Kubota U35S, U35-3S, U35-3, U35-3S2, KX91-3S, KX91-3, KX101-3, and KX91-3S2 Workshop Manual — 97899-61520

About this manual

Kubota published this Workshop Manual for the U35S, U35-3S, U35-3, U35-3S2, KX91-3S, KX91-3, KX101-3, and KX91-3S2 excavator models. It brings the documented service and technical-reference material for those named excavators into a single publication.

The manual is especially useful for work that crosses electrical and hydraulic systems: it includes electrical troubleshooting, alongside hydraulic diagrams, pressure-test evidence, and valve-adjustment information.

Use the Manual Contents below to check that the exact repair, inspection, or maintenance procedure you need is included in this publication.

Manual details

Manufacturer

Kubota

Manual type

Workshop Manual

Models

U35S, U35-3S, U35-3, U35-3S2, KX91-3S, KX91-3, KX101-3, and KX91-3S2

Document number

97899-61520

Publication year

2009

Language

English

Page count

958

Product highlights

Electrical systems

The manual includes wiring diagrams and electrical troubleshooting.

Hydraulic systems

The manual includes hydraulic circuit diagrams, hydraulic pressure-test material, and hydraulic valve-adjustment material.

Diagnostics

The manual includes diagnostic service-mode information and sensor-testing information.

Specifications and settings

The manual includes reference information for torque specifications, wear limits, and dimensions.

Special tools

A special-tools section is included.

Manual contents

Use these source headings to locate the task or system you need in the PDF.

