- trolley framed
 
-   A locomotive that uses bogie trucks (like all of the diesel power produced
  by all of the north american locomotive builders)
 
- locomotive framed
 
-   A locomotive that uses coupled trucks (like a Mallet steam locomotive.)
  The Parsons Vale mechanical department has a strong preference for this
  sort of power, because it allows for lighter superstructures and (arguably)
  better tracking at speed.