air cushion vs shock absorber

air cushion

noun
  • A shock absorber that uses an air chamber. 

  • A layer of trapped air that supports a hovercraft. 

  • A rubber or plastic inflatable cushion. 

shock absorber

noun
  • A mechanical device designed to smooth out or damp any sudden shock impulse and dissipate kinetic energy; usually consists of a combination of a spring and a dashpot. 

How often have the words air cushion and shock absorber occurred in a corpus of books? (source: Google Ngram Viewer )