The Mitsubishi HG-SR51K is a servo motor from the HG series, sitting in the Motors & Motor Controls category. This is the part number you'd write on a BOM line for a motion-control axis — a servo motor that pairs with a Mitsubishi servo drive to position a load on a conveyor, rotary table, or pick-and-place gantry.
No cross-reference or substitute is needed — this is the part the BOM calls for.
What this part is for
A servo motor like this one is the muscle behind closed-loop motion control. It turns electrical commands from a servo drive into precise shaft rotation — position, speed, or torque — for the axes on a machine tool, packaging line, or assembly cell. The HG series is Mitsubishi's general-purpose servo line, used across factory automation where you need repeatable positioning and a compact motor footprint.