2000 Komatsu PC128UU-1, PC128US-1 Excavator Shop Manual (P/N SEBM009805)

Komatsu shop manual SEBM009805, printed in August 2000, covers the PC128UU-1 and PC128US-1 hydraulic excavators within the serial-number ranges listed above.

• Engine service: Cylinder-head and fuel-injection-pump removal and installation, valve-clearance adjustment, injection-timing checks, and oil-pressure and blow-by testing.

• Hydraulic repair: Main-pump, control-valve, center-swivel-joint and cylinder disassembly and assembly, with PC/LS pressure tests, PPC-valve service and air-bleeding procedures.

• Swing and travel: Swing-motor and swing-machinery overhaul, travel-motor removal and installation, motor leakage tests, and swing-circle bearing-clearance checks.

• Undercarriage and work equipment: Idler, recoil-spring and track-roller service, track-shoe tension adjustment, and removal and installation of boom, arm, bucket and blade assemblies.

• Electronic controls: Potentiometer replacement, electrical-system resetting, automatic-stop checks, controller fault diagnosis and machine-monitor testing, including automatic horizontal excavation equipment.

• Circuit drawings: Actual electrical wiring diagrams, hydraulic piping drawings, CLSS operating diagrams, controller circuit diagrams and connector arrangements support system diagnosis.

Written for service personnel carrying out workshop repairs, this manual is suited to technicians equipped for hydraulic testing, electrical diagnosis and heavy-component handling.

CLSS Hydraulics and Component Repair

The structure-and-function section traces the closed-center load-sensing system through the variable-displacement pump, PC and LS valves, and individual boom, arm, bucket and offset spools. It explains how pump control and pressure compensation interact during combined movements.

Hydraulic-drift tests distinguish internal cylinder leakage from control-valve faults, helping identify which assembly needs attention before teardown. The engine-stalling chart considers servo-valve restrictions, PC-EPC faults and engine-related causes rather than treating every stall as the same failure.

Pump and swing-motor coverage: General specifications identify an HPV105 pump and KMF40AEL-3 (PC128UU-1) or KMF40ABE-3 (PC128US-1) swing motors. The added internal repair sections are labeled HPV95 and KMF40-2 with brake; check the installed component designation before selecting an overhaul procedure.

Pump assembly coverage includes bearing adjustment, shaft rotating-torque checks and mating-surface contact inspection. Swing-motor assembly cautions explain how forcing a misaligned brake case can damage the dowel pin or brake piston.

Engine, Cooling and Undercarriage Service

The S4D102E-1 procedures extend to the water pump, thermostat, turbocharger, starter and alternator, plus removal of the engine/main-pump assembly, radiator and hydraulic oil cooler.

Internal engine work: Detailed engine overhaul requires the separate 102 Series Engine Shop Manual, which is not included in this download. This machine manual provides engine-related testing and component removal and installation procedures.

Fuel-injection-pump installation includes a specific caution about damage to the top-dead-center positioning pin from excessive tightening while it remains engaged.

Power-train and swing-circle descriptions are backed by maintenance standards for idlers, rollers, track shoes and work-equipment joints. Air-conditioning sections address compressor and condenser removal, installation and refrigerant charging.

Workshop reference tables cover metric bolts, flared nuts, split-flange fasteners, lubricant selection by ambient temperature, wire-rope load limits and unit conversions.

Controller Diagnosis and Automatic Excavation

Electrical troubleshooting combines error-code charts, connector-pin tables and machine-monitor checks. Reset procedures address potentiometer replacement, controller replacement and work-equipment changes; mono-boom and long-arm configurations use different signal settings.

The potentiometer section also identifies an arm-linkage installation error that can trigger a fault indication. This gives technicians a documented installation check alongside the electrical tests.

PC128UU-1 machines with automatic horizontal excavation control have separate hydraulic and electrical drawings. The troubleshooting tool list identifies T-adapter box 799-601-7100 and matching adapters for harness and sensor diagnosis.

Follow the manual’s precautions for supported work equipment, hydraulic pressure release and lifting heavy assemblies.

Hydraulic Unloading, Relief and Capacity Preview

The CLSS description specifies pump discharge pressure of 2.45 MPa (25 kg/cm²) with the control valve in neutral and LS pressure at zero.

For the optional two-stage main relief valve, the listed settings are 31.9 MPa (325 kg/cm²) for the first stage and 34.8 MPa (355 kg/cm²) for the second, both at 20 L/min.

The lubricant table gives a specified hydraulic-system oil capacity of 140 liters, including components and piping. This is distinct from the tank’s nominal volume.

PDF Search, Bookmarks and Diagram Detail

Text access and circuit detail: Text search works across much of the manual, but some procedure pages, revision sheets and large schematics lack searchable text. Embedded bookmarks provide access to the main sections and many individual procedures. Small wire codes and connector-pin labels on the large circuit diagrams require magnification.

The download contains one printable 794-page PDF, including the opening publication and contents pages, four revision-list pages and one manual-revision request form. The technical chapters and large-format diagram appendix are contained in the same file.