Spiral timepiece balance spring - with adjustment of active spring length via setting pin

摘要

The spiral timepiece balance spring (6) has the inner side of the outermost active winding (4) of the spring (6) acted on by a setting pin (1), so as to define the active length of the balance spring (6). The setting pin (1) and its mounting (12), at least in the vicinity of the three bearing surfaces for the inner and outer sides of the outermost spring winding (4) and for the bottom of the latter respectively, lies above the level of the latter respectively, lies above the level of the third bearing surface for the bottom of the outermost spring winding (4). Pref. the setting pin (1) is made from steel and fits into a corresponding aperture in the holder (12).