car vs railroad truck

car

noun
  • A wheeled vehicle that moves independently, with at least three wheels, powered mechanically, steered by a driver and mostly for personal transportation. 

  • A clique or gang. 

  • The part of an airship, such as a balloon or dirigible, which houses the passengers and control apparatus. 

  • The aggregate of desirable characteristics of a car. 

  • A floating perforated box for living fish. 

  • The first part of a cons in Lisp. The first element of a list. 

  • an individual vehicle, powered or unpowered, in a multiple unit. 

  • An unpowered unit in a railroad train. 

  • A passenger-carrying unit in a subway or elevated train, whether powered or not. 

  • A rough unit of quantity approximating the amount which would fill a railroad car. 

  • A sliding fitting that runs along a track. 

  • The passenger-carrying portion of certain amusement park rides, such as Ferris wheels. 

  • The moving, load-carrying component of an elevator or other cable-drawn transport mechanism. 

railroad truck

noun
  • A chassis or framework-like structure underneath a railroad car to which wheel axles (and, hence, wheels) are attached through bearings. (Not to be confused with railway truck or railtruck, which are British English synonyms of railroad car) 

How often have the words car and railroad truck occurred in a corpus of books? (source: Google Ngram Viewer )