axletree vs trunnion

axletree

noun
  • A spindle or axle of a wheel. 

  • A stimulus or driving force. 

  • A bar or beam of wood or iron, connecting the opposite wheels of a carriage, on the ends of which the wheels revolve. 

trunnion

noun
  • A similar rotational bearing comprising a rotating arc or ring sliding in the groove of a stationary arc, used in machinery to allow a workpiece to be moved relative to a fixed tool. 

  • A similar rotational bearing used in automotive suspensions. 

  • A shaft, held by a bearing, at each end or side of a rotatable object. 

  • One of the short stubby bearings on either side of a cannon; a gudgeon. 

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