• WSM_L1 — p. 1
  • CONTENTS — p. 3
  • I.GENERAL — p. 5
    • A. BODY AND ENGINE IDENTIFICATION MARKS — p. 7
    • B. SAFETY PRECAUTIONS FOR SERVICING, DISASSEMBLY AND REASSEMBLY — p. 9
      • a. Safety Measures before Starting Work — p. 9
      • b. Safety Measures during Work — p. 9
      • c. Preparation for Disassembly — p. 10
      • d. Precautions for Disassembly and Reassembly — p. 10
    • C. IMPORTANT SAFETY PROCESS AND CRITICAL FUNCTIONAL PROCESS — p. 13
      • a. Essential Adhesives — p. 13
      • b. Important Safety Process — p. 13
      • c. Important Critical Functional Process — p. 13
    • D. IMPORTANT INSPECTION ITEMS AFTER REASSEMBLING — p. 15
    • E. SERVICING FUNDAMENTALS — p. 17
      • a. Items for Servicing — p. 17
      • b. O-ring, Oil Seal, Circlip and Roll Pin — p. 19
      • c. Piping — p. 21
    • F. MAINTENANCE INTERVALS — p. 27
      • a. KTC, KCL, KTA-Version — p. 27
      • b. EU (KE, KBM, KUK)-Version — p. 28
      • c. Maintenance Intervals Using CF Class Engine Oil — p. 29
      • d. Hydraulic Oil Check for Machines with Hydraulic Breakers — p. 31
    • G. WATER AND OIL QUANTITY — p. 33
    • H. RECOMMENDED OIL — p. 35
    • I. PERIODIC REPLACEMENT OF IMPORTANT PARTS — p. 37
    • J. MAINTENANCE PARTS — p. 39
    • K. SALES ENGINEERING INFORMATION — p. 41
      • a. Quick Feature Chart — p. 41
      • b. Feature Descriptions — p. 43
      • c. Minor Change New Feature (EU-Version: KX91-3a2, KX101-3a2, U35-3a2) — p. 51
      • d. The Minor Change List of KX91-3S2 and U35S2 (KTC, KCL, KTA-Version) — p. 58
  • II.MACHINE BODY (Mechanism Section) — p. 61
    • A. FRONT ATTACHMENT — p. 63
      • a. Greasing Points — p. 63
      • b. Bucket Interchangeability — p. 64
    • B. COMPONENT INTERCHANGEABILITY — p. 65
      • a. Bucket Interchangeability — p. 65
      • b. Arm — p. 67
      • c. Installing Direction of Dust Seal — p. 68
      • d. Installation of Bushing and Thrust Collar on the Swing Bracket — p. 68
      • e. Installing Pin, Bush and Shim (1): U35S — p. 69
      • f. Installing Pin, Bush and Shim (2): U35S — p. 70
      • g. Installing Pin, Bush and Shim of Bucket: U35S — p. 71
      • h. Installing Local Bucket: U35S — p. 72
      • i. Swivel Frame — p. 73
      • j. Swivel Bearing — p. 74
    • C. TRACK FRAME AND COMPONENTS — p. 75
      • a. Tension Spring Pre-set Length — p. 75
      • b. Additional Parts to Change from Rubber Track to Iron Track — p. 75
      • c. Track Tension Adjustment — p. 76
      • d. Grease Tension Cylinder, L — p. 77
      • e. Drive Sprocket — p. 78
      • f. Rubber Track — p. 79
      • g. Iron Track — p. 80
  • II.MACHINE BODY (Service Section) — p. 81
    • A. SPECIFICATIONS — p. 83
      • a. Machine Weight — p. 83
      • b. Machine Specifications — p. 84
      • c. Lever Stroke and Operating Force — p. 86
      • d. Dimensions of Parts — p. 88
      • e. Quality Specifications — p. 100
    • B. FRONT ATTACHMENT — p. 109
      • a. Parts Designation — p. 109
      • b. Exchange of Bucket (Kubota Japan Bucket) — p. 112
      • c. Exchange of Bucket Teeth and Side Cutter — p. 113
      • d. Installing Direction of Dust Seal — p. 114
      • e. Installation of Thrust Collar on the Swing Bracket — p. 115
      • f. Pin Bushing and Shims (1): KX91-3S2, U35S2 — p. 116
      • g. Pin Bushing and Shims (2): KX91-3S2, U35S2 — p. 117
      • h. Pin Bushing and Shims (3): KX91-3S2, U35S2 — p. 118
      • i. Pin Bushing and Shims (4): KX91-3S2, U35S2 — p. 119
      • j. Pin Bushing and Shims (5): KX91-3S2, U35S2 — p. 120
      • k. Installing Direction of Fixing Pin Bolts — p. 121
      • l. Front Hoses and Clamps — p. 122
      • m. Apply Grease (1) — p. 123
      • n. Apply Grease (2) — p. 124
    • C. UPPER STRUCTURE — p. 125
      • a. Swivel Bearing — p. 125
      • b. Traveling Lever Link — p. 126
      • b-1. Traveling Lever Link: KX91-3S2, U35S2 — p. 127
      • c. Traveling Lever Adjustment — p. 128
      • c-1. Traveling Lever Adjustment: KX91-3S2, U35S2 — p. 129
      • d. Traveling Lever Lock — p. 130
      • e. Accelarator Lever — p. 132
      • f. Dozer Lever — p. 133
      • f-1. Blade Lever: KX91-3S2, U35S2 — p. 134
      • g. Swing Pedal — p. 135
      • g-1. Swing Pedal: KX91-3S2, U35S2 — p. 136
      • h. Pilot Lever, Canopy Type: KX91-3S2, U35S2 — p. 137
