Every wristwatch needs a source of power in order to operate, either using a battery, winding the movement or using some other means. For mechanical watches, the movement is powered by its mainspring, which is either wound by hand or automatically, via an internal rotor. Keeping a modern mechanical watch wound is a fairly simple process, however knowing exactly how much power reserve a watch has is difficult to determine, unless it is equipped with a specialized indicator. In this article, we will provide an overview of the power reserve complication in watches as well as a closer look at one of Seiko’s premium automatic movements that features a very unique indicator, the SII NE57.
To better understand the concept of power reserve, it is important to first understand where the power is generated in a watch. Mechanical movements are powered by a coiled spring known as a mainspring, which is the mechanical fuel tank of the watch’s “engine.” When you wind up a watch, this spring accumulates power as tension builds in the spring, that energy is eventually released back into the watch and keeps the watch running. This accumulated energy or power in the mainspring is the “power reserve” of the watch. As the spring uncoils, the remaining amount of time that the watch can run diminishes. If a mechanical watch is left untouched or wound, this reserve will eventually run down and it will stop running when it runs out of “fuel.”
Watchmakers have developed watches with power reserve displays to eliminate the guesswork of how long your watch will run without needing to be wound. These power reserve displays work much like the fuel gauge in a car and show a range from "full" to "empty." The indicators are often shown in four different ways, with a:
- linear device
- 3D structure
The most common and typical power reserve indicator seen is designed much like a stereotypical gauge, with a lever or hand pointing to the remaining power reserve. However, some movement makers have created calibers that offer a more unique approach to this often mundane complication. For those who are looking for something more unusual or creative means for displaying power reserve, the Seiko Instruments Caliber NE57 provides a unique alternative. The NE57 is part of Seiko’s ‘Premium Line’ of mechanical movements, with 29-jewels, 41 hour power reserve and a centrally located power reserve indicator, which can provide many different display options.
The versatility of the NE57's central power reserve complication provides opportunities for brands to incorporate power reserve indicators into their designs from relatively conservative gauges to more modern and creative displays. Throughout the article, we have featured several models from makers such as Aragon
, and Seiko
, who all provide their own unique spin on utilizing the central power reserve. As you can see from the photos, the designs can be quite striking, such as the aviation inspired display of the Harbinger Marauder
, which is one of our favorites.
Now that we’ve provided you a brief summary of the basics surrounding power reserve and power reserve indicators, we encourage you to go out into the market and find additional examples. The models highlighted in this article are just a few of those available in market, so get out there and explore the myriad of others. Happy hunting!
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