Komatsu D135A-1(S/N 10001-UP)

The Komatsu D135A-1 (S/N 10001-UP) is a mid-size crawler tractor bulldozer, roughly a 30-33 t class machine. It's built around a Komatsu 6D125-1/S6D125-1-family in-line 6-cylinder diesel of 11.04 L displacement with mechanical jerk-pump injection and no electronic engine controls; this serial range is documented as pairing with either the naturally aspirated 6D125-1 or the turbocharged SA6D125-1Q variant tied to it in parts records; confirm aspiration off the engine dataplate. Drive runs through a torque converter and powershift transmission to a two-track undercarriage. Operating weight is reported near 32,800 kg (72,349 lb) in standard trim; treat as approximate until confirmed against the nameplate. Komatsu fitted this platform with straight (S), semi-U (SU), or angle (A) dozing blades, an optional hydraulic tilt cylinder, and a choice of single-shank or multi-shank hydraulic parallelogram rippers, plus a factory-engineered rear towing-winch conversion with its own drawbar and counterweight. This S/N 10001-UP run is the first generation of the line, built into the early 1990s before the D135A-2 (S/N 10301-UP) succeeded it.

The D135A-2 that followed wasn't a simple running update: it stepped up to the larger SA6D140/S6D140-family engine rated near 216 kW (289 hp) gross, while carrying a lighter published operating weight than the D135A-1 it replaced, a reminder that spec figures for this vintage don't always move the direction you'd expect and both numbers should be confirmed rather than trusted at face value. Across the wider family, Komatsu built the D135A-1 alongside its D150A-1 and D155A-1/D155A-2 dozers of the same period, and the group shares enough transmission, hydraulic pump, and undercarriage parts that owners commonly cross-shop sprocket segments and other wear parts across those model lines rather than waiting on a D135A-1-specific order. That parts commonality is what keeps the model relevant today: it's a low-production, largely undocumented machine outside mainstream spec databases, but its simple mechanical fuel system, lack of emissions aftertreatment, and shared driveline family make it a field-rebuildable machine that working owners keep running well past the point a modern electronically-controlled dozer would be retired.

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.