sprocket vs sprocket wheel

sprocket

noun
  • A toothed wheel that enmeshes with a chain or other perforated band. 

  • The tooth of such a wheel. 

  • A placeholder name for an unnamed, unspecified, or hypothetical manufactured good or product. 

  • A flared extension at the base of a sloped roof. 

sprocket wheel

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