Magnetically actuated model railroad coupler

A coupler assembly for a model railroad car, the assembly comprising:

• a first shank comprising a distal portion with a coupler knuckle and a proximal portion including a flat portion having a circular outer surface and a concentric circular opening;
• a second shank comprising a distal portion with a coupler thumb and a proximal portion including a flat portion having a circular outer surface with a radius substantially the same as the radius of said circular outer surface of said first shank flat portion and a concentric circular opening the center of which substantially coincides with the center of said circular opening in said first shank;
• a coil spring with a circular planform having a first turn and a second turn terminating in respective first and second end portions, said first turn including a first interlocking offset that passes through an opening in said first shank and said second turn including a second interlocking offset that passes through an opening in said second shank, and said flat portions of said first and second shanks including spring grooves accepting said coil spring to permit said flat portions to lie in face-to-face contact, wherein said coil spring has a radius slightly larger than the radius of said circular outer surfaces of said first and second shanks so that said first and second turns of said coil spring are disposed outside the periphery of said circular outer surfaces;
• and
• a mounting box for mounting to the railroad car and having a circular mounting post with an upright axis generally perpendicular to the direction of travel of the model railroad car along a track and generally perpendicular to a plane of the track when the model railroad car is in place thereon, said mounting post accepting said circular openings in said first and second shanks for permitting rotation of said shanks relative to each other about the upright axis between a closed position in which said knuckle and thumb cooperate with a coupler on another model railroad car to couple the railroad cars together and an open position in which said knuckle and thumb permit the railroad cars to separate, wherein said first and second end portions of said coil spring engage said mounting box to bias said shanks into their closed position and into a position in which said shanks are generally aligned with the direction of travel of the model railroad car along the track.