====== Power reserve indicator ======
{{wst>image_cl|Blancpain|L-evolution Réveil GMT Gold|[[Blancpain L-evolution Réveil GMT]] with [[power reserve indicator]] for the [[movement]] as well as for the [[alarm function]]}}

A **power reserve indicator** indicates the state of winding of the [[mainspring]] [[barrel]].

===== Overview =====
Power reserve indicators (known as "Réserve de Marche" in French) were developed alongside [[long power reserve]] movements which can run for more than 2 days. Typically shown on the [[dial]] with a [[pointer]], power reserve indicators are also sometimes located on the movement itself, visible through a [[display caseback]] or aperture. They are often geared directly to the [[winding system]] and usually use a gearing mechanism based on estimated power for a given number of winding turns. Others are attached to the [[barrel]] and use mainspring torque as an indicator of power reserve remaining.

Some power reserve indicators are marked with a fixed number of days, while others show a simple "+/-" or "ab/auf" ("up/down" in German). There can also be power reserve indicators for further functions, for example the [[alarm function]].

===== History =====
[[Breguet]] developed a prototype power reserve indicator in [[1933]] but did not bring it to production. [[Jaeger-LeCoultre]] introduced the modern power reserve indicator in [[1948]] on the [[Jaeger-LeCoultre Powerwind|Powerwind Ref. 163]] watch's [[JLC 481|Cal. 481]]. Jaeger-LeCoultre heavily marketed this feature in the [[Jaeger-LeCoultre Futurematic|Futurematic]] watches of the 1950s and continues to offer a model bearing the name, [[Jaeger-LeCoultre Réserve de Marche|Réserve de Marche]] today. [[Zodiac]] was another early company to use a power reserve indicator, introducing it in [[1949]] on a pioneering [[automatic]] watch movement.

===== See Also =====
  * [[Power reserve]]
  * [[Long power reserve]]


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