CLC S6 Slug 701BKelso WA Kelso

What is a slug?

@Joaozito It's additional set of bogies with traction motors, without its own diesel engine, so the electricity is transmitted from coupled "fullsize" loco via cable.

@EightyFour Thanks. French SNCF had slugs too, converted from old BB 63000 (Brissonneau&Lotz).

Also known as TEBU (Tractive Effort Booster Unit), Electric Trailer and Drone. These units help utilize low-speed horsepower that the main unit produces. Switching slugs like this are usually set to cut out when the speed exceeds 30 mph, since they are effective only at lower speeds anyway. Thanks for the comments, guys!