The oscillating pinion is an effective module used in chronographs. It consists of a movable shaft mounted with two sprockets. The one pinion is in constant engagement with the second wheel of the watch movement, while the opposite after pressing the start pusher after a short swing grips into the chronograph center wheel. By this the connection is established, and the chronograph is running. By pressing another button the oscillating pinion is again moved away from the center wheel, and the Chronograph stops.
For this development, the authority of the Paris 'Bureau for Industrial Property' issued a patent on May 3, 1887. This principle finds application till the present day, for example, in the known and most widely used self-winding chronograph movement Valjoux 7750.