing, installing, disassembling, and
assembling each component, as well as precautions for them. In addition, tightening torque and
quantity and weight of coating material, oil, grease, and coolant necessary for the work are also
explained.
90. Diagrams and drawings (chassis volume)/Repair and replacement of parts (engine volume)
qChassis volume
This section gives hydraulic circuit diagrams and electrical circuit diagrams.
qEngine volume
This section explains the method of reproducing, repairing, and replacing parts.
2. Revision and distribution
Any additions, revisions, or other change of notices will be sent to KOMATSU distributors. Get the most
up-to-date information before you start any work.
qSome attachments and optional parts in this shop manual may not be delivered to certain areas. If one
of them is required, consult KOMATSU distributors.
qMaterials and specifications are subject to change without notice.
qShop manuals are divided into the “Chassis volume” and “Engine volume”. For the engine unit, see the
engine volume of the engine model mounted on the machine.

PC128US-8 00-15
00 Index and foreword
How to read the shop manual
3. Filing method
File by the brochures in the correct order of the form number printed in the shop manual composition
table.
qRevised edition mark
When a manual is revised, the ones and tens digits of the form number of each brochure is
increased by 1. (Example: 00, 01, 02 …)
qRevisions
Revised brochures are shown in the shop manual composition table.
4. Symbols
Important safety and quality portions are marked with the following symbols so that the shop manual will
be used practically.
5. Units
In this shop manual, the units are indicated with International System of units (SI). For reference, con-
ventionally used Gravitational System of units is indicated in parentheses { }.
Symbol Item Remarks
kSafety Special safety precautions are necessary when performing work.
aCaution Special technical precautions or other precautions for preserving stan-
dards are necessary when performing work.
4Weight Weight of parts of component or parts. Caution necessary when
selecting hoisting wire, or when working posture is important, etc.
3Tightening
torque Places that require special attention for tightening torque during assembly.
2Coat Places to be coated with adhesives, etc. during assembly.
5Oil, coolant Places where oil, etc. must be added, and capacity.
6Drain Places where oil, etc. must be drained, and quantity to be drained.

00-16 PC128US-8
00 Index and foreword
Explanation of terms for maintenance standard
Explanation of terms for maintenance standard 1
The maintenance standard chapter explains the criteria for replacing or reusing products and parts in the
machine maintenance work. The following terms are used to explain the criteria.
1. Standard size and tolerance
qTo be accurate, the finishing size of parts
is a little different from one to another.
qTo specify a finishing size of a part, a tem-
porary standard size is set and an allow-
able difference from that size is indicated.
qThe above size set temporarily is called
the “standard size” and the range of differ-
ence from the standard size is called the
“tolerance”.
qThe tolerance with the symbols of + or – is
indicated on the right side of the standard
size.
aThe tolerance may be indicated in the text
and a table as [standard size (upper limit
of tolerance/lower limit of tolerance)].
Example) 120 (–0.022/–0.126)
qUsually, the size of a hole and the size of
the shaft to be fitted to that hole are indi-
cated by the same standard size and dif-
ferent tolerances of the hole and shaft.
The tightness of fit is decided by the toler-
ance.
qIndication of size of rotating shaft and hole
and relationship drawing of them
Example:
Standard size Tolerance
120 –0.022
–0.126
Example:
Standard size Tolerance
Shaft Hole
60 –0.030
–0.076 +0.046 +0

PC128US-8 00-17
00 Index and foreword
Explanation of terms for maintenance standard
2. Standard clearance and standard value
qThe clearance made when new parts are
assembled is called the “standard clear-
ance“, which is indicated by the range
from the minimum clearance to the maxi-
mum clearance.
qWhen some parts are repaired, the clear-
ance is generally adjusted to the standard
clearance.
qA value of performance and function of
new products or equivalent is called the
“standard value“, which is indicated by a
range or a target value.
qWhen some parts are repaired, the value
of performance/function is set to the stan-
dard value.
3. Standard interference
qWhen the diameter of a hole of a part
shown in the given standard size and tol-
erance table is smaller than that of the
mating shaft, the difference between those
diameters is called the “interference”.
qThe range (A – B) from the difference (A)
between the minimum size of the shaft
and the maximum size of the hole to the
difference (B) between the maximum size
of the shaft and the minimum size of the
hole is the “standard interference”.
qAfter repairing or replacing some parts,
measure the size of their hole and shaft
and check that the interference is in the
standard range.
4. Repair limit and allowable value or allow-
able dimension
qThe size of a part changes because of
wear and deformation while it is used. The
limit of changed size is called the “repair
limit”.
qIf a part is worn to the repair limit, it must
be replaced or repaired.
qThe performance and function of a prod-
uct lowers while it is used. A value which
the product can be used without causing a
problem is called the “allowable value” or
“allowable dimension”.
qIf a product is worn to the allowable value,
it must be checked or repaired. Since the
permissible value is estimated from vari-
ous tests or experiences in most cases,
however, it must be judged after consider-
ing the operating condition and customer's
requirement.
5. Clearance limit
qParts can be used until the clearance
between them is increased to a certain
limit. The limit at which those parts cannot
be used is called the “clearance limit”.
qIf the clearance between the parts
exceeds the clearance limit, they must be
replaced or repaired.
6. Interference limit
qThe allowable maximum interference
between the hole of a part and the shaft of
another part to be assembled is called the
“interference limit”.
qThe interference limit shows the repair
limit of the part of smaller tolerance.
qIf the interference between the parts
exceeds the interference limit, they must
be replaced or repaired.

00-18 PC128US-8
00 Index and foreword
Handling of electric equipment and hydraulic component
Handling of electric equipment and hydraulic component 1
To maintain the performance of the machine over a long period, and to prevent failures or other troubles
before they occur, correct “operation“, “maintenance and inspection“, “troubleshooting“, and “repairs” must
be carried out. This section deals particularly with correct repair procedures for mechatronics and is aimed at
improving the quality of repairs. For this purpose, it gives sections on “Handling electric equipment” and
“Handling hydraulic equipment” (particularly gear oil and hydraulic oil).
Points to remember when handling electric
equipment
1. Handling wiring harnesses and connectors
Wiring harnesses consist of wiring connecting
one component to another component, con-
nectors used for connecting and disconnecting
one wire from another wire, and protectors or
tubes used for protecting the wiring.
Compared with other electrical components fit-
ted in boxes or cases, wiring harnesses are
more likely to be affected by the direct effects
of rain, water, heat, or vibration. Furthermore,
during inspection and repair operations, they
are frequently removed and installed again, so
they are likely to suffer deformation or damage.
For this reason, it is necessary to be extremely
careful when handling wiring harnesses.
2. Main failures occurring in wiring harness
1) Defective contact of connectors (defec-
tive contact between male and female)
Problems with defective contact are likely
to occur because the male connector is
not properly inserted into the female con-
nector, or because one or both of the con-
nectors is deformed or the position is not
correctly aligned, or because there is cor-
rosion or oxidization of the contact sur-
faces. The corroded or oxidized contact
surfaces may become shiny again (and
contact may become normal) by connect-
ing and disconnecting the connector about
10 times.
2) Defective crimping or soldering of connec-
tors
The pins of the male and female connec-
tors are in contact at the crimped terminal
or soldered portion, but if there is exces-
sive force brought to bear on the wiring,
the plating at the joint will peel and cause
improper connection or breakage.