      • h-1. Pilot Lever, Cab Type: KX91-3S2, U35S2 — p. 138
      • i. Location of Links for Each Operation — p. 139
      • i-1. Control Link to Control Valve: KX91-3S2, U35S2 — p. 140
      • j. Limit Switch: KX91-3S2, U35S2 — p. 141
      • k. Accel Cable, AI Motor: KX91-3S2, U35S2 — p. 142
      • l. Engine Stop Cable — p. 144
      • m. Seat and Seat Belt — p. 145
      • n. Weight Installation — p. 147
    • D. UNDER CARRIAGE — p. 149
      • a. Track Tension Device — p. 149
      • b. Crawler Installation — p. 150
      • c. Track Roller and Upper Roller Installation — p. 151
    • E. ROPS/FOPS CAB — p. 153
      • a. Cab Mounting — p. 153
      • b. Cab Name Plate — p. 154
      • c. Heater Hose — p. 155
      • d. Seat and Control Levers — p. 156
      • e. Step Plate and Cushion — p. 157
      • f. Defroster — p. 158
      • g. Cab Sealing — p. 159
      • h. Decal — p. 160
      • i. Wiper Motor — p. 161
      • j. Cab Harness — p. 162
      • k. Cab Electric Circuit Diagram — p. 163
      • l. Cab Glass Replacement Procedure — p. 164
    • F. ROPS/FOPS CANOPY — p. 175
      • a. Canopy Mounting — p. 175
      • b. Canopy Lamp — p. 176
      • c. Canopy Harness — p. 177
    • G. DECAL — p. 179
      • a. List of Decal — p. 179
      • b. Location of Decal (1) — p. 181
      • c. Location of Decal (2) — p. 182
      • d. Location of Decal (3) — p. 183
      • e. Location of Decal (4) — p. 184
      • f. Location of Decal (5) — p. 185
      • g. Location of Decal (6) — p. 186
      • h. Location of Decal (7) — p. 187
    • H. SOUND ABSORBER AND TRIM — p. 189
      • a. List (1) — p. 189
      • b. List (2) — p. 192
      • c. Sound Absorber & Trim (1) — p. 194
      • d. Sound Absorber & Trim (2) — p. 195
      • e. Sound Absorber & Trim (3) — p. 196
      • f. Sound Absorber & Trim (4) — p. 197
      • g. Sound Absorber & Trim (5) — p. 198
      • h. Sound Absorber & Trim (6) — p. 199
      • i. Sound Absorber & Trim (7) — p. 200
    • I. REMOVING THE CONTROL VALVE BONNET — p. 201
  • III.ENGINE (Mechanism Section) — p. 209
    • A. ENGINE — p. 211
      • a. General — p. 211
      • b. Engine Specifications — p. 213
      • c. Performance Curve — p. 217
    • B. SPECIFICATIONS & FEATURES — p. 223
      • a. Specifications: D1503-M — p. 223
      • b. Features — p. 223
    • C. FUEL INJECTION PUMP — p. 225
      • a. Structure — p. 225
      • b. Precaution of Removing Reassembly — p. 226
    • D. RADIATOR FAN & COUPLING FLANGE — p. 231
      • a. Fan Belt Tension Adjustment — p. 231
      • b. Alternator Mounting Bolt Torque: — p. 231
      • c. Temp. Sensor Tightning Torque: — p. 231
      • d. Fan Flange Bolt Tightning Torque: — p. 231
      • e. Bolt Tightning Torque of Coupling Flange — p. 231
      • f. Coupling Flange — p. 232
    • E. OTHER PARTS — p. 233
      • a. Fuel Filter — p. 233
      • b. Air Filter — p. 234
      • c. Thermostat — p. 235
    • F. KX91-3S2 MINOR CHANGE — p. 237
      • a. Engine Installation (1) — p. 237
      • b. Engine Installation (2) — p. 238
      • c. Engine Installation (3) — p. 239
      • d. Engine Mount (1) — p. 240
      • e. Engine Mount (2) — p. 241
      • f. Air Cleaner — p. 242
      • g. Radiator (1) — p. 243
      • h. Engine Radiator (2) — p. 244
      • i. Muffler — p. 245
      • j. Pump Coupling — p. 246
      • k. Fuel Tank — p. 247
      • l. Around the Fuel Tank — p. 248
      • m. Fuel Hose (1) — p. 249
      • n. Fuel Hose (2) — p. 250
      • o. Fuel Hose (3) — p. 251
      • p. Add-on Fuel Bypass Circuit — p. 252
  • IV.HYDRAULIC SYSTEM (Mechanism Section) — p. 365
    • A. FEATURES OF HYDRAULIC SYSTEM — p. 367
    • B. HYDRAULIC SYSTEM SPECIFICATIONS — p. 369
    • C. MAIN PUMP — p. 371
      • a. Structures & Specifications — p. 371
      • b. Performance Curve — p. 372
    • D. CONTROL VALVE — p. 375
      • a. Specifications — p. 375
      • b. General View of Control Valve — p. 377
      • c. Control Valve Circuit Diagram — p. 379
      • d. Control Valve Sectional View — p. 380
      • e. Arm Regeneration Circuit — p. 386
      • f. Oil Flow of Lock Valve — p. 387
      • g. Function of Lock Valve (Anti-Drift Valve) — p. 391
      • h. Relief Valve/Anti-Cavitation Valve — p. 392
      • i. Straight Travel Circuit — p. 393
      • j. Other Functions — p. 394
