on wheels vs unattached

on wheels

prep
  • Used other than figuratively or idiomatically: see on, wheels. (Having wheels affixed to the bottom, and so transportable; synonym of wheeled). 

  • Mobile; able to be moved; especially, synonym of on the move. 

  • To a large degree, excessively. 

unattached

adj
  • Not connected with or belonging to a particular group or organization. 

  • Not attached or joined; disconnected. 

  • Not married and not involved in a romantic relationship. 

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