How does a pusher work?
Pressing a pusher sends force down a stem into the movement. At the far end sits a lever or cam. The push moves that part, and it triggers a mechanical action. On a standard chronograph, the button at two o’clock usually starts and stops the timing. A second button, usually at four o’clock, resets it. Pressing reset sends the chronograph hand back to zero. Some pushers screw down. Once locked, they cannot be pressed by accident.
What else are pushers used for?
Pushers are not only for chronographs. Small recessed pushers on the side of the case can correct the date, the month or the moon phase. A monopusher chronograph uses a single button for the whole timing sequence. Each press moves it to the next step: start, then stop, then reset, always in that fixed order.
Where it comes from
On early chronographs, the crown did two jobs. It wound the watch, and it also worked as the chronograph pusher. In 1934 Willy Breitling added a second pusher, placed at four o’clock. That led to the two-pusher layout. On a standard chronograph, one button, usually at two o’clock, starts and stops the timing. The other, usually at four o’clock, resets it.
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