Horological Meandering

dennis.raul
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Straumann Double Hairspring vs Tourbillion

HI,

Been stumped by this one for a while.

Have been trying to figure out which is actually better both technically and/or practically.

The Tourbillion is aesthetically and visually more appealing and most people like the way it looks (even though they don't understand it) and is visually more 'grand' and legitimate complication looking (apologise for the weird language, cant really put it in words)

The Double Hairspring escapement at first glance seems to people as ordinary as any regular escapement though technically it seems sound in principle.

Had quizzed an independent watch maker (cannot name the same) and they sent the following (see below)

As far as my limited knowledge in horology and physics allows me, my understanding is that for an Tourbillion to effectively negate the forces of gravity at various positions the watch might turn inot has a few caveats.

For e.g. - a 60 second tourbillion - the escapement has to complete one complete cycle (60 seconds) for it to effectively work, if the tourbillion escapemet moves around within the 60 second cycle it effectively cancels out the use of the cage.

Where as in the double hairspring escapement , due to the paired hairsprings negating the inertia of each other in a continues cycle and the center of gravity alternating between the two springs works in almost any position.

In the diagram below, it seems that the gravitational influence on an escapement with a Straumann Double Hairspring is miraculously low !

Can someone please help me out and shed some light on the same.

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.

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