Komatsu D20, D21A, P, PL Shop Manual

Komatsu D20 and D21 Series Service Documentation

• Covers 1985–2021 Komatsu D20A-5, D20P-5, D20PL-5, D21A-5, D21P-5, and D21PL-5 bulldozer configurations with serial numbers 45001 and up
• Official OEM publication form 00-001, printed May 1981
• Includes 103 detailed component exploded-view diagrams, 4 hydraulic system schematics, and 12 tolerance specification tables
• Downloads to your account within seconds of checkout
• Permanent availability in your purchase account — no re-buy required
• Laid out for standard letter and A4 printing
• Full-text search finds any part number in seconds
• This 1981 shop manual is the primary reference for the 45000-series D20 and D21 build, providing the foundational engine and power-train specifications for the -5 generation models

Component Structure and Maintenance

This Komatsu D20 and D21 service manual provides detailed technical descriptions for the bulldozer chassis, engine, power train, undercarriage, and hydraulic systems. The content is organized by major component group, explaining structure and function to assist in identification and diagnosis. Coverage extends to the operation of the direct transmission versus the Hydroshift transmission, alongside detailed explanations of the main clutch, inertia brake, and steering clutch components. The documentation details the relationship between the steering control valve and steering hydraulic circuits, providing technical context for the tractor's mechanical and hydraulic performance.

Technical Specification Preview

Engine specifications for the 4D94-2N and 4D94-2P are documented in full, detailing 2,940 cc displacement and 39 HP output at 2,450 rpm. Engine lubrication and cooling system parameters are provided, including a standard engine coolant capacity of 13.0 to 13.6 liters. Valve clearance for the intake and exhaust is listed at 0.3 mm in the cylinder head specification table. The torque specification for the sleeve nut on the fuel injection pipe is 7.25 ± 0.25 kg.m. Fuel injection timing is calibrated to 16° before top dead center. Understanding factory workshop documentation is structured for these models is simplified by the inclusion of comprehensive tolerance charts covering standard sizes and repair limits for engine, transmission, and final drive components. A standard 2021 Komatsu D20/D21 Bulldozer shop manual, this publication provides critical technical depth for professional-grade service on the D20–21 series range, including engine, power train, and undercarriage specifications for 45000-series machines.