Complete workshop repair service manual with electrical wiring diagrams for Caterpillar 120K & 120K Series 2 Motor Graders. It's the same service manual used by dealers that guaranteed to be fully functional and intact without any missing page.

Caterpillar 120K & 120K Series 2 Motor Graders service & repair manual (including maintenance, overhaul, disassembling & assembling, adjustment, tune-up, operation, inspecting, diagnostic & troubleshooting…) is divided into different sections. Each section covers a specific component or system with detailed illustrations. A table of contents is placed at the beginning of each section. Pages are easily found by category, and each page is expandable for great detail. The printer-ready PDF documents work like a charm on all kinds of devices.

KENR8244 - Schematic (12K; 120K; 140K and 160K Motor Grader Electrical System).pdf
KENR8245 - Schematic (12K; 120K; 140K; and 160K Motor Grader Hydraulic System).pdf
KENR8412 - Specifications (120K and 120K Series 2 Motor Grader Hydraulic and Steering System).pdf
KENR8413 - Systems Operation (120K and 120K Series 2 Motor Graders Hydraulic and Steering System).pdf
KENR8413 - Testing and Adjusting (120K and 120K Series 2 Motor Graders Hydraulic and Steering System).pdf
KENR8413 - Troubleshooting (120K and 120K Series 2 Motor Graders Hydraulic and Steering System).pdf
KENR8414 - Specifications (120K and 120K Series 2 Motor Graders Air System and Brakes).pdf
KENR8415 - Systems Operation (120K and 120K Series 2 Motor Graders Air System and Brakes).pdf
KENR8415 - Testing and Adjusting (120K and 120K Series 2 Motor Graders Air System and Brakes).pdf
KENR8415 - Troubleshooting (120K and 120K Series 2 Motor Graders Air System and Brakes).pdf
KENR8416 - Specifications (120K and 120K Series 2 Motor Graders Power Train).pdf
KENR8437 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Engine Supplement).pdf
KENR8438 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Power Train).pdf
KENR8439 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Machine Systems).pdf
UENR5014 - Schematic (12K, 120K, 140K, and 160K Motor Grader Electrical System).pdf
UENR7717 - Schematic (12K, 120K, 140K, and 160K Motor Grader Electrical System).pdf
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KENR8244 - Schematic (12K; 120K; 140K and 160K Motor Grader Electrical System)....2
KENR8245 - Schematic (12K; 120K; 140K; and 160K Motor Grader Hydraulic System)....4
  Main....5
    Features....5
    Cover Page....6
    Information....0
      Component Location....0
        Volume 1 of 2 - Standard Implement Control Valve configuration....7
        Volume 2 of 2 - Alternate Implement Control Valve Configurations....8
      Tap Location....9
      Fluid Power Symbols....10
      Electrical Symbols....11
    Schematics....0
      Volume 1 of 2 - Standard Implement Control Valve Configuration....12
      Volume 2 of 2 -Alternate Implement Control Valve Configurations....13
    Machine Views....0
      Central Machine Components....14
      Forward Machine Components....15
      LH Implement Control Valve Config1....16
      LH Implement Control Valve Config2....17
      LH Implement Control Valve Config3....18
      LH Implement Control Valve Config4....19
      LH Implement Control Valve Config5....20
      Plow And Dozer Attachment....21
      RH Implement Control Valve Config1....22
      RH Implement Control Valve Config2....23
      RH Implement Control Valve Config3....24
      Scarifier And Ripper Attachments....25
      Swivel, Blade Tip, And Side Shift Cylinders....26
  Collage....27
KENR8412 - Specifications (120K and 120K Series 2 Motor Grader Hydraulic and Steering System)....60
  Hydraulic Tank Mounting....63
  Hydraulic Tank and Filter....64
  Pump Drive Shaft (Implement and Steering)....66
  Piston Pump (Implement; Steering)....67
  Pump Control Valve (Pressure and Flow Compensator)....73
  Relief Valve (Implement)....75
  Relief Valve (Signal)....76
  Steering Control....77
  Accumulator (Blade Cushion)....78
  Solenoid Valve (Blade Cushion)....80
  Springs (Control Valves)....81
