The 1815 “Homage to Walter Lange”, developed to commemorate the company founder who passed away a year ago, is based on a historic patent granted to Lange: the stoppable jumping seconds is deemed to be a precursor of the modern chronograph.
The technical features integrated in the 1815 “Homage to Walter Lange” include:
- The wheel train for the jumping sweep seconds located above the three-quarter plate
- The seconds jump controlled according to the flirt-and-star principle
- The trip mechanism that allows the jumping seconds to be started and stopped without interfering with the running movement.
The seconds wheel train located above the three-quarter plate
The jumping seconds is an old A. Lange & Söhne tradition. The first concept of a pocket watch with a seconde morte is attributed to Ferdinand Adolph Lange and dates back to the time around 1867. In his design, the seconds mechanism was located beneath the plate. Ten years later, the seconds wheel train was positioned above the three-quarter plate; Lange’s sons Richard and Emil filed a patent application for this arrangement. The ad-vantage of this configuration was that the watchmaker could remove the seconds mechanism without taking the movement apart.
In addition to the “creeping” small seconds, even the first Lange pocket watches with jumping seconds had a large sweep seconds hand that tracked the minutes in precisely 60 steps. The hand was started and stopped with a pusher. As in a chronograph, this process was controlled with a column-wheel arrangement. The seconds mechanism with a jumping hand in the calibre L1924 of the 1815 “Homage to Walter Lange” – visibly located on the three-quarter plate – operates according to the same principle described in patent No. 182 dated 1877.
Control of seconds jump
As in the historic mechanism, a flirt and a star were the elements that controlled the seconds jump, the conversion of the six semi-oscillations of the balance into one hand step per second. Together with the escape wheel, the five-point star – located on the escape wheel arbor under a transparent jewel bearing – rotates about its own axis once every five seconds. After each full second, one of the tips of the star liberates the tensioned lever arm, which watchmakers refer to as the “flirt”. It then swiftly rotates by 360 degrees before it is stopped by the next tip of the star. This rotation is transferred to the central seconds hand via the seconds wheel train, causing it to advance to the next marker.
The start/stop mechanism for the jumping seconds
The trip mechanism described in the 1877 patent that allows the jumping seconds to be started and stopped is integrated in the calibre L1924 in a slightly modified form. If the pusher is actuated while the central seconds hand is running, the V-shaped switching lever released by the column wheel blocks the flirt including the entire seconds mechanism while the wheels of the movement continue to run.
The connection of the movement with the seconds mechanism is established by a click mechanism. The ratchet wheel is firmly connected with the wheel train; with two clicks and their springs, it transfers torque to the click wheel. The pallets of the clicks engage with the ratchet wheel and thus allow power to flow from the mainspring barrel to the seconds mechanism. When the flirt is stopped, the wheels of the seconds mechanism are blocked but the pallets of the clicks alternately drop off from the teeth of the ratchet wheel that continues to turn slowly. This is necessary because otherwise the whole movement would be stopped as well. This ingeniously simple design makes it possible to power the movement and the stoppable jumping seconds with only one mainspring barrel.
When time came home – 1815 “Homage to Walter Lange”
