Komatsu PC78UU-6 / PC78US-6 Excavator Service Manual

Technical Scope and Features

• Covers 1998–2007 Komatsu PC78UU-6 and PC78US-6 hydraulic excavators, detailing both blade-equipped and blade-less configurations with various undercarriage options
• Official Komatsu publication SEBM025116, published October 2007
• Contains 47 exploded-view diagrams, 8 hydraulic circuit schematics, and 12 detailed torque specification tables
• File link appears in your order confirmation straight away
• Page spreads stay legible when printed at original size
• OCR text layer lets you jump to a torque spec by keyword
• This manual documents machine-specific serial number ranges starting from 22832 for the PC78UU-6 and 4001 for the PC78US-6

Component and Systems Documentation

The 1,027-page shop manual provides comprehensive technical reference data for the Komatsu PC78UU-6 and Komatsu PC78US-6 machines. The content is organized by functional group, starting with general safety precautions for maintenance and hoisting procedures. Key chapters cover the structure and function of the machine systems, including detailed walk-throughs of the power train, cooling assemblies, and the hydraulic circuits that drive the unit.

Additional documentation focuses on disassembly and assembly procedures for major components. Readers will find structural details regarding the swing machinery, center swivel joint, travel motors, and work equipment cylinders. The manual also includes extensive technical data for what an OEM service publication covers regarding adjustments and testing parameters.

Specification and Reference Values

Detailed tables provide critical reference values for maintenance and assembly tasks. Tightening torque values for standard metric bolts, flared nuts, split flange bolts, and O-ring boss joints are documented to ensure correct assembly. For hydraulic systems, the manual lists relief pressures and pressure settings for the work equipment, swing, and travel circuits. Fluid capacity specifications for the engine, swing machinery, and cooling system are provided for multiple serial number configurations. Engine performance, including rated power and fuel consumption data, is documented for the 4D95LE-2 and S4D95LE-3-A power plants.

Reference only — always consult a certified technician before performing service on this equipment. An official 1,027-page Komatsu OEM workshop manual covering the 1998–2007 PC78UU-6 and PC78US-6, documenting engine, hydraulic, electrical, and structural specifications for these excavator models.

Document Reference: SEBM025116, October 2007