Komatsu PC78US-8 Hydraulic Excavator Shop Manual SEN04543-03 – PDF Download

Description

Komatsu PC78US-8 Hydraulic Excavator Shop Manual – SEN04543-03

This Komatsu PC78US-8 Shop Manual is the full workshop reference for the PC78US-8 hydraulic excavator, serial number 15001 and up, fitted with the Komatsu SAA4D95LE-5 turbocharged, aftercooled diesel engine. Issued by Komatsu under document number SEN04543-03, it collects every section a technician needs – specification data, structure and function, standard values, testing and adjusting procedures, troubleshooting by failure code and symptom, disassembly and assembly instructions, and the hydraulic and electrical diagrams – into a single searchable-by-section PDF.

The PC78US-8 service manual is organised the way the factory workshop actually works: you diagnose with the failure code table and monitoring functions, verify with the standard value table and testing procedures, then repair using the disassembly and assembly chapters with their torques, coating materials and special tool references. Every actuator – boom, arm, bucket, blade, swing and travel – is covered end to end.

File Details

• Manual type: Shop Manual (Service / Workshop Manual)
• Brand: Komatsu
• Model: PC78US-8 Hydraulic Excavator
• Serial number: 15001 and up
• Engine: Komatsu SAA4D95LE-5
• Language: English
• Format: PDF
• Page count: 970 pages
• Document number: SEN04543-03
• Publication date: 2009

Chapters Covered

• 00 Index and Foreword
• 01 Specification
• 10 Structure, Function and Maintenance Standard
• 20 Standard Value Table
• 30 Testing and Adjusting
• 40 Troubleshooting
• 50 Disassembly and Assembly
• 90 Diagrams and Drawings

Foreword and General Information

Covers safety notices for the workshop, how to read the shop manual, the symbols used for weight, torque, coating, oil and drain points, explanation of maintenance standard terminology (standard size and tolerance, standard clearance, repair limit, allowable value, interference limit), correct handling of electric equipment and hydraulic components, handling of the engine connectors used on the SAA4D95LE-5, how to read electric wire codes, push-pull coupler disassembly, the standard tightening torque tables for bolts, nuts, split flanges, O-ring boss joints and hoses, and the metric/imperial conversion tables.

01 Specification

Specification dimension drawing with overall length, height, width, shoe width, tail swing radius, crawler length and gauge, working range diagram showing maximum digging reach, digging depth, digging height, dumping height and blade lift/drop, plus the machine specification tables, weight table for every major assembly, and the fuel, coolant and lubricant table with ambient-temperature recommendations and reservoir capacities.

10 Structure, Function and Maintenance Standard

The largest section of the PC78US-8 workshop manual. Covers the engine mount and PTO, cooling system, power train and swing circle and swing machinery, undercarriage and frame (track frame, idler cushion, idler, track roller, carrier roller, sprocket, track shoe), hydraulic system split into Part 1 (component layout, valve control, hydraulic tank and filter, hydraulic pump and LS/PC control), Part 2 (control valve, CLSS closed-centre load sensing, unload valve, merge-divider valve, LS bypass valve, boom regeneration, travel junction, pressure compensation valve), Part 3 (PPC valve, swing motor and brake valve, travel motor and brake valve, center swivel joint, solenoid valve, PPC accumulator, anti-drop valve, multi-control valve), work equipment and cylinders, cab air conditioner, and the full electrical system including electronic control functions, machine monitor, KOMTRAX and sensors.

20 Standard Value Table

Engine-related standard values (engine speed, exhaust gas colour, valve clearance, compression pressure, blow-by pressure, oil pressure, oil temperature, fan belt tension, air conditioner belt tension) and the chassis standard value table covering control lever stroke, play, operating effort, relief pressures for boom, arm, bucket, swing, blade and travel circuits, control circuit basic pressure, swing overrun, swing time, hydraulic drift, travel speed, travel deviation, internal leakage and work equipment speed.

