axle vs two-byfour

axle

noun
  • The pin or spindle on which a wheel revolves, or which revolves with a wheel. 

  • A transverse bar or shaft connecting the opposite wheels of a car or carriage; an axletree. 

two-byfour

How often have the words axle and two-byfour occurred in a corpus of books? (source: Google Ngram Viewer )