A diesel-electric unit that burns dirty, slips rings, or suffers from turbo lag, causing it to belch thick black or white smoke under load. The nickname originally targeted older Alco units famous for their heavy exhaust plumes, but it applies to any poorly running diesel that obscures the right-of-way like a coal-burner.
Heard on the job
That old Geep is pulling so hard it turned into an honorary steam locomotive on the grade.
Insider tip
When a diesel smokes this much, mechanics know it is wasting fuel and likely needs ring or injector work.