A. Lange & Söhne Lange Double Split – World’s First Flyback Chronograph with Double Rattrapante

Introduced in 2004, the LANGE DOUBLE SPLIT chronograph watch from A. Lange & Söhne features two rattrapante hands – one for the seconds and one for the minutes to be stopped. What’s more, both chrono hands and both rattrapante hands are flyback hands.

The intricate complication of a rattrapante sweep-seconds hand in a chronograph has always been an awesome horological accomplishment for short-time measurements. Unfortunately, the possibility of taking a lap-time reading with the rattrapante sweep-seconds hand during an ongoing measurement was restricted to the 60-second scale and thus to laps of less than one minute.

In the LANGE DOUBLE SPLIT, the principle of the rattrapante sweep-seconds hand has been extended to the jumping minute counter. This means that for the first time ever, comparative lap measurements of up to 30 minutes  are now possible in a classic, purely mechanical wristwatch. Also, the act of measuring a lap time does not have to be at the expense of a loss of amplitude when the chrono sweep-seconds hand continues to revolve while the rattrapante sweep-seconds hand is stopped. This is prevented by a patented disengagement mechanism developed by “A. Lange & Söhne”.

The LANGE DOUBLE SPLIT was inspired by the technical refinements once before integrated in a Lange double-rattrapante pocket watch that dates back to the late 19th century.

Buoyed by the success story of the DATOGRAPH that began in 1999, the engineers systematically evolved an already ingenious timekeeping instrument to create an incomparable horological masterpiece in a platinum case with a diameter of 43 millimetres. They endowed this landmark timepiece with all of the major innovations and complications that since then have been devised at the Lange manufactory in Glashütte.

This includes a new balance wheel developed in-house by Lange. Designed for a frequency of 21,600 semi-oscillations per hour, it is equipped with eccentric poising weights instead of inertia screws. It is powered by a top-quality balance spring which was also developed in-house by Lange and is manufactured on site. It, too, features a technical novelty: It is not attached to a hairspring stud but instead is secured by a patented balance-spring clamp.
Inaugurated in 2003, the manufactory’s new Technology and Development Centre has been pursuing the kind of fundamental research that Richard Lange, the oldest son of company founder Ferdinand Adolph Lange, embarked upon in 1930 with his patent No. 529945 concerning a “metal alloy for balance springs”, an invention that since then has found global acceptance. He discovered that the sensitivity of hairsprings to temperature fluctuations could be reduced and their flexibility enhanced with the addition of beryllium.  Since establishment, Lange is one of only a few companies in the world that master the latest-generation processes needed to manufacture balance springs. All these assets are embodied in the LANGE DOUBLE SPLIT, a very special and exclusive horological accomplishment.


With its manually wound calibre L001.1 movement, the LANGE DOUBLE SPLIT is first and foremost a watch that indicates the hours and minutes on its two-tiered black solid-silver dial, the seconds on its silvery subsidiary dial on the left-hand side, and the power reserve with an indicator beneath the Roman “XII”. The small seconds dial, the also silvery 30-minute counter dial of the chronograph on the right-hand side and the up and down indicator constitute the corners of an equilateral triangle, a typical characteristic of the architecture of Lange dials.

The chronograph function: When the owner presses the start/stop push piece of the chronograph, subtly rounded to accent the classic circular case, the LANGE DOUBLE SPLIT becomes a “watch in the watch”. This action sets the slender gold-plated chrono sweep-seconds hand in motion. When the same push piece is pressed again, the hand stops. When the zero-reset push piece at 4 o’clock is pressed, the sweep-seconds hand returns to the 12 o’clock position.The chrono minute counter: Each time the chrono sweep-seconds hand crosses the 12 o’clock marker – not before and not afterwards – the gold chrono minute counter advances by one minute marker. Thus, in the “grey zone” on either side of the zero passage of the sweep-seconds hand, there is never any uncertainty as to the accuracy of a measurement.

The flyback function: While the chronograph mechanism is running, both chronograph hands can be instantly reset to zero by pressing the push piece at 4 o’clock. When this push piece is released, the chrono sweep-seconds hand restarts immediately. Its minute counter will advance by one marker precisely one minute later. This so-called flyback device makes it possible to initiate a new measurement without delay. With simple chronographs, the same effect requires the actuation of the start/stop push piece to stop the hands the actuation of the zero-reset push piece to return the hands to the home position, and the renewed actuation of the start/stop push piece to start the next measurement. The flyback mechanism bundles all of these interventions into one actuation. The idea for this mechanism dates back to an epoch in which pilots needed to co-ordinate speed, rudder position, and time to fly curves, and fast reactions were needed.

