Komatsu GD705A-3(S/N 10002-UP)

The Komatsu GD705A-3 (S/N 10002-UP) is a large articulated motor grader in Komatsu's 700-series line, built around a front-steer axle and a tandem-driven rear bogie carrying the frame's weight over dual wheel sets on each side. The lineup around this chassis runs on a Komatsu 6D125-family diesel, with the wider A-series line documented in naturally aspirated (6D125-1) and turbocharged (S6D125-1) form depending on production year; the exact rating fitted to this specific S/N 10002-up block is not confirmed in factory literature, so the engine data plate is the final word. Drive goes through Komatsu's own Hydroshift power-shift transmission, a fully mechanical-hydraulic unit with no electronic transmission control. Operating weight for this size class runs roughly in the 17,500 to 19,300 kg range depending on configuration and series, with a moldboard in the neighborhood of 4.3 m (14 ft) wide typical of the family. The GD705A-3 sits between the earlier GD705R-2 and the later GD705A-4 (S/N 21001-UP), which picks up numbering where this serial block ends; factory configurations typically included a front dozer blade, ripper/scarifier attachment, and moldboard width options ordered to job requirements.

The move from the R-series to the A-series replaced the GD705R-2's Cummins-derived mechanical engine and TORQFLOW torque-converter transmission with Komatsu's own engine family and the Hydroshift power-shift driveline, giving smoother, more consistent shifting and centralizing engine and transmission sourcing under one Komatsu part system. The GD705A-3 still predates electronic engine and transmission controls: it runs an analog gauge cluster with warning lamps for charge, engine oil pressure, coolant temperature, air cleaner restriction, transmission oil temperature, parking brake, and brake oil pressure, with no CID/FMI fault codes to pull. That makes it mechanically straightforward to diagnose and keep running compared with later electronically controlled graders. In the used and parts market today, these machines are valued as simple, rebuildable haul-road and site-grading platforms without an ECM to fail, but documentation is thin: most published spec sheets and catalogs only cover the later GD705A-4/GD705-5 or the earlier GD705R-2, so correct parts identification depends on reading the serial number and data plate rather than assuming shared specs across the family.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.