The Komatsu PC55MR-3 midi excavator has a Komatsu 4D88E-6 direct injection engine producing 38.2 flywheel horsepower (FWHP). It has an operating weight of 11,375.9 pounds (5,160 kg). It comes standard with hydrostatic drive, automatic two-speed travel, standard auxiliary hydraulics, spacious operator station with a two-post ROPS canopy or cab, tilt-forward operator station for full engine access, large diameter swing pin, O-ring face seal hydraulic fittings, and a high strength X-track frame. It is available with rubber, steel, or roadliner crawler tracks. It also features KOMTRAX technology, which sends location, service meter readings, and operation maps to a secure website.

The PC55MR-3 has a HydrauMind hydraulic system that delivers fluid at a rate of 37.2 gallons (140.8 L) per minute at a system pressure of 3,840 pounds per square inch (26,475.8 kPa).

The PC55MR-3 has a track gauge of 61.2 inches (156 cm) with 15.7-in (40-cm) shoes.