  Control Valve (Articulation)....83
  Control Valve (Centershift)....85
  Control Valve (Circle Drive)....87
  Control Valve (Wheel Lean)....89
  Control Valve (Blade Lift)....91
  Relief Valve (Blade Lift)....93
  Control Valve (Blade Tip)....95
  Relief Valve (Blade Tip)....97
  Control Valve (Ripper)....99
  Relief Valve (Ripper)....101
  Control Valve (Scarifier)....103
  Relief Valve (Scarifier)....105
  Control Valve (Sideshift)....106
  Relief Valve (Sideshift)....108
  Control Valve (Snow Plow_Dozer Lift)....110
  Relief Valve (Snow Plow_Dozer Lift)....112
  Control Valve (Wing Lift)....114
  Relief Valve (Wing Lift)....116
  Control Valve (Wing Tilt)....118
  Relief Valve (Wing Tilt)....120
  Relief Valve (Steering)....122
  Articulation Cylinder Mounting....124
  Articulation Cylinder....126
  Position Sender (Articulation)....130
  Circle....133
  Blade Lift Cylinder Mounting....135
  Blade Lift Cylinder....136
  Blade Tip Cylinder....138
  Centershift Cylinder Mounting....140
  Centershift Cylinder....141
  Ball Switch (Centershift Indicator)....143
  Centershift Lock....144
  Solenoid Valve (Centershift Lock)....146
  Ripper Lift Cylinder....148
  Scarifier Cylinder....150
  Sideshift Cylinder....152
  Steering Cylinder....154
  Wheel Lean Cylinder and Mounting....156
  Wheel Lean Cylinder....157
  Gerotor Motor (Circle Drive)....159
  Circle Drive - Slip Clutch....160
  Swivel....165
  Metering Pump (Steering)....167
  Combination Valve....168
  Valve and Linkage Group....172
  Operator Console....176
  Articulated Hitch....181
  Blade Lift....183
  Drawbar....185
  Front Axle....189
  Scarifier....195
KENR8413 - Systems Operation (120K and 120K Series 2 Motor Graders Hydraulic and Steering System)....197
  Introduction....198
  Features....200
  Location Of Components....202
  Implement and Steering System....208
  Implement System....211
  Hydraulic Tank and Filter....214
  Piston Pump (Implement and Steering)....216
  Pump Control Valve (Implement; Steering)....230
  Combination Valve....232
  Control Valve (Implement)....240
  Control Valve (Blade Lift)....243
  Centershift Lock....248
  Steering System....251
  Metering Pump (Steering)....259
KENR8413 - Testing and Adjusting (120K and 120K Series 2 Motor Graders Hydraulic and Steering System)....269
  System Pressure - Release....270
  Pump Efficiency (Piston Pumps) - Test....272
  Bearing End Play (Piston Pump) - Adjust....275
  Pump Control Valve (Implement; Steering) - Test and Adjust....276
  Relief Valves (Implement) - Test and Adjust....290
  Disc Pack Preload for Circle Drive - Adjust....294
  Steering Wheel Slip - Check....298
  Hydraulic Cylinder Drift - Check....299
  Cylinder Cycle Time - Check....302
  Relief Valve (Steering) - Test and Adjust....305
  Steering System - Purge....308
  Steering Linkage - Adjust....312
  Axle Toe-In (Front) - Adjust....314
  Position Sender (Articulation) - Adjust....317
KENR8413 - Troubleshooting (120K and 120K Series 2 Motor Graders Hydraulic and Steering System)....320
  General Information....321
  Machine Preparation for Troubleshooting....322
  Visual Inspection....324
  Operational Checks....326
  Hydraulic and Steering System....327
KENR8414 - Specifications (120K and 120K Series 2 Motor Graders Air System and Brakes)....335
  Air Compressor Governor....336
  Air Tank....338
  Relief Valve (Air Tank)....339
  Check Valve (Air Tank)....340
  Electric Horn....341
  Air Dryer....343
  Air Control Valve (Service Brake)....344
  Pressure Switch (Low Brake Air)....346
  Pressure Switch (Brake Air) (Stop Lamp)....347
  Service Brake Control....348
  Parking Brake Control....352
  Air Control Valve (Parking Brake)....353
  Check Valve (Parking Brake Release)....354
  Solenoid Valve (Parking Brake)....355
  Pressure Switch (Brake Air) (Parking Brake)....357
  Service Brakes....358
  Parking Brake....361
KENR8415 - Systems Operation (120K and 120K Series 2 Motor Graders Air System and Brakes)....363
  Introduction....364
  Location of Components....367
  Air System and Brakes....373
  Monitoring System....374