    • E. PILOT VALVE — p. 395
      • a. Structure & Specifications — p. 395
      • b. Pilot Valve Control Diagram — p. 397
    • F. SWIVEL MOTOR — p. 399
      • a. Structure & Specifications — p. 399
      • b. Function of Negative Brake — p. 402
      • c. Function of Valve Section — p. 403
    • G. ROTARY JOINT (SWIVEL JOINT) — p. 405
    • H. TRAVEL MOTOR — p. 407
      • a. Structure & Specifications: KTC, KCL, KTA-Version — p. 407
      • b. Operation of Piston Motor — p. 409
      • c. Function of Shockless Valve — p. 410
      • d. Travel Motor: KX91-3S, KX91-3S2, U35S, U35S2, U35-3S: PP-Version — p. 412
      • e. The Wheel Motor with the Negative Brake: KX91-3S2, U35S2, U35-3S2 — p. 415
      • f. Travel Motor History (3 Ton Class) — p. 417
      • g. KX91-3/S/S2, U35S/S2, Travel Motor Changing — p. 425
    • I. OTHER COMPONENTS — p. 427
      • a. Change Valve with Accumulator: EU-Version — p. 427
      • b. Pilot Filter — p. 431
      • c. Return Filter — p. 432
      • d. Suction Strainer — p. 432
      • e. Proportional Control Solenoid Valve (S/P Valve) — p. 433
      • f. Accumulator Installation: KX91-3S, U35S, U35-3S (KTA) — p. 441
    • J. HYDRAULIC CIRCUIT DIAGRAM — p. 443
      • a. Hydraulic Circuit Diagram — p. 443
      • b. Hydraulic Components Layout — p. 456
  • IV.HYDRAULIC SYSTEM (Service Section) — p. 457
    • A. TROUBLESHOOTING — p. 459
      • a. Common Circuit — p. 459
      • b. Front Attachment — p. 461
      • c. Swivel Circuit — p. 464
      • d. Travel Circuit — p. 466
    • B. SPECIFICATIONS — p. 467
      • a. Relief Valve Pressure Setting — p. 467
      • b. Pump — p. 469
      • c. Cylinder — p. 471
      • d. Swivel Performance — p. 475
      • e. Traveling Performance — p. 477
    • C. TESTING — p. 481
      • a. Testing Instruments & Special Tools — p. 481
      • b. Pump Flow — p. 483
      • c. Pilot Pressure — p. 484
      • d. Main Relief Valve — p. 486
      • e. Overload Relief Valve — p. 488
      • f. Swivel Brake Valve Pressure — p. 490
      • g. Traveling Motor Drain Amount — p. 492
      • h. Swivel Motor Drain Amount — p. 493
      • i. Swivel Motor Block Performance — p. 494
      • j. Traveling Motor Block Performance — p. 495
      • k. Operating Speed — p. 496
      • l. Straight Travel Performance — p. 498
      • m. Cylinder Natural Fall Amount — p. 499
      • n. Control and Traveling Lever Operating Force — p. 499
      • o. Lever Stroke — p. 499
    • D. DISASSEMBLING AND ASSEMBLING — p. 501
      • a. Coupling Flange — p. 501
      • b. Pump — p. 502
      • c. Control Valve and Relief Valve — p. 528
      • d. Pilot Valve — p. 539
      • e. Swivel Motor (KTC, KCL, KTA-Version) — p. 555
      • f. Travel Motor: KX91-3, U35, U35-3 — p. 567
      • g. Travel Motor: Super Series (KX91-3S, U35S, U35-3S) — p. 587
      • h. Servicing of Valve Body and the Negative Brake — p. 596
      • i. Servicing the Motor’s Reduction Gear Case — p. 610
      • i. Servicing the Motor’s Reduction Gear Case — p. 622
      • j. Rotary Joint — p. 634
      • k. Cylinder (KE, KDG, KUK-version) — p. 637
      • l. Cylinder (KTC, KCL, KTA-version) — p. 649
      • m. Other Hydraulic Device — p. 661
      • n. Hose — p. 676
  • V.ELECTRICAL SYSTEM (Mechanism Section) — p. 715
    • A. KUBOTA INTELLIGENT CONTROL SYSTEM — p. 717
      • a. Development Concept of KICS — p. 717
      • b. Outline of Kubota ICS (Intelligent Control System) — p. 719
      • c. Operating Mode — p. 722
      • d. Service Mode Menues — p. 724
    • B. NEW AUTO IDLING (AI) CONTROL SYSTEM — p. 743
      • a. Purpose — p. 743
      • b. Auto Idle Function Mechanism — p. 743
      • c. New Auto Idling Modification — p. 744
      • d. Idle-up Control — p. 751
      • e. Compressor Control — p. 752
      • f. Engine Speed Sensor — p. 753
      • g. Governor Sensor — p. 754
      • h. Accel Sensor (Electric Accelerator) — p. 755
      • i. AI Pressure Switch — p. 756
    • C. MAIN COMPONENT’S FUNCTION — p. 757
      • a. Auto Release Function — p. 757
      • b. Travel Hi-speed Control Circuit — p. 762
      • c. Meter Panel (Controller Unit) — p. 763
    • D. FAILURE DIAGNOSIS — p. 765
    • E. SERVICE MODE FLOW CHART — p. 779
    • F. FINGER CONTROL SERVICE PORT SYSTEM — p. 781
      • a. Feature and Purpose — p. 781
