Power reserve
The power reserve indicator shows the remaining time until the stoppage of a mechanical clock and thus gives information about whether or when the clock has to be wound again. As a power reserve or transition duration is defined as the time that runs a clock for a rearing until they must be brought up again.
Origin
This form of display was originally developed for marine chronometers (including set-up and Abwerk called ). The aim was to ensure the accuracy of the range needed to determine the longitude clock through a targeted pulling at each of the same remaining power reserve, since in particular can lead almost completely strained or relaxed spring to inaccuracies.
The technical feasibility of different methods were used. Abraham Louis Breguet sat down in 1800 by his construction of a differential screw.
In watches a power reserve indicator was first implemented in 1933 in a clock of Breguet. Due to the technical complexity have been and power reserve displays found in wristwatches only in the higher price range.
For watches with automatic winding Power reserve ads were initially installed to signal the carrier that the automatic worked and had generated sufficient potential energy. The efficiency with automatic watches with pendulum flywheel and side -winding rotors fell due to a not yet exploited 360 ° in both directions lower. Through the power reserve indicator stalling the clock by additional manual winding could be avoided. Nowadays, power reserve indicators are also often used for aesthetic reasons.