STOPWORK

The stopwork is the device that limits theWinding of the Mainspring by mechanically blocking the rotation of the Barrel arbor when the spring reaches its maximum admissible tension. Without a stopwork, excessive winding exposes the spring to breakage. The classic mechanism, inherited from early horology, combines a wheel fixed to the barrel arbor, bearing a stop finger, with a Maltese cross mounted on an intermediate pinion: at each complete turn of the arbor, the finger advances the cross by one step, until one of its solid branches comes to rest against the finger and prevents any further winding. This device, also called an end-of-run stop, coexists with the Click anti-return and the Crown winding. In many modern calibers, it has given way to a simple torque limiter or a slipping spring (bridle), or even disappeared entirely, the Barrel then being sized to tolerate full winding without damage.