In the 1960s, flat movement were up-to-date. To ensure a long power reserve and good precision despite the flat and delicate construction, there was the idea to use two mainspring barrels in parallel for achieving higher torque.
Such a movement was the pretty rare “twin power” movement Favre-Leuba 270 from the caliber family 250/270, here in the basic version, which only shows hours and minutes.
The base plate of this 10 1/2 ligne movement shows, where the two mainspring barrels are located and that they are used in parallel and not sequential.
All important bearings contain rubies, except for the mainspring barrel. For a good quality movement, this is pretty standard.
Interestingly, the Favre-Leuba 270 uses a central minute wheel, a construction, which is not really known as flat-building.
The gear train is special due to its two mainspring barrels, which both engage simultaneously with a riveted intermediate wheel, which drives the center minute wheel. This wheel is followed by third wheel, center seconds wheel (whose axle is shortened on the caliber 270, since it does not carry a second hand) and finally the steel escape wheel.
A pretty large, three leg Glucydur balance is used as regulator. It beats slowly with 18000 A/h (adjustable only at the hairspring key directly) and is beared in two inhouse Favre-Leuba shock protections.
As escapement, a swiss pallet lever escapement with angled fork is used.
On the inner side of the barrel bridge, there’s a riveted intermediate wheel, too, which is responsible, that both mainspring barrels are wound at the same time.
The ratchet engages with the crown wheel and not with any of the ratchet wheels.
Interestingly, only the upper two mainspring barrel bearings contain rubies, but not the two lower ones on the base plate.
On the dial side, the edges are slanted to reduce some height, too.
Besides that, you see the usual things here like the shock protection for the balance wheel and the yoke winding system with its setting lever spring.
In the lab
Timegrapher resultSince the movement showed visible water damage and a broken balance wheel, it was obvious, that the timegrapher rates must be pretty poor.
Under these conditions, the measured values are even better than expected.
|dial up||+90 s/d||182°||1.0ms|
|dial down||+3 s/d||254°||0.0ms|
|crown right (12 up)||-6 s/d||169°||1.5ms|
|crown up (3 up)||+20 s/d||176°||1.1ms|
|crown left (6 up)||+10 s/d||169°||0.6ms|
|crown down (9 up)||+30 s/d||176°||0.4ms|
|Size:||10 1/2''' (measured: 23,4mm)|
|Number of jewels:||17|
Glucydur anular balance (three legs)|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|
|Construction type:||solid construction|
|Winding mechanism:||yoke winding system|
|Setting lever spring:||3 hole(s)|
Flume: K3 -|