Invented and patented by Tag Heuer in 1887 an oscillating pinion is a part of a chronograph or stopwatch. It is comparable in principle to a car’s transmission system. It is constructed from a moving rod and two pinions, and an oscillating pinion is in place of the two large wheels usually found in chronographs.
A chronograph is able to function more accurately thanks to this mechanism due to a coupling system which attaches the chronograph section to the watch section of the movement with optimal precision.
Watchmakers still commonly use oscillating pinions today in the manufacture of mechanical chronographs for example the Tag Heuer Calibre 1887.
Onion WatchOscillating Weight or Rotor