  Air Dryer - If Equipped....378
  Relief Valve (Air Tank)....380
  Air Control Valve (Service Brakes)....382
  Air Control Valve (Parking Brake)....385
  Service Brakes....387
  Parking Brake....392
  Air System Schematic....396
KENR8415 - Testing and Adjusting (120K and 120K Series 2 Motor Graders Air System and Brakes)....399
  System Pressure - Release....400
  Air System - Test....402
  Air Pressure Gauge - Test....405
  Air Compressor Governor - Test and Adjust....408
  Pressure Switch (Low Brake Air) - Test....412
  Pressure Switch (Brake Air) (Stop Lamp) - Test....415
  Limit Switch (Service Brake) - Test and Adjust....417
  Service Brakes - Test....421
  Service Brake Control (Pedal) - Adjust....423
  Service Brake Control Valve - Check....428
  Bearing Preload for Service Brake - Adjust....433
  Brake Disc Wear - Check....435
  Parking Brake - Test....438
  Parking Brake Control - Adjust....439
KENR8415 - Troubleshooting (120K and 120K Series 2 Motor Graders Air System and Brakes)....441
  General Information....442
  Machine Preparation for Troubleshooting....443
  Visual Inspection....446
  Operational Checks....447
  Air System and Brakes....449
KENR8416 - Specifications (120K and 120K Series 2 Motor Graders Power Train)....452
  Torsional Coupling....454
  Magnetic Screen (Transmission)....455
  Gear Pump (Transmission Charging and Scavenge)....458
  Relief Valve (Cooler Bypass)....460
  Oil Filter (Transmission)....461
  Governor Control....464
  Clutch Control (Modulation)....466
  Transmission Case....468
  Transmission....474
  Transmission Control Valve....478
  Selector and Pressure Control Valve....481
  Solenoid Valve (Transmission Clutch)....490
  Toggle Switch (Ground Level Shutdown)....493
  Speed Sensor (Transmission Intermediate)....494
  Speed Sensor (Transmission Output)....495
  Temperature Sensor (Transmission Oil)....496
  Drive Shaft....497
  Differential and Bevel Gear....498
  Solenoid Valve (Differential Lock)....506
  Final Drive....507
  Tandem and Cover....509
  Drive Chain....510
  Case and Frame....511
  Rollover Protective Structure (ROPS) - If Equipped SMCS - 7325....513
  Fuel Tank....515
  Window Wipers....517
  Window Washer....520
  Air Conditioner....521
  Battery....524
  Muffler....525
  Wheel and Mounting....527
  Wheel Group....528
KENR8437 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Engine Supplement)....530
  Battery - Remove and Install....531
  Engine Enclosure (Hood) - Remove....534
  Engine Enclosure (Hood) - Install....537
  Air Cleaner - Remove and Install....540
  Turbocharger - Remove and Install....542
  Muffler - Remove and Install....544
  Alternator - Remove and Install....547
  Engine Support (Front) - Remove and Install....549
  Air Compressor - Remove and Install....554
  Refrigerant Compressor - Remove and Install....558
  Engine Oil Filter Base - Remove....563
  Engine Oil Filter Base - Disassemble....566
  Engine Oil Filter Base - Assemble....568
  Engine Oil Filter Base - Install....570
  Engine Oil Cooler - Remove and Install....572
  Fuel Priming Pump - Remove and Install....577
  Water Pump - Remove....579
  Water Pump - Install....583
  Water Separator and Fuel Filter (Primary) - Remove and Install....586
  Fuel Filter (Secondary) and Fuel Filter Base - Remove and Install....588
  Electric Starting Motor - Remove and Install....590
  Refrigerant Condenser - Remove and Install....592
  Radiator Guard and Support; Aftercooler; and Radiator - Remove....597
  Aftercooler - Remove and Install....601
  Radiator - Remove and Install....607
  Radiator Guard and Support; Aftercooler; and Radiator - Install....614
  Engine - Remove....617
  Engine - Install....625
KENR8438 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Power Train)....632
  Duo-Cone Conventional Seals - Install....634
  Wheel and Tire (Rear) - Remove and Install....646
  Drive Chain - Remove....653
  Drive Chain - Install....658
  Service Brake (Wheel Spindle) - Remove....663
  Service Brake (Wheel Spindle) - Disassemble....666
  Service Brake (Wheel Spindle) - Assemble....676
