steam locomotive vs switcher

steam locomotive

noun
  • A locomotive, usually for use on a railway, that is powered by steam. 

switcher

noun
  • A railway locomotive used for shunting; a shunter. 

  • A switchmode power supply. 

  • Synonym of vision mixer (“device for selecting between video sources”) 

  • One who or that which operates a switch. 

  • One who or that which switches, or changes to something else. 

How often have the words steam locomotive and switcher occurred in a corpus of books? (source: Google Ngram Viewer )