Arnold & Son is undoubtedly one of the most impressive semi-independent watch manufacturers of the 21st Century. If you don’t believe me, just take a look at the new Constant Force Tourbillon.
The Constant Force Tourbillon
Those of you already in the know will not be surprised that I have chosen the Constant Force Tourbillon to demonstrate my point about Arnold & Son’s growing reputation for excellence. Conversely, those of you who are less familiar with the brand may be tempted to assume that the Constant Force Tourbillon is simply a slightly modified version of the highly popular TB88, the watch that arguably put Arnold & Son first on the map, however nothing could be further from the truth.
That being said, it is true that aesthetically speaking the new Constant Force Tourbillon does share many of the same characteristics of its younger sibling, the TB88. This is not by mistake, of course, as both models belong to Arnold & Son’s much loved Royal Collection and feature similar dial architecture inspired by the creations of the brand’s namesake John Arnold. Both were also created to be as precise as possible, within the confines of their respective limitations of course and hence both have earned the title of chronometer.
With the Constant Force Tourbillon however Arnold & Son have picked up where they left off with the TB88. The most significant development, as you have probably already guessed from the name, is the introduction of a patented constant force mechanism, which drives not only the 60 second tourbillon (also new) but the true-beat seconds hand as well.
To make all that possible, the power from the mainspring charges a small hairspring which in turn releases a consistent amount of power to the escapement/tourbillon once each second. When the power from the mainspring drops below that required by the constant force mechanism, the movement stops rather than run at lower precision.
Now, I’m sure the eagle-eyed among you however would have already spotted that there is not one mainspring barrel but in fact two symmetrical barrels in series, visible dial side at 10:30 and 1:30. The reason for this is because one mainspring barrel would produce significantly different amounts of torque between fully wound and nearly empty, so to maximize power consistency in the Constant Force Tourbillon, the first mainspring barrel is alone responsible for powering the gear train, while the second barrel tops up the first whenever its torque output drops below optimal. This ensures that the power to the regulator flows as constantly as possible.
The end result of all this advance mechanics is that the constant force device rotates once per minute in increments of one second, visually mirroring the rotation of the constantly rotating tourbillon cage, however the two mechanisms perform very different jobs. While the constant force mechanism optimizes precision with the movement in stable positions, the 60-second tourbillon averages out gravitational errors on the escapement by constantly rotating it through 360°. The difference between the rotating tourbillon and rotating constant force device therefore is that the former turns continually while the latter steps in increments of one second. It doesn’t sound like such a big deal but visually it is quite stunning.
The Constant Force Tourbillon is presented in a 46 mm 18-carat red gold case – which as you can see looks sublime on the wrist – and is available as a limited edition of just 28 pieces. Add to that a superb level of finishing and an undeniably eye-catching design and you have a real winner on your hands (well, wrist.)
For more information about the new Constant Force Tourbillon in red gold please visit the Arnold & Son website.