The rattrapante function: A further hand is located above the chrono sweep-seconds hand and over the chrono minute-counter hand. The rattrapante sweep-seconds hand, made of rhodiumed steel, hovers over the chrono sweep-seconds hand and the blued steel rattrapante minute-counter hand lies a hair’s breadth above the chrono minute counter hand. During an ongoing time measurement, the rattrapante hands can be used for a separate lap time measurement at any given moment. This is how it works: When the start/stop push piece at 2 o’clock is pressed, both pairs of hands are set in motion simultaneously. The rattrapante push piece at 10 o’clock is pressed to measure the first time. The rattrapante sweep seconds hand stops instantly, displaying the measured lap time. For the second measurement, the start/stop push piece is pressed to stop the still-running chrono sweep-seconds hand. This allows the owner to note the second lap time as a separate result or to compare it with the first lap time. If more than two consecutive measurements are to be made after the hands have been collectively set in motion, the following procedure must be observed: The first lap time, stopped with the rattrapante push piece, must be memorised or written down. The renewed actuation of the push piece causes the rattrapante sweep-seconds hand to instantaneously catch up with the still-running chrono sweep-seconds hand. This process can be repeated as often as desired, as long as the chrono sweep-seconds hand is in motion and the aggregate time measurement has thus not been interrupted.

The rattrapante minute counter: The LANGE DOUBLE SPLIT has a chrono minute counter as well as a rattrapante minute counter. For this reason, the rattrapante time measuring range is not just 60 seconds as in conventional chronographs, but 30 minutes. Technically, this was achieved by duplicating the construction of the chrono/rattrapante wheel pair. In other words, the minute-counter wheel has a through bore that accommodates the shaft of the second rattrapante wheel. Since the LANGE DOUBLE SPLIT contains a chronograph mechanism with a precisely jumping minute counter, the rattrapante minute counter jumps as well. A lever mechanism developed by Lange especially for this purpose assures that it advances by only one minute at a time, at precisely the right moment.

Reference lap time measurement: If a lap time measured with the rattrapante hands is required as a reference time for further measurements, it can simply be “stored”. This is done by leaving the stopped rattrapante time untouched and by resetting the chrono sweep-seconds hand with the start/stop push piece followed by the zero-reset push piece – or instantaneously with the zero-reset push piece (flyback). The normal chronograph function can now be used to measure a reference lap time and compare it with the time displayed by the rattrapante hands. This process, too, can be repeated for any number of further reference lap times that might be needed.

Fastest/slowest lap measurement: Technology buffs will appreciate another function that allows the identification of minima and maxima – the fastest or slowest lap of all laps measured, for instance. To determine the fastest lap of a series, the first lap is stopped with the pair of rattrapante hands, the second with the pair of chronograph hands. At this point, both times need to be compared. If the lap time displayed by the chronograph hands is the shorter of the two, this value must be stored as the minimum, simply by pressing the rattrapante push piece twice in a row. The first actuation causes the rattrapante hands to line up with the chronograph hands, the second actuation freezes them there. If the lap time indicated by the rattrapante hands is shorter, no action is required. The hands can stay where they are.

The next lap can be timed – and if applicable, stored – by resetting, restarting, and restopping the chronograph hands. Conversely, to determine the slowest lap, the rattrapante push piece must be pressed twice if the time measured by the chronograph hands is greater. In both cases, the value displayed by the rattrapante hands at the end of a series of measurements is the extreme (maximum or minimum) of all stopped times.

The disengagement mechanism mentioned above, a Lange proprietary development, prevents the so far technically unavoidable amplitude drop in conventional constructions when the chronograph hands are running but the rattrapante hands are stopped. Normally, the sustained contact between the still-running heart-shaped rattrapante cams and the rattrapante heart levers creates friction losses and torque fluctuations. In the LANGE DOUBLE SPLIT, these annoying phenomena have been eliminated because disengagement wheels on the rattrapante centre wheel and on the rattrapante minute wheel separate both rattrapante heart levers from the still rotating heart-shaped cams. This has a beneficial influence on the rate accuracy of the movement. This makes the habitual use of the fascinating and very practical rattrapante function a delight that entails no regret, all the more as most of the complex mechanisms of this mechanical marvel can be admired through the sapphire crystal caseback. It is hardly disputable that the LANGE DOUBLE SPLIT will push the emotions of connoisseurs around the world quite far up on the open-ended enthusiasm scale.

Technical details

Movement
Lange manufacture calibre L001.1, manually wound;crafted, assembled, and decorated almost entirely by hand to the highest Lange quality standards; precision adjusted in five positions; plates and bridges made of untreated cross-laminated German silver; balance cock engraved by hand;Number of parts: 465;Jewels: 40;Screwed gold chatons: 4;Escapement: Lever escapement;Balance: New, shock-proofed Glucydur balance with eccentric poising weights; proprietary top-quality balance spring with an attachment (balance spring clamp) for which a patent registration has been filed; frequency 21,600 semi-oscillations per hour; precision beat adjuster with whiplash spring;Power reserve: 38 hours when fully wound.

Functions
World’s first flyback chronograph with double rattrapante, controlled by classic column wheels; precisely jumping chrono minute counter and rattrapante minute counter; flyback function; disengagement mechanism; hours, minutes, small seconds with stop seconds; power-reserve indicator; cumulative and lap-time measurements between 1/6th of a second and 30 minutes, tachometer scale

Operating elements
Crown for winding the watch and setting the time; two push pieces for operating the chronograph; one push piece for operating the rattrapante.

Case, dial & strap
Case: Diameter 43 mm, platinum
Glass and caseback: Sapphire crystal (hardness 9)
Dials: Solid silver, two-tiered, black
Hands: Yellow gold, rhodiumed gold, blued steel and rhodiumed steel
Straps: Hand-stitched crocodile straps with solid-platinum Lange prong buckle

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