THE LANGE 1815 UP and DOWN:
THE CALIBER L942.1

Part 2

BY WALT ODETS











































































































POWER RESERVE DISPLAY


The power reserve display is not only a traditional feature on some Lange pocket watches, it is a very useful complication. The display is a reminder that a watch has or or has not been wound in the morning, a reminder to wind when the watch has been sitting unworn, and is an invaluable convenience during positional adjustment and rating of the watch. As seen from the unassembled top plate (right), only the upper differential wheel (1), intermediate wheel (2), mainspring barrel (3), and ratchet wheel (4) are visible.

Removal of the the upper differential wheel (right, 1, shown inverted) reveals the heart of the power reserve mechanism. This is the differential axle (2). The lower differential wheel (3) is now also visible. The intermediate is shown at (4).

 

Because the power reserve display (in the case of the 1815) must rotate clockwise during winding and counterclockwise during running, the stem and crown must be separated from each other. Otherwise the crown would rotate during running of the watch. As illustrated right, the upper and lower differential wheels both power the differential axle through planetary (or satellite) gears attached to the differential axle plate. The differential axle (1) is shown with the lower differential wheel (2) attached. The satellite gear on the lower side of the axle plate (3) is driven by the central gear on the lower differential wheel (not shown, under the axle plate). The satellite gears on the top surface of the axle plate (4) are driven by a central gear on the underside of the upper differential wheel. The lower extension of the differential axle actually drives the power reserve display (via two intermediate wheels).

 

A schematic of the power flow and direction of rotation of the power reserve differential is shown right. Note that the upper differential wheel (2) is driven directly by the ratchet wheel. The intermediate wheel (1) transfers power from the barrel to the lower differential wheel. When the watch is wound, the upper differential wheel turns the differential axle counterclockwise. When the watch is running, the mainspring barrel turns the differential axle clockwise. Driven by the differential axle, the power reserve display rises and falls respectively.


 

THE BOTTOM PLATE

On the bottom plate (dial side) of the movement we find a friction-fit gear (left, 1) on the extended differential axle pinion. An intermediate wheel (2) drives the indicator wheel (3) that actually carries the power reserve display hand. It is interesting that these three components, alone, account for the increase in thickness of the movement over the non-power reserve version. The parts are accommodated in machined recesses in the back of the extraordinarily thick 925 silver dial (left), thus saving Lange the cost of producing a new main plate for the power reserve version of the movement. A 0.38 millimeter increase in the thickness of the case bezel accommodates the thicker dial. While the increase in the thickness of the watch is objectively nominal, the proportions and aesthetic of the 1815 Up and Down are quite distinct from those of the watch without power reserve.



Also on the bottom plate, the elegantly simple keyless and motion works is visible. The construction of these mechanisms is utterly traditional. Interestingly, the dial side of the movement would be very difficult to distinguish from a very high-grade Swiss watch. The German aesthetic so obvious on the top plate, is extremely subtle here. The matte finish of recessed areas of the plate (arrow) are among the few clues.


THE ESCAPEMENT

The escapement of the caliber 942.1 is a traditional lever escapement of immaculate finish. The balance, a two-spoke Glucydur unit, is equipped with a flat spring. On the top of the balance cock, a fine regulator screw with swan’s neck spring is provided. A locking screw on the movable stud carrier allows adjustment of beat with the regulator screw without removal of the balance from the watch. Unfortunately, I found the performance of this mechanism relatively unreliable because of excessive play in the parts. Because temperature compensation is now provided by the Nivarox balance spring, rim screws are no longer necessary for this purpose. They might be used to poise the balance, but the laser cut on the underside of the balance (right, arrow) suggests that this is, in fact, a computer-poised assembly. Unfortunately, decorative screws only diminish the potential performance of such an escapement.

In practice, the extraordinarily good finish of parts and careful adjustment of this ordinary escapement produce excellent results. On my sample of the 1815 Up and Down, beat error, daily rate, and amplitude were all precisely to specifications. The largest rate variation between positions was five seconds, a very good performance.













































CONCLUSIONS

It would be difficult to argue with the assertion that the Lange 1815 Up and Down offers extraordinarily high quality materials, construction, and execution.

While much of the beauty of the Lange derives from its traditional materials and appearance, the adherence to tradition limits what this watch–from an essentially new company–could have been. Although the manufacturing processes probably involve technical innovations, the utterly traditional engineering of the caliber 942.1 involves nary a single piece of new thinking and a considerable amount of technical backpedaling. The Up/Down is essentially a miniaturized replica of a 19th century German pocket watch. Among features glaringly absent in a watch of this quality are an adjustable mass balance and Breguet overcoil. Other Lange calibers–those with date, as well as the superbly constructed automatic caliber L921.2–offer somewhat more with regard to innovation, although their escapements also employ flat springs and a screwed, laser-poised Glucydur balance.

If traditional German charm, beautiful execution, and robustness in a simple hand-wound watch are to your tastes, you cannot equal the 1815 with a watch from anyone else. If honest, function-driven, contemporary engineering or technical innovation are also important, consider a Lange automatic, the recent Chopard caliber 1.96, or some of the free-sprung caliber 215, 315, or 240-based Pateks. The Lange Up/Down is its own kind of quirky, old-new masterpiece. It is not, however, a contribution to furthering the technical development of the mechanical watch.














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