Rattrapante watches, also known as split-seconds chronographs, are timepieces that have two seconds hands that can be started, stopped, and reset independently of each other. This complication is often used in timing events where there are two separate time intervals that need to be measured simultaneously, such as a race with multiple laps.
The rattrapante mechanism works by having an additional button or pusher on the watch that controls a second hand, which can be stopped and started independently of the primary chronograph hand. When the pusher is activated, the two hands will move together until the secondary hand is stopped using the same pusher. The primary hand will continue to move while the secondary hand is stopped, allowing the wearer to measure a separate time interval. When the pusher is activated again, the secondary hand will catch up to the primary hand and continue to move in unison.
These watches are highly sought after by collectors due to their complexity and rarity. They require precise engineering and are often hand-assembled, which can make them quite expensive. However, they are a testament to the craftsmanship and ingenuity of watchmaking.
