2004 Komatsu PC78MR-6 Excavator Service Manual (P/N SEBM030602)
Komatsu Models Covered & Key Technical Specifications
Models: PC78MR-6
Sub-models / Variants: Steel shoe spec, Road liner spec, Rubber shoe
Model Years: 2004
Serial Numbers: 1001 and up
Technical Data:
- Engine: Komatsu S4D95LE-3-A, 4-cycle, water-cooled, in-line, direct injection
- Displacement: 3.26 L
- Rated output: 40.5 kW (54.0 HP) at 1,850 rpm
- Operating weight: 8,270–8,300 kg
- Travel speeds: 2.8 km/h (Low), 4.2 km/h (High)
- Swing speed: 10.0 rpm
- Hydraulic pump type: Variable-capacity piston pump × 1, Gear pump × 2
- Bucket capacity: 0.28 m³
Komatsu Manual Features & Content Preview
- Original OEM publication SEBM030602, printed in Japan, dated May 2004
- Documents the S4D95LE-3-A engine variant and associated control valve assemblies for serial numbers 1001 and up
- Contains 583 pages of factory-level technical specifications, maintenance standards, and hydraulic system diagrams
- Covers Steel shoe, Road liner, and Rubber shoe undercarriage configurations
- Features comprehensive exploded-view diagrams of the hydraulic pump, travel motor, control valve, and swing machinery
- Provides torque specs, fluid capacities, and pressure thresholds for quick shop-floor reference
Component and System Documentation
This Komatsu PC78MR-6 workshop manual details the structure and function of the entire hydraulic system. Mechanics gain clear insights into the variable-capacity piston pumps and gear pumps. Dedicated chapters cover the testing and adjusting of travel motors, swing machinery, and the multi-control valve. The documentation also outlines exact maintenance standards for track frames, idlers, and rollers. Technicians will find precise guidance for component assembly parameters, with specific sections breaking down the PPC lock solenoid valve, brake accumulators, and various EPC valves. Please note that while this text provides excellent reference data for troubleshooting, you must always consult a certified technician before initiating any heavy equipment service to ensure workplace safety.
Specification and Reference Data
Accurate reference data is critical for daily workshop operations. This publication lists comprehensive torque tables for metric bolts, flared nuts, split flange bolts, and O-ring boss piping joints. Factory hydraulic specifications for the PC78MR-6 are set at 26.5 MPa (270 kg/cm²) for work equipment and travel circuits. The swing and blade circuits operate at a distinct 21.1 MPa (215 kg/cm²). The manual also details exact system fluid requirements, specifying a 10.5-liter cooling system and a 120-liter hydraulic tank capacity.
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