freewheel vs struggle

freewheel

noun
  • a device in a transmission that disengages the driveshaft from the driven shaft when the driven shaft rotates faster than the driveshaft. 

verb
  • To operate free from constraints. 

  • To operate a motor vehicle which is coasting without power, e.g. downhill. 

  • To ride a bicycle without pedalling, e.g. downhill. 

  • To continue spinning after disengagement. 

struggle

noun
  • A contortion of the body in an attempt to escape or to perform a difficult task. 

  • Strife, contention, great effort. 

verb
  • To strive, to labour in difficulty, to fight (for or against), to contend. 

  • To strive, or to make efforts, with a twisting, or with contortions of the body. 

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