Editing Torsion spring (section)

==Torsion, bending==
Torsion bars and torsion fibers do work by torsion. However, the terminology can be confusing because in helical torsion spring (including clock spring), the forces acting on the wire are actually [[bending]] stresses, not [[Deformation (mechanics)|torsional]] (shear) stresses. A helical torsion spring actually works by torsion when it is bent (not twisted).<ref>{{Citation
|last=Shigley
|first=Joseph E.
 |author2=Mischke, Charles R. |author3=Budynas, Richard G.
|title=Mechanical Engineering Design
|publisher=McGraw Hill
|location=New York
|year=2003
|page=542|url=https://books.google.com/books?id=j8xscqTxWUgC&pg=PA542
|isbn=0-07-292193-5}}</ref><ref>{{Citation
  | last = Bandari
  | first = V. B.
  | title = Design of Machine Elements
  | publisher = Tata McGraw-Hill
  | year = 2007
  | page = 429
  | url = https://books.google.com/books?id=f5Eit2FZe_cC&pg=PA429
  | isbn = 978-0-07-061141-2}}</ref>
We will use the word "torsion" in the following for a torsion spring according to the definition given above, whether the material it is made of actually works by torsion or by bending.