  Service Brake (Wheel Spindle) - Install....687
  Tandem and Cover - Remove and Install....690
  Drive Sprocket - Remove and Install....697
  Final Drive - Remove....700
  Final Drive - Disassemble....702
  Final Drive - Assemble....712
  Final Drive - Install....722
  Transmission Oil Filter Base - Remove....724
  Transmission Oil Filter Base - Disassemble....726
  Transmission Oil Filter Base - Assemble....728
  Transmission Oil Filter Base - Install....730
  Gear Pump (Transmission Charging and Scavenge) - Remove....732
  Gear Pump (Transmission Charging and Scavenge) - Disassemble....736
  Gear Pump (Transmission Charging and Scavenge) - Assemble....740
  Gear Pump (Transmission Charging and Scavenge) - Install....745
  Transmission Oil Cooler - Remove....749
  Transmission Oil Cooler - Install....752
  Transmission Control Valve - Remove....755
  Transmission Control Valve - Disassemble....760
  Transmission Control Valve - Assemble....776
  Transmission Control Valve - Install....792
  Transmission - Remove....797
  Transmission - Disassemble....805
  Transmission - Assemble....833
  Transmission - Install....867
  Parking Brake - Remove....875
  Parking Brake - Disassemble....879
  Parking Brake - Assemble....884
  Parking Brake - Install....889
  Drive Shaft - Remove and Install....892
  Differential Lock Valve - Remove and Install....896
  Differential and Bevel Gear - Remove....899
  Differential and Bevel Gear - Disassemble....908
  Differential and Bevel Gear - Assemble....923
  Differential and Bevel Gear - Install....945
  Wheel and Tire (Front) - Remove and Install....954
  Front Axle - Remove....959
  Front Axle - Install....965
  Wheel Spindle - Remove....971
  Wheel Spindle - Install....979
  Wheel Spindle and Wheel Spindle Housing - Remove....986
  Wheel Spindle and Wheel Spindle Housing - Install....995
KENR8439 - Disassembly and Assembly (120K and 120K Series 2 Motor Graders Machine Systems)....1002
  Machine Preparation for Disassembly and Assembly....1005
  Duo-Cone Conventional Seals - Install....1007
  Guards - Remove and Install....1019
  Hydraulic Tank and Filter - Remove and Install....1023
  Pump Drive Shaft - Remove and Install....1031
  Piston Pump (Hydraulic and Steering) - Remove....1035
  Piston Pump (Hydraulic and Steering) - Disassemble....1040
  Piston Pump (Hydraulic and Steering) - Assemble....1050
  Piston Pump (Hydraulic and Steering) - Install....1060
  Combination Valve - Remove....1064
  Combination Valve - Disassemble....1068
  Combination Valve - Assemble....1076
  Combination Valve - Install....1085
  Bank Valve - Remove....1088
  Bank Valve - Disassemble - Bank Valve with out Detent....1099
  Bank Valve - Disassemble - Bank Valve with Hydraulic Detent....1106
  Bank Valve - Disassemble - Bank Valve with Mechanical Detent....1114
  Bank Valve - Assemble - Bank Valve with out Detent....1121
  Bank Valve - Assemble - Bank Valve with Mechanical Detent....1128
  Bank Valve - Install....1135
  Accumulator (Blade Cushion) - Remove and Install....1146
  Solenoid Valve (Blade Cushion) - Remove and Install....1150
  Blade Lift Cylinder - Remove and Install....1156
  Sideshift Cylinder - Remove and Install....1166
  Centershift Cylinder - Remove and Install....1178
  Blade Tip Cylinder - Remove and Install....1187
  Blade - Remove....1194
  Blade - Install 1....1201
  Blade - Install 2....1204
  Circle - Remove....1209
  Circle - Install....1225
  Drawbar - Remove....1243
  Drawbar - Install....1252
  Gerotor Motor (Circle Drive) - Remove....1262
  Gerotor Motor (Circle Drive) - Disassemble....1264
  Gerotor Motor (Circle Drive) - Assemble....1270
  Gerotor Motor (Circle Drive) - Install....1275
  Circle Drive - Remove....1277
  Circle Drive - Disassemble....1282
  Circle Drive - Assemble....1292
  Circle Drive - Install....1303
  Swivel - Remove....1308
  Swivel - Disassemble....1312
  Swivel - Assemble....1319
  Swivel - Install....1325
  Solenoid Valve (Centershift Lock) - Remove and Install....1328
  Centershift Lock Bar and Bushings - Remove....1332
  Centershift Lock Bar and Bushings - Install....1338
