Komatsu 870C Motor Grader SN 202775 UP Service Repair Workshop Manual

<h3>Komatsu 870C Motor Grader -- SN 202775 and Up</h3> <p>The Komatsu 870C motor grader represents Komatsu's commitment to the road construction and maintenance equipment segment, building upon decades of motor grader engineering heritage at their facilities. Motor graders are among the most skilled-operator-dependent machines on any job site, requiring precise coordination of blade angle, pitch, side shift, and circle rotation to achieve the finished grade specifications demanded by civil engineering projects. The 870C continues the lineage of Komatsu graders used on highway construction, mining road maintenance, snow removal, and fine-grading applications across continents.</p> <p>The "C" suffix in the model designation indicates the latest iteration in the 870 lineage, incorporating incremental improvements in operator cab ergonomics, hydraulic valve response, and emissions-compliant engine technology over the preceding 870B model. Units with serial number 202775 and higher include all factory engineering changes and component updates through that production cut point. The 870C is powered by a turbocharged Komatsu or Cummins diesel engine (depending on market configuration) delivering the high-torque output needed to pull a fully loaded 12- or 14-foot moldboard through packed aggregate and compacted soil at grading speeds.</p> <p>Motor grader uptime directly impacts project scheduling on road construction. A single day of grader unavailability can delay the entire earthwork sequence -- subgrade preparation, base course spreading, fine grading, and compaction all depend on the grader completing its task on schedule. Understanding the 870C's hydraulic system layout, blade control mechanisms, articulated frame steering, and power shift transmission service requirements enables equipment managers to maintain their graders proactively rather than reactively. This official Komatsu service manual is the definitive reference for all maintenance, repair, and diagnostic procedures.</p> <h3>SERVICE & REPAIR SCOPE</h3> <ul> <li><strong>Engine Service:</strong> Complete engine removal and installation, cylinder head overhaul procedures, fuel injection pump calibration and timing, turbocharger inspection and replacement, cooling system service including water pump and thermostat, and all scheduled maintenance item specifications.</li> <li><strong>Power Shift Transmission:</strong> Transmission removal from chassis, clutch pack wear measurement, valve body disassembly, planetary gear set inspection, sealing ring replacement, and transmission oil specification (Komatsu genuine or compatible equivalent).</li> <li><strong>Articulated Frame Steering:</strong> Steering cylinder seal kit installation, steering pin bushing inspection and replacement, frame hinge bearing clearance measurement, steering accumulator pre-charge verification, and steering system flow testing at designated test ports.</li> <li><strong>Circle & Blade Control:</strong> Circle drive motor overhaul, circle center pivot bearing replacement, blade pitch cylinder service, side shift rack inspection, moldboard cutting edge bolt specification, and circle rotation backlash adjustment.</li> <li><strong>Hydraulic System:</strong> Main hydraulic pump flow and pressure testing, valve spool inspection, hydraulic line connection torque specifications, hydraulic fluid contamination analysis procedures, and hydraulic filter element change with system bleed protocol.</li> <li><strong>Brake System:</strong> Service brake disc and pad inspection, wet brake pack replacement (if equipped), parking brake cable adjustment, and brake fluid specification and bleeding procedures for hydraulic circuits.</li> <li><strong>Electrical System:</strong> Alternator output testing, starter motor removal and servicing, all switch continuity testing, wiring harness inspection and connector pin-out reference, and monitor panel warning lamp circuit diagnostics.</li> <li><strong>Axle & Drive:</strong> Front axle inspection and overhaul if equipped, rear tandem drive inspection, planetary final drive bearing preload, axle shaft seal replacement, and oil specification for each housing.</li> </ul> <h3>TECHNICAL SPECIFICATIONS</h3> <p><strong>Model:</strong> Komatsu 870C Motor Grader<br> <strong>Serial Numbers:</strong> 202775 and UP<br> <strong>Engine:</strong> Turbocharged Komatsu/Cummins diesel (market dependent)<br> <strong>Moldboard:</strong> 12-foot or 14-foot (configuration dependent)<br> <strong>Transmission:</strong> Power Shift, multiple forward and reverse speeds<br> <strong>Steering:</strong> Articulated frame steering with hydraulic assist<br> <strong>Blade Controls:</strong> Hydraulic circle drive with blade angle, pitch, and side shift</p> <h3>DIAGNOSTIC INFORMATION</h3> <p>Troubleshooting procedures follow Komatsu's systematic diagnostic methodology: start with operator observations and warning indicators, verify system pressures at designated test ports, isolate circuits by block valve manipulation, and narrow to component level using electrical and mechanical testing. The manual includes hydraulic circuit diagrams with test port locations, electrical schematics with measurement specifications, and decision-tree diagrams for the most common operator-reported symptoms including hydraulic drift, steering play, and blade positioning inaccuracy.</p> <h3>ILLUSTRATIONS & DIAGRAMS INCLUDED</h3> <p>Full assembly sectional drawings of engine-to-transmission interface, power shift transmission cross-section, steering cylinder and frame hinge, circle drive mechanism, moldboard and blade mounting, and hydraulic valve block assemblies. Complete electrical wiring diagrams with component location codes. Hydraulic system circuit schematics with all pump, valve, cylinder, and motor interconnections shown.</p> <h3>COMPATIBILITY</h3> <p>This service manual applies to the Komatsu 870C Motor Grader with serial numbers 202775 and higher. Not applicable to earlier 870A or 870B models without serial number cross-reference, or to the smaller 830/850 series or the larger 875 graders, which have different frame, hydraulic, and powertrain architectures.</p> <h3>FILE PROPERTIES</h3> <p>High-quality searchable PDF document in English. Instant digital download -- no shipping delays. Access from any device at the job site or in the repair shop. Print individual service procedures for technicians. Searchable text enables rapid location of any part number, torque specification, or diagnostic step.</p>