A chronograph in which a single button controls start, stop and reset in sequence.
A mono-pusher chronograph is a chronograph complication controlled by a single button rather than the two pushers found on most modern chronographs. Press it once to start timing, again to stop, and a third time to reset, with each press cycling through the sequence in order.
The format predates the two-pusher chronograph. Early chronographs, including pocket watches, used a single pusher integrated into the crown, since the mechanism to separate start, stop and reset into independent pushers hadn't yet been developed. The two-pusher layout became the norm through the twentieth century because it lets a wearer stop and reset without needing to time the sequence of presses, but the mono-pusher format never disappeared and is now mostly found in high-end and independent watchmaking, where it's often chosen for its historical character and the cleaner case architecture a single pusher allows.
Because the same button drives three functions, the movement inside a mono-pusher chronograph tends to be mechanically more complex than a standard two-pusher column-wheel chronograph, which is part of why the complication is often reserved for higher-end pieces.
It's a chronograph where a single pusher, rather than two, controls start, stop and reset in sequence. Press once to start timing, again to stop, and a third time to reset.
Chronographs originally used a single pusher because the mechanism didn't yet exist to separate the functions. The two-pusher layout came later and became the standard, but the mono-pusher format persisted, particularly in high-end and independent watchmaking.
Not necessarily. It requires timing your presses correctly since the same button drives three functions in sequence, and the movement behind it is often mechanically more complex than a standard two-pusher chronograph.