on wheels vs portative

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. 

portative

noun
  • A portative organ. 

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