The Breguet 7077, with Independent Blade Spring Powered Chronograph and More

April 26, 2015

Breguet’s “La Tradition” (Tradition) collection celebrates its tenth anniversary this year — I’ve already shared two of the three new additions to the line unveiled this year at Baselworld, including the Tradition 7097 Retrograde Seconds and the Tradition 7087 Minute Repeater Tourbillon. Today we look at my favorite, the Tradition 7077 Chronographe Indépendant 7077. Within its 44-mm white gold case, the 7077 essentially has two entirely independent movements (gear trains, escapements and springs (but not just any spring!)) for its two primary functions – regular timekeeping and chronograph timing. But the best of this watch is in the details. I’ll break it all down, starting with a short video which helps set the stage for what’s going on in this watch. Have a look below.

So you could see that there are two independent gear trains operating at different rates. First, the going train for the hours and minutes, regulated by at 3Hz (28,800) and having a power reserve of 50 hours via a single mainspring. The chronograph — entirely independent — is regulated at high-frequency 5Hz (36,600), but that’s not all, and here’s where it gets interesting! Normally, a second, independent gear train would require a second barrel + spring to provide the energy to power it. And along with this, a second crown to wind the chronograph barrel spring (in addition to the mainspring for the primary gear train). But not here!

With the Tradition Chronographe Indépendant 7077 model, Breguet has employed a new type of spring — a flexed blade spring — in place of a second mainspring. The blade spring – its energy brought to maximal potential by the actuation of the chronograph reset function — provides for up to 20 minutes of chronograph timing. A small trade off, in my book, as the system enables the user to start the chronograph instantly, without worrying about the energy available, because it will always be at its maximum.

The application of the blade spring principle by Breguet’s watchmakers has given rise to a number of ancillary innovations, first of which is a constant force mechanism in the form of a non-concentric going train that works with the blade spring so as to even out its non-linear torque (that is, the power it supplies drops off sharply over time). A patent has been filed for the entire spring and train assembly.

The chronograph function of the Tradition 7077 is controlled by two screwed pushers, symmetrically placed on either side of the case. Contrary to customary chronographs, one pusher is devoted to starting the measurement, while the other stops and resets the chronograph to zero. It is this zeroing action that flexes and arms the blade spring, thus preparing the chronograph for a new measurement. The titanium balance-wheel is also flanked by two brakes. The first, working off a cam, frees the balance wheel when the chronograph is started and then holds it when the chronograph is stopped. In this way the balance-wheel is always in the ideal position and instantly reaches its proper amplitude. This innovative mechanism is also protected by patent, according to Breguet.

In addition, though the 7077’s chronograph balance-wheel is higher frequency (which would typically suggest it to be of smaller diameter) it is the same size as the other balance; however, size symmetry has been maintained and Breguet has compensated by making the chronograph balance wheel out of lightweight titanium (also patented).

The 7077 will also be offered in rose gold. Pricing has yet to be announced.

An impressive assemblage no doubt! This is modern-day Breguet at its finest — signature design, with beautiful symmetry and mechanical exposure, and superb innovation.

words by Kyle Stults

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>