      • b. Outline of Control System — p. 782
      • c. Hydraulic Circuit Diagram — p. 784
      • d. Knob Structure and Function — p. 785
      • e. Initial Settings of the Knob — p. 791
      • f. S/P Valve Start Point Setting — p. 793
      • g. Manual Feeling Setting — p. 799
      • i. Proportional Control Solenoid Valve (S/P Valve) — p. 810
      • j. Other Controls — p. 815
    • G. NEW AUXILIARY OIL FLOW CONTROL — p. 817
      • a. System Overview — p. 817
      • b. Service Port Operation Method — p. 819
      • c. Proportional Solenoid Valve — p. 824
      • d. Amplifier Unit — p. 827
    • H. COUPLERS, ELECTRICAL CIRCUIT & WIRING DIAGRAM — p. 829
      • a. Couplers — p. 829
      • b. Component Layout — p. 830
      • c. Service Mode Flow Chart — p. 831
      • d. Circuit Wiring Diagram — p. 832
      • e. Circuit Function Diagram — p. 834
  • V.ELECTRICAL SYSTEM (Service Section) — p. 841
    • A. TROUBLESHOOTING — p. 843
      • a. General — p. 843
      • b. Front Attachment — p. 851
      • c. Engine Electrical System — p. 853
      • d. Auto Idle System — p. 860
      • e. AI Version: AI Controller (Built-in Microcomputer) — p. 869
    • B. INSTALLATION OF WIREHARNESS (APPLIED MODEL: MAINLY KX91-3S2) — p. 873
      • a. Precautions — p. 873
      • b. Harness Clamp (1) — p. 874
      • c. Harness Clamp (2) — p. 875
      • d. Harness Clamp (3) — p. 876
      • e. Harness Clamp (4) — p. 877
      • f. Reference Photos — p. 878
      • g. Service Port Solenoid Valve — p. 879
      • h. Front Harness — p. 880
  • VI.OPTIONAL UNIT — p. 881
    • A. ANGLE BLADE — p. 883
      • a. Specifications — p. 883
      • b. Hydraulic Circuit Diagram — p. 885
      • c. Installation — p. 887
      • d. Swivel Joint (1) — p. 888
      • e. Swivel Joint (2) — p. 889
      • f. Control Valve — p. 890
      • g. High Pressure Hose — p. 891
      • h. Hose Connection — p. 892
      • i. Hose Installing Angle — p. 894
      • j. Control Lever — p. 895
      • k. Control Link — p. 896
      • l. Control Cables — p. 897
      • m. Blade Bushings — p. 898
      • n. Grease Points — p. 899
      • o. Decals — p. 900
      • p. Blade Cylinder Hose (1) — p. 901
      • q. Blade Cylinder Hose (2) — p. 902
      • r. Pilot Hose Clamp — p. 903
    • B. TELESCOPIC ARM — p. 905
      • a. Installation — p. 905
      • b. Hoses and Pipes — p. 906
      • c. Control Valve — p. 907
    • C. TRAVEL ALARM — p. 909
      • a. Installation — p. 909
      • b. Wireharness — p. 911
    • D. KTA-VERSION — p. 913
      • a. Actual Service Port Flow: KX91-3, KX91-3S, KTA-Version Only — p. 913
      • b. Breaker Performance Test Sample: KTA-Version Only — p. 919
    • E. KTC-VERSION, OPTIONAL KIT — p. 925
      • a. Installation Manual for Canopy Kit — p. 925
      • b. Working Light Installation Manual — p. 929
      • c. Installation Manual for Cabin Kit — p. 935
      • d. Item List of Heat Insulator Kit — p. 942
      • e. Installation Manual Auxiliary Relief Valve and Cylinder Mounting Bracket Kit — p. 945
      • f. STEEL CRAWLER KIT (Convert tracks from rubber to steel) — p. 950
  • Conversion Tables — p. 955

Capabilities

The source outline indexes servicing instructions, disassembly and assembly, maintenance tasks, checking and adjustment, mechanism explanations, and troubleshooting. Use these source-backed headings to locate the applicable task or system in the source PDF, then confirm model-specific notes, specifications, illustrations, and operating conditions at the relevant page before carrying out service work.

Keep the source's safety sequence, prerequisite steps, labels, units, configuration notes, and footnotes with the selected task; do not apply an isolated value outside the conditions stated in the manual.

Technical reference

Reference tables include torque settings, wear limits, and dimensions for service checks, adjustment work, and specification lookup. Use the values and conditions in the PDF for the applicable model and procedure.

• Service limits and settings: torque settings and wear limits.
• Machine specifications: dimensions.

Delivery

This manual is supplied as a digital PDF file and is available for instant download after purchase. No physical media is shipped.

References

Kubota Workshop Manual for Excavator, document code 97899-61520, PDF edition.