One barrel, two barrels, ..... same power?

I found this definition of a Barrel: A drum that holds the Mainspring in a mechanical watch. The size of the barrel directly affects the length of the Power Reserve. Some watches feature a Double-Barrel which allows for extra long power reserve. The toothed rim of the barrel drives the train.

In many IWC watches, one barrel mechanism was enough to run 7 days power reserve. New mechanisms have now 2 barrels but same power reserve. Can someone help me to understand why two barrels are better than one?

Thanks

Dear Michael,
Thank you so much for the clear and comprehensive explanation.

Giovanni

Thanks Michael for the explanation.

• 1 !!!!

Very well explained Michael!

/Anders

Important fact that got forgotten here: The two-barrel calibres will have a higher clock speed. This is also an explanation for having two barrels.

I personally like the slow beat watches much better, i.e, the Jubilee Portuguese. It is a really classic, charming ticking in the fast world of today.

Because the 7 day movement are changing from the slow beat original to a fast beat at double the beat (I may be slightly wrong on that), does the frequency of the beat shorten the service interval?
I hope experts can advice on that!

Michael,

Thanks for the explanation! A few follow-on questions:
Do you know how the 2 mainsprings work together?
Are both powering the gear train simultaneously or one at the time?
Are both wound simultaneously by the winding mechanism?

From what I've read, accuracy issues resulting from the long mainspring was the main weakness on the previous 7 day movement. It would be very interesting to see the improvement with the new design quantified. I doubt IWC would disclose such information though.

Thomas

The slower beat on the previous movement was a detail that escaped me (no pun intended). What was the rate?

Thomas

This i found in the press release , and the former cal 51011 and 51613 beats at 21.600 A/h

PORTUGIESER DEBUT FOR THE 52000-CALIBRE FAMILY

The newly designed in-house 52000-calibre family with bidirectional Pellaton winding has already been selected for use in four models in the 2015 Portugieser collection. The new movements are equipped with two barrels. They not only supply the watches with sufficient energy for a 7-day power reserve but also drive complications like the new annual calendar or the perpetual calendar. Another innovation in this particular movement is the material: the winding pawls and the automatic wheel are made of black ceramic while the rotor bearing is made of white ceramic – to be more precise, zirconium oxide. IWC Schaffhausen is one of few watch manufacturers worldwide to use these practically wear-free, high-tech materials for parts in the movement.

The indexless balance has an increased frequency of 4 hertz (28,800 beats per hour). Combined with the Breguet spring, bent into shape using traditional techniques, this guarantees maximum precision. Only very few watches worldwide have such a high oscillation rate together with a 7-day power reserve.

Very important fact! With the faster beat calibre (4hz vs. 3hz)the mainspring needed for 7 days would have had to be even longer; this explains two barrels. Now was the higher clock speed, the two barrels, or both the result of a design change aimed at improving consistency? Originally the idea was to make an eight day movement and limit it to seven days to eliminate the loss of accuracy during that last day when the mainspring was almost all the way unwound.

Training on servicing 52000s for IWC watchmakers will start later this year and the details of this innovative new calibre are a closely guarded secret until then. Like everyone else, the only information we have is that gleaned from the IWC web site and Forum.
Regardless, watchmaking theory can give us some clues to the reasoning behind the choice of 2 barrels.
Increasing the speed of the balance can greatly improve the accuracy of a watch during wear. There are many reasons for this including much greater resistance to the adverse gravitational effects of sudden movement and quicker recovery from these effects.

There are 2 principle options for modifications, to the power side of the movement, available to increase the speed of the balance. Matching the train wheels to the new speed is necessary for both.
1.(mainly for indirectly geared barrel/train) Increase the torque through gearing and a thicker mainspring. This can cause premature wear and requires a larger diameter barrel and larger movement to house it.
2.(mainly for barrels directly driving train) Increase the speed of rotation of the barrel. This will reduce the power-reserve. To retain power-reserve a longer mainspring is required, again requiring a larger diameter barrel and larger movement to house it.
By using 2 barrels you can combine the best of both methods through slightly increasing torque and increasing speed of barrel rotation while preserving power-reserve and movement diameter.
As already noted in this thread, another important and intended benefit of 2 barrels is the smoothing of the torque curve over the full 7 days of power delivery.
I will try to post some more IWC specific info after training in a couple of months.
Leo

Thank you all for the valuable information provided which increase a lot my knowledge of mechanical watches.
Before reading the posts, I was of the impression that high frequency was associated with accuracy and vice versa. Now I understand that while they are related, low frequency does not necessary mean lower accuracy. Or at least, going back to Michael's reply, lower frequency does not mean lower accuracy as long as it's not the end of the power cycle.