====== Balance spring ======
{{wst>image_r|Spiralfeder|Balance spring}}
[[Spring]]s are used at several places in a watch [[movement]] 

  *for energy storage in the [[winding]] (as [[mainspring]], located in the [[barrel]])
  *at the [[balance wheel]] (balance spring) as part of the [[oscillating system]]
  *as [[shock protection]]

==== Hairspring ====
The spring of the [[balance]] is also called [[hairspring]] (flat spiral). It was invented in [[1675]] (according to another source in [[1665]]) by [[Huygens, Christiaan|Christiaan Huygens]]. Here the points of attachment of [[balance staff]] and [[balance cock]] (stud) lie on the same plane.

Although flat spirals have worse results than [[Breguet hairspring]]s (see below), because they - unlike those - don't move exactly concentric during expansion and contraction, they are the most common type of spiral in mechanical watches.

==== Breguet spiral ====
[[Abraham-Louis Breguet]] invented this type of balance spring (also called [[Breguet hairspring]]), which has a bent terminal curve. Especially [[Rolex]], unlike many other luxury watch manufacturers, is using this type of hairspring in its models. See also the new Rolex development of the [[Parachrom blue]] spring.

==== Auto-compensating spiral ====
Balance springs made of spring steel have the disadvantage that they are changing their elasticity with temperature fluctuations. This also changes the speed of the clock. In the [[1930]] years, after intensive research, a new balance spring has been developed consisting of an alloy of different metals, which was able to compensate temperature changes. In [[1933]] these springs entered the watch market under the name "[[Nivarox]]". Because of its advantage over normal spring steel, they attained a rapid spread. Today Nivarox is also the name of the most famous manufacturer of flat spirals.

==== Silicon hairspring ====
In this newer development, the spiral is made of polycrystalline silicon. Compared to conventional spirals, this type has the following advantages: 

  * Improved isochronism (regularity of oscillation).
  * [[Anti-magnetic]]
  * Temperature compensation due to the material properties.
  * No thermal or mechanical degradation at the attachment points, unlike conventional spirals
  * Insensitivity to small impacts and thus reduced rate deviations
  * Reduced sensitivity to centrifugal and gravitational forces, as three times lighter than conventional spirals

===== See also =====
  * [[Nivarox]]
  * [[SPRON]]


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