Complications
Dennis.raul initiates a fascinating technical discussion comparing the Straumann double hairspring with the tourbillon, two distinct approaches to enhancing watch accuracy. His post delves into the theoretical advantages of the double hairspring in negating gravitational effects across various positions, a critical aspect for precision timekeeping. This exploration offers valuable insights into the intricate mechanics that drive high-horology movements.
Straumann double hairspring
In any watch movement, the balance wheel and its hairspring are subject to gravitational forces that influence their rate and therefore the accuracy of the watch. That is especially true with a flat hairspring, like a Straumann.
Several ways of compensating these effects have been followed during the history of watchmaking.
One was to act on the hairspring directly, either on its shape (cylindrical or spherical hairsprings) or on its attachment to the balance and to the stud, with terminal curves (best known, the Breguet overcoil).
A second way, also compensating for the effect of gravitation on the balance itself, was to mount the entire escapement device (balance wheel, hairspring, pallets, escape wheel) on a rotating carriage which is known as “tourbillon” or “carrousel”.
The double hairspring. Two hairsprings on top of each other and their spirals are opposed (one turning clockwise the other anti-clockwise). So when the hairsprings are beating, they expand and contract in the opposite direction to each other. When the gravity center of the lower hairspring moves to the right, the gravity center of the upper one moves the same amount to the left, compensating each other and keeping the gravity center in the center of the balance wheel. Thus guaranteeing that timing accuracy is the same in every position on the wearers wrist.
See the graphic underneath to view the movement of the gravity center of different hairsprings.
Excellent question. Here's my extremely imperfect understanding. All corrections more than welcome (Jonh, Suitbert, you know who you are ). The "center of gravity" displaces in a normal balance even when the balance is horizontal, and I'm assuming this is what your graph shows. This is due to the attachment points adding a variable force into the spring as it oscillates. It creates a problem as the balance staff is forced against the pivot in a variable way, whcih introduces errors. The double b
Interesting points. The Bayer guys say this about the gravitational 'sag' Apparently since the two hairsprings oscillate in two different directions simultaneously and asymmetrically the center of gravity is kept in the the center on average i assume something like this Their explanation below, im still stumped!!! Moser's Double Hairspring escapement with two opposing Straumann Hairsprings prevent the gravitational error from occurring in the first place. In a watch, the gravitational error disr
I tend to agree with what you say but in most cases the watch is worn in many positions, the tourbillon made inherently for pocket watches was to be placed in a single upright position for most of the time. I say a Zenith Christophe Colomb with a gyroscopic module that shifts with the movement of the hand would be apt for watches, as even the automatic gyroscopic module as on the JlC gyro tourbillon would have a certain amount of unnecessary amount of gravitational force acting on it when it is
... and frankly I do not know. Now if everything were optimized by a professional Regulateur today on the watchmaking scene . But those days are long gone and these, in their times, most highly paid persons in the industry have disappeared as well. So what is left - thinking along and about theoretical time-keeping? That the "idea" of accuracy and the "idea" of precision become just another marketing device. Whether they actually deliver that - is best left up to the company - and the community.
I always assumed that gravity also acted upon the pallet fork and escape wheel, and there was additional benefit to have these rotating with the tourbillon cage, at least in a watch held vertical in the plane of the balance. Andrew
Opinions on the below ? The new Audemars Pigurt Millenary Minute Repeater Escapement also uses a similar 'Double Hairspring' Have pasted two articles from two watch reporters i follow and respect. If one of the big three have put their faith behind it, must be something to it ? Article 1 The intriguing large balance wheel beats with 21.600 half beats per hour and has an even more impressive power reserve of 168 hours! Double hairspring design of Cabinet Piece Nr.5. Also introduced with Cabinet p
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