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Discussion Starter #1
Hi guys.
Here is another little beauty I managed to get hold of, a twinpower manual wind in almost NOS condition with the original box and paperwork/receipt.
I am tyring to contact the original owner for a bit more info to no avail.
I am also not sure whether the crown is original as its not signed but.... This watch keeps almost perfect time lost about 2/3 secs per day and has run without winding for 34 hours now non stop lol.
PS sorry for the poor quality photos (bad lighting)







Thanks.
 

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your dial will need a small cleaning, movement wise you have a very good movement which is a twin barrel handwound based AS movement exceeding 46 hours of power reserve
 

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Discussion Starter #4
Something else I forgot to say is that it seems to take a really long time to wind, at first I thought it was broken lol.
 

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I was disagreeing with Georges' suggestion that the movement was an AS - Adolf Schild - product. As I understand it, it was made in-house by Favre-Leuba. :)
 

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Hi bluestifford,

after my oppinion you got one of the best manual wind movements ever made.
Here some details:
bidfun-db Favre-Leuba_253: Favre-Leuba 253

Regards, Roland Ranfft
Hi Roland,
that's interesting- what makes it so special that You rate it like that? I know You are referring to technical design rather than then finish. But - the twin barrel set aside - what are the criteria? I mean - I never heard of a FL setting any record in accuracy, f.x.
Olof
 

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Hi Olof,

there are many reasons, and it is pretty complicated. Already the
ultra-short explanation is long:

1) Easy assembly.

I guess it is possible, to put all parts in a box and shake it, to assemble
this movement. More detailled: If you set all wheels into the base plate,
and cover them with the train bridge, all pivots find their holes without
troubles. Moreover there are only few screw sizes - nearly no chance to
do wrong. All in all I've never seen a movement which is easier to assemble,
on one hand due to intelligent design, on the other due to manufacturing
precision. The same is often told about Rolex movements, but there it is
a fairytale, and for the Twinpower it is reality.

Even the two barrels are easier to handle than one conventional. They
have a center bushing as high as the barrel as bearing. This is not only
more durable than the common holes in bottom an cover, but also makes
the cover(s) superfluous.

2) Built in accuracy

The Power available for the balance is proportional to the volume of the
barrel or here of both. As two barrels use the space in the movement more
efficiently than one, there is more space for a big balance, and moreover
the higher barrel volume allows to make the balance heavy. Both are kinds
of built in accuracy.

Moreover the precision of the escapement bearings care for accuracy.
And in this aspect a balance bridge is better than a cock. But this feature
is even found in humble Rolex designs.

3) Durability

It is easy to understand that partitioning the power on two barrels will
reduce wear substantially. But this is the most unimportant part of the
story. Two barrels can be arranged in a way that bearing pressures are
reduced to almost zero. Take this pic for explanation:



Between both input gears (lower) and output gears (upper) there are tiny
wheels. Now imagine that the barrel bridge is flipped onto the base plate.
Then these two wheels are precisely on on top of the other. For the left
barrel this means that input torque and output torque are applied to nearly
the same point. It is easy to calculate that the resulting bearing preasure
is ideally zero. For the right barrel the calculation is more complicated, but
even there the bearing pressures are orders of magnitude lower then for
every single barrel design.

And now the cherry on the cake: Input and outpt gear rims of the barrels
are arranged very near each other directly under the bridge. So, if ever
the torques result in a residual bearing pressure, this is restricted to the
bearings on the brige side. And although wear is already no issue, two
jewels are applied at this place.

4) Slim but stable

Usually thick and big movements are regarded as solid and accurate.
This movement shows that inteligent design brings these features and
much more into a just 3mm high movement.

No need to keep this all in mind. Simply believe that the step from one
barrel to an indelligently designed twin barrel has the same dimension like
the step from a one-cylinder tractor to a 12 cylinder formula-I.

Regards, Roland Ranfft
 

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Roland:

You should archive that summary in your movement pages!

A related question: What is your opinion of the Russian Slava dual barrel movement?
 

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Hi Brian,

I guess the designers copied the Favre Leuba, but didn't understand the
principles of the design. So the inevitable advantages of two barrels apply:
Big balance, efficient use of movement space. But the degrees of freedom
to make it durable were just purely realized, just by accident.

The Favre Leuba designers had good reasons to give input and output gear
rims of the barrels nearly the same diameter, to arrange both narrow under
the brige, and engage the click to the crown wheel instead of one input
wheel of a barrel. All these features minimize wear, and are missing in the
Slava design.

Regards, Roland Ranfft
 
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