22/08/2026
Presentinf The Audemars Piguet Royal Oak Double Balance Wheel Openworked Reference 15407
Audemars Piguet has been killing chronometrie for many generations. This watch, the reference 15407 Royal Oak Double Balance Wheel Openwork, is one of several innovative techniques put forth by AP to do nothing but tell time better and more accurately – and they’ve done it in a beautiful openworked Royal Oak. How? Well, the name of the watch might give you a hint – this RO has two balance wheels.
The openworked Royal Oak has been around for years, but the originator of this line could be 2010’s 15305. Then, we saw in 2012 and 2014 respectively, the traditional 39 mm Jumbo get “openworked” in platinum and rose gold. In 2016, we saw the 41 mm Royal Oak, reference 15400 openworked for the first time, but with a double-balance wheel escapement that was a world’s first!
Now AP has produced a few very high-end watches in the past that used two balance springs, but not two balance wheels. They include the Millenary Quadriennium and Millenary Minute Repeater with AP Escapement. The thinking here is that having two balance wheels creates an oscillator with more mass, ensuring great stability – why, for example, you see huge oscillators in marine chronometers. In previous watches, the two balance springs would counteract the effects of gravity on the balance itself. Basically whenever the balance spring contracts, it tends to push the sides of the balance staff against the sides of the cap jewels.
That extra friction affects rate, and it does so to a different amount depending on the position of the watch. Theoretically, the double balance springs should cancel out each other’s rate errors in the vertical position as well.
Content courtesy of the great Lucy Timepieces Official
