North American precision regulation, one century ago.
The Elgin National Watch Company, better known as Elgin Watch Company, was one of the largest US watch manufactures in history between 1864 and 1968.
Elgin Serial Number : 10626035
Production Year :1904
Jewels :17 jewels
Run Quantity :1000
Production Dates :1899 to 1906
Total Grade Production :62900
Movement Configuration :Hunter Case Bridge Layout
Movement Setting :Pendant Wind and Set
Movement Finish :Nickel Damaskeening
Plate :3/4 Plate
Barrel :Going Barrel
The “SAFETY PINION” name engraved below the balance cock referred to a system protecting the barrel teeth in case the mainspring broke. Early mainsprings were made of carbon steel and would inevitably fatigue and fracture. When they broke the mainspring would instantly unwind and cause a severe jarring on the barrel that could, in essence cause barrel teeth meshing with the centre wheel pinion to be broken.
The safety pinion was a system where by the centre pinion was screwed onto the centre wheel instead of being riveted. This allowed the wheel to unscrew when the mainspring broke. In normal use the centre wheel would be constantly in the locked position turning the centre wheel pinion and driving the gear chain.
For precision, and easy adjustment of the index regulating the rate of the balance spring, the end of the index sat in the centre of a special nut that was screwed on to a curved thread. As the watchmaker would turn the nut the index would then moved.
Thanks to the The K&H Watchmaking Competence Centre for the loan of this watch
and to Roland G Murphy for the archive details.