Watch Springs: The Power Behind Self-Winding Watches

Self-winding watches are amazing. No need to replace batteries. No hassle in having to wind them. As the name says it all, self-winding watches wind themselves up. All one has to do is wear them.

The secret behind a self-winding watch’s power lies within the operation of a simple principle: wind-up watch springs.

Watch springs are commonly called a watch’s mainspring, while certain watch brands refer to them as a watch’s motor spring. Either way, their function remains the same; watch springs/mainsprings/motor springs store wound up energy important for wind up watches to successfully operate.

Watch springs are strips of hardened steel or steel alloy. They often come 0.05-.02 millimeters thick and 200-300 millimeters long. These days, watch springs are stainless and have strong elastic tolerances. 1945 saw carbon-steel alloys making up watch springs. Later followed by “newer” alloys (like iron-nickel-chrome and cobalt-molybdenum-beryllium), structurally hardened metals have become a standard for watch springs.

The metal is coiled inside a barrel-like containing unit. The “winding” is estimated to enable the watch to function for 36 to 40 hours. There’s a power reserve that lasts for 12 to 16 hours, the normal standard for self-winding watches. Taken out of a watch’s barrel-like containing unit, watch springs come in three distinct shapes:

Semi-reverse shaped watch springs – the outer end of a spring is coiled in reverse direction to form a less than 360 degree angle.

Reverse (resilient) shaped watch springs – the outer end of the watch spring is coiled in reverse direction to form an angle more than 360 degrees.

Spiral coiled – the direction of the watch springs’ coil is the same from end to end.

A self-winding watch works with the wind-up principle that made/makes a wind-up watch. The only difference therein is that self-winding watches have an add-on gear system that enables them to self-wind.

An oscillating gear is positioned in the middle of the device. The gear moves congruent to the wearer’s movement. The revolutions produced by the gear, as the wearer moves about, is utilized to wind up the watch’s springs, thus making the watch self-winding.

The first of its kind came out in 1770 when Abraham-Louis Perrelet invented a self-winding system for fob watches. This was further improved by Abraham-Louis Breguet who eventually developed his own design of self-winding watches.

Both utilized what is now known as watch springs. By 1923, John Harwood made the most fully self-winding of self-winding watches, which led to the self-winding watches we know today.

Great things do come from small beginnings, as small things, like watch springs, power great things.