Manually-wound watches For many mechanical watch owners it is a pleasant ritual, a recurring moment: the hand-wound movement, which needs to be wound regularly using the crown. Doing this directs new energy to the mainspring barrel so that the timepiece keeps ticking.

The power reserve varies by model. In some cases, the watch may need to be wound every 36 hours, while other watches – such as the LANGE 31 – only every 31 days. To make such an enormous power reserve a reality, the model possesses a twin mainspring barrel housing two mainsprings with a length of 1,850 mm. The special winding key ensures a better gear ratio than when winding the crown by hand. Consequently only a few rotations of the hand are needed for the watch to be fully wound.

Technical drawing of the LANGE 31 winding key