Komatsu D80A-12 / D85A-12 Bulldozer Repair Manual (P/N 06–76 (03) 03001)

This 378-page PDF is the Komatsu shop manual for D80A-12 and D85A-12 bulldozers, serial 10001 and up, including angledozer and tilt-dozer equipment and the Cummins NH-220-CI engine installation. Written for shop personnel, its repair depth, heavy-component lifting, press work, dial-gauge checks, and part-numbered service tools make it suited to experienced heavy-equipment technicians with a properly equipped shop, not entry-level maintenance. The title page carries code 06-76 (03) 03001.

• D80A-12 driveline: Covers the wet multi-disc over-center main clutch, hydraulic clutch booster and oil pump, inertia brake, constant-mesh transmission, shift interlock, gearshift lever and fork service, and the transmission lubrication system.
• D85A-12 driveline: Details torque-converter removal and overhaul, scavenge-pump and pressure-relief-valve service, planetary Torqflow transmission teardown and assembly, clutch inspection, and control-valve work. Separate torque-converter chapters cover S/N 10001-11839 and S/N 11840-up.
• Optional F3-R3 Torqflow supplement: Adds drive-flow explanations, transmission disassembly and assembly, inspection criteria, control-valve inspection, a hydraulic circuit diagram, and transmission pressure measurement and adjustment.
• Steering and final drive: Includes bevel gear and shaft removal, tooth-contact adjustment, steering clutch and brake repair, steering control-valve and oil-pump service, plus final-drive disassembly and inspection.
• Undercarriage and dozer equipment: Covers tracks, track frames, front idlers, carrier and track rollers, recoil spring, equalizer bar, blade, push arms, lift and tilt cylinders, and cylinder stays. The tilt-blade breakdown identifies the S/N 15478-up arrangement.
• Hydraulics and factory standards: Provides control-valve, PAL-160 pump, oil-filter, and cylinder procedures, backed by assembly clearances, wear and service limits, torque specifications, spring criteria, pressure settings, and fluid-capacity data.

Configuration-Specific Implement Hydraulics

The implement-hydraulic section separates four control arrangements: the angledozer valve, the angledozer-and-ripper valve, the triple-spool valve for a tilt dozer with ripper, and the twin-spool tilt-dozer valve. It explains the check, suction, safety, and control valves and follows the related oil paths through the tank, pump, filter, blade-lift cylinders, tilt cylinder, and ripper circuit where fitted. Removal, disassembly, inspection, reassembly, and seal-related checks are included for the serviceable assemblies.

Useful illustrations include the D80A-12 and D85A-12 powertrain layouts, the constant-mesh transmission lubrication diagram, torque-converter oil-pump and circuit views, Torqflow control-valve and hydraulic schematics, steering-control-valve flow diagrams, and the machine electrical wiring diagram. Exploded assembly views identify the parts and installed relationships within the clutch, transmission, converter, steering, final drive, undercarriage, blade, and hydraulic cylinders.

Shop Procedures, Tools, and Repair Cautions

Major procedures cover radiator and engine removal, PTO disassembly and inspection, engine installation and centering, transmission and torque-converter teardown, bevel-gear contact adjustment, track opening, recoil-spring service, and hydraulic-cylinder rebuilding. The manual names service tools where ordinary pullers or shop methods could damage parts, including 09780-00000 for the bevel-gear hub, 09713-00000 and 09703-00000 for final-drive work, 09731-00000 for opening the tracks, and 09730-00000 for recoil-spring compression.

The optional F3-R3 section flags incorrect ring-gear orientation and piston-ring damage, followed by a piston operation test before the case is closed. The D80 clutch-booster section warns that blocked pump flow can rapidly damage the booster or pump and explains the relief valve that protects the circuit.

Track tension, recoil-spring work, and engine or transmission removal involve stored pressure and suspended heavy assemblies. Pressure must be relieved and the specified press, lifting gear, and supports used before repair work begins.

Engine and Electrical Scope Limits

The engine chapter covers radiator removal, engine and PTO removal, PTO service, installation, and engine-to-transmission centering; it does not provide an internal Cummins engine overhaul. Electrical coverage consists of the machine wiring diagram and basic system description. The manual directs full electrical-component operation and maintenance to the separate publication Electrical Equipment for KOMATSU-CUMMINS Diesel Engines.