30 Testing and Adjusting

Part 1 covers the special tools, engine speed testing, exhaust temperature, exhaust gas colour, valve clearance, compression pressure, blow-by pressure, engine oil pressure, fuel system handling and pressure testing, air bleeding, belt tension, swing circle bearing clearance, track shoe tension, work equipment and travel circuit relief pressures, swing and blade circuit pressures, control circuit basic pressure, PC control circuit pressure, PC-EPC output pressure, LS differential pressure and LS valve adjustment, solenoid valve output pressure, PPC valve output pressure, PPC lever play, hydraulic drift diagnosis, travel deviation adjustment, residual pressure release, oil leakage testing, air bleeding and mirror adjustment. Part 2 documents the special functions of the machine monitor. Part 3 covers the engine controller voltage circuit, preparation work for electrical troubleshooting, diode testing and the Pm Clinic service sheet.

40 Troubleshooting

The diagnosis section of the Komatsu PC78US-8 service manual – failure code table and fuse locations, general troubleshooting information, the connection table for connector pin numbers, and the T-branch box and T-branch adapter table. Failure codes are addressed individually across four parts, from engine controller lock cautions and CAN disconnection through to injector, rail pressure, boost pressure, throttle, PPC sensor and wiper/washer failure codes. Electrical system troubleshooting is covered in E-mode, hydraulic and mechanical symptoms in H-mode, and engine symptoms in S-mode, with the troubleshooting tables listing possible causes, standard values in the normal state and step-by-step checks.

50 Disassembly and Assembly

The hands-on repair section. General information, coating materials list, special tool list and sketches, then removal and installation or disassembly and assembly of the fuel supply pump, fuel injectors, engine front and rear seals, cylinder head, radiator, aftercooler, hydraulic oil cooler, engine and hydraulic pump assembly, fuel tank, travel motor and final drive, swing motor and swing machinery, swing circle, track roller, idler, recoil spring, track shoe, sprocket, revolving frame, counterweight, center swivel joint, hydraulic tank, hydraulic pump, control valve, PPC valves, hydraulic cylinders, work equipment and blade, cab and attachments, glass, floor frame, air conditioner unit, machine monitor, pump controller, engine controller and KOMTRAX terminal.

90 Diagrams and Drawings

Hydraulic circuit diagrams for the PC78US-8 blade specification, bladeless specification and EU specification, actuator attachment hydraulic circuit diagram, and the six-sheet electrical circuit diagram for the standard and EU specifications, plus the air conditioner unit electrical circuit diagram and the complete connector list with stereogram.

Why This Komatsu PC78US-8 Shop Manual Matters in the Workshop

The PC78US-8 is a compact-radius excavator, which means tight packaging, a hydraulic system running on Komatsu’s CLSS pressure-compensated architecture, and an electronic layer of pump, engine and monitor control that has to be understood before a fault can be diagnosed correctly. Guessing costs hours and parts. This Komatsu PC78US-8 PDF manual gives you the correct standard value before you judge a component, the correct failure-code logic before you swap a sensor, and the correct tightening torque and coating material before you close a joint.

The specification, standard value and testing and adjusting chapters together allow a real condition assessment of the machine – relief pressures, LS differential, PC-EPC output, travel deviation, hydraulic drift, blow-by and compression. The disassembly and assembly chapters allow complete overhauls of the hydraulic pump, control valve, swing and travel motors, cylinders and final drives, with weights, lifting points and special tools listed so the job can be planned before the machine is opened. The electrical troubleshooting chapters and connector tables allow genuine circuit diagnosis instead of parts substitution.

For an owner-operator running a single machine, this is the manual that turns a fault code on the monitor into a repair plan. For a workshop, it is the reference that keeps every PC78US-8 that comes through the door on the same factory numbers.

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Instant PDF Delivery

Your Komatsu PC78US-8 Hydraulic Excavator Shop Manual SEN04543-03 is delivered as an instant PDF download – no shipping, no waiting, no binder to lose. Read it on a laptop in the service truck, on a tablet on the machine, or print the pages you need for the job and keep the paper clean on the bench. The 970-page document is organised so you can jump straight to the section you need, whether that is a torque figure in the disassembly chapter, a relief pressure in the testing and adjusting chapter, or a failure code in the troubleshooting chapter.