crossbeam vs hammer beam

crossbeam

noun
  • A horizontal structural beam that runs perpendicular to the primary support beams; a girder. 

  • A beam laid across the bitts, to which the cable is fastened when riding at anchor. 

hammer beam

noun
  • A member of a kind of roof truss (a hammer-beam truss), so framed as not to have a tiebeam at the top of the wall. Each principal has two hammer beams, which occupy the situation, and to some extent serve the purpose, of a tiebeam. 

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