throw a spanner in the works vs throw a wrench in the gears

throw a spanner in the works

verb

  • To introduce a problem, dilemma or obstacle, something unexpected or troublesome. 

throw a wrench in the gears

verb

  • Synonym of throw a spanner in the works. 

How often have the words throw a spanner in the works and throw a wrench in the gears occurred in a corpus of books? (source: Google Ngram Viewer )