power car vs switcher

power car

noun
  • A vehicle equipped with machinery for supplying heat or electrical power to other parts of a train. 

  • A vehicle that propels, and commonly also controls, a passenger train or tram, often as the lead vehicle. 

  • Antonym: trailer car 

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 power car and switcher occurred in a corpus of books? (source: Google Ngram Viewer )