  Centershift Lock - Remove....1346
  Centershift Lock - Disassemble....1350
  Centershift Lock - Assemble....1353
  Centershift Lock - Install....1356
  Blade Lift Arm - Remove....1361
  Blade Lift Arm - Install....1369
  Articulation Cylinder - Remove and Install....1378
  Ripper Lift Cylinder - Remove and Install....1387
  Ripper - Remove....1395
  Ripper - Install....1406
  Tie Rod (Steering) - Remove and Install....1417
  Wheel Lean Bar - Remove and Install....1420
  Wheel Lean Arm and Axle Bushings - Remove....1428
  Wheel Lean Arm and Axle Bushings - Install....1436
  Wheel Lean Cylinder - Remove and Install....1444
  Steering Cylinder - Remove and Install....1453
  Metering Pump (Steering) - Remove and Install....1463
  Bottom Guard - Remove and Install....1478
  Air Dryer - Remove and Install....1481
  Air Tank - Remove and Install....1485
  Air Control Valve (Service Brake) - Remove....1489
  Air Control Valve (Service Brake) - Disassemble....1493
  Air Control Valve (Service Brake) - Assemble....1500
  Air Control Valve (Service Brake) - Install....1507
  Air Control Valve (Parking Brake) - Remove....1510
  Air Control Valve (Parking Brake) - Disassemble....1515
  Air Control Valve (Parking Brake) - Assemble....1517
  Air Control Valve (Parking Brake) - Install....1519
  Window Wiper and Wiper Motor (Front) - Remove and Install....1525
  Window Wiper and Wiper Motor (Rear) - Remove and Install....1535
  Governor Control - Remove and Install....1541
  Seat - Remove and Install....1543
  Cab - Remove....1545
  Cab - Install....1553
  Evaporator Coil and Heater Coil - Remove and Install....1563
  Blower Motor (Air Conditioner and Heater) - Remove and Install....1576
  Fuel Tank - Remove....1581
  Fuel Tank - Install....1586
  Front Frame from Rear Frame (Articulating Hitch) - Separate....1590
  Front Frame to Rear Frame (Articulating Hitch) - Connect....1607
UENR5014 - Schematic (12K, 120K, 140K, and 160K Motor Grader Electrical System)....1623
UENR7717 - Schematic (12K, 120K, 140K, and 160K Motor Grader Electrical System)....1625
  Features....1625
  Cover Page....1627
  Information....0
    Component Location....1628
    Connector Location....1629
    Specification and Related Manuals....1630
  Schematic....1631
  Machine Views....0
    Cab Below LH....1632
    Cab Below RH....1633
    Cab Bottom View....1634
    Cab Inside View....1635
    Chassis....1636
    Dashboard....1637
    Engine LH....1638
    Engine RH....1639
    Engine Top View....1640
    Headliner....1641
    Radiator....1642
    Shift Console....1643
    Transmisson....1644

EXCERPT:
1) Hydraulic tank
(2) Filter element
(3) Bypass valve
(AA) Implement return port
(BB) Case drain return port
(CC) Secondary steering port
(DD) Implement suction port
Hydraulic tank (1) is located behind the operator's cab. The oil reservoir is not vented. The oil reservoir contains a reverse flow element. Pressure is relieved when the cap is loosened. Secondary steering suction port (CC) and implement suction port (DD) provide outlets for the oil. These outlets flow to the implement and steering pump and the secondary steering pump. Case drain return port (BB) and implement return port (AA) combine the oil into the manifold. The manifold routes the oil through the bottom of the filter element and inside of the filter element. The filter element is positioned below the oil level in order to reduce turbulence.
If the filter element becomes full of debris, oil cannot pass through the filter element. The restriction to oil flow causes a pressure increase which opens bypass valve (3). A pressure of 35 kPa (5 psi) will cause the bypass valve to open. Now, the oil is allowed directly into hydraulic tank (1). When oil bypasses filter element (2), debris in the oil will cause damage to other system components. Correct maintenance must be used in order to make sure that the filter element does not stop the flow of clean oil to the hydraulic system.
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Caterpillar 120K & 120K Series 2 Motor Graders Factory Service & Shop Manual