A. Lange & Söhne is not the largest watch manufacture and they prefer to keep it that way. Nevertheless, in name and by way of reputation, they are amongst the titans of the watch world.
Precision is an attitude at their base of operations in Glashütte, Germany that becomes ever more evident with every step you take past the A. Lange & Söhne doors.
The question, when it comes to the A. Lange & Söhne Double Split chronograph is this: is it truly new or just another take on an old subject? In fact, it is truly a new idea that marks the evolution of a classic watchmaking complication.
Basically, the Double Split is a chronograph meant to record periods of time, events, with great precision. In the mid 1800’s the idea for a split seconds chronograph emerged. This mechanism allowed two events to be compared via the same watch. This is useful for any kind of racing activity. But there was one drawback to all these previous split chronographs: they could only record comparative differences of one minute or less. If you had two events that might elapse over the course of more than one minute, you had to mentally keep track of the minutes. By way of contrast, the Double Split allows a comparative record of two events to be precisely generated for up to 30 minutes.
Sensibly, the Double Split has two sets of chronograph hands for recording two separate events, or only one event if that is your requirement. At the center of the dial are the usual hour and minute hands, and concentric to these are two chronograph seconds hands. To the lower left are two chronograph minute recording hands sharing the same chapter ring (sub dial). A closer look reveals that the seconds’ recording hands are of different colors - the upper white and the lower gold - while the minute recording hands are also of two different colors (blue and gold). Contrast to the respective dials, and sub dial colors, is the reason for this.
As it is with all split chronographs, there is a third push piece involved in the operation. Besides the usual two push pieces located at 2 o’clock and 4 o'clock, a third is located at 10 o'clock. It is this third button that controls the "split" action of the chronograph. Pushing the button at 2 o’clock sets the chronograph to action, with both seconds and minute recordings synchronized with each other, a typical way of recording a single event. Now a simple push of the button at 10 o'clock stops one of the seconds and minute recording hands to record the first event, and another push brings all the chronograph recording hands back into synchronization. This process can be repeated as many times as required.
But it is not merely the ability to record multiple events within split seconds and minutes that makes the A. Lange & Söhne Double Split special. An ingenious double clutch mechanism, controlled by two small hammers and two small heart-shaped cams, ensures the A. Lange & Söhne Double Split will not suffer any of the liabilities all other split chronographs have faced.
In drawing #1 we get an overview of the split mechanism. The two gold-colored wheels are the seconds- and minute-recording wheels that can be stopped and started again while the main chronograph continues to function. The central seconds wheel has very fine and barely visible teeth at its perimeter, while the minute recording wheel has 30 coarser teeth because the double split has a 30-minute counter on the dial side. Also notice the cutaways and the light blue details. These details show the position and movement of the various parts when the split has been activated and has recorded an intermediate event, while the solid color details show the same parts while they are operating in synchronization with the main chronograph function. We will explore the individual components in much greater detail as we move along.
The Double Split requires two column wheels to operate the main chronograph functions and the split functions. At "A" is the main chronograph column wheel. Look closely because it is more of a crown that turns at precise increments, as desired, by each press of the main chronograph function buttons, thus starting, stopping, and reseting these functions. Now have a look to see that column wheel "B" is responding to the owner's requirement to stop and record a secondary event (the split recorder). These operations are the basic part of every split seconds chronograph.
| Now we "split" from the ordinary and examine two very special features of the Double Split chronograph. In order to record two separate events – seconds and minutes each – there needs to be two chronograph seconds hands and two minute-recording hands. Rather than spread hands all over the dial in a cluttered array,A. Lange & Söhne has chosen very wisely to keep like-minded hands together in central locations. To explain the first special feature, |
At "C" is a pipe (tube) that carries either a minute-recording hand or seconds-recording hand. Remember that there are two of these mechanical marvels in the watch. And "D" is a shaft that passes through the pipe and carries another corresponding hand.
The split control mechanism has been removed for easier viewing and understanding in the photo above. When the split mechanism is called upon, by pressing the split button on the case, pressure is applied to shaft "A" which in turn pulls hook "B" that rotates crown wheel "C" 1/16th of a turn, and jumper spring "D" holds the crown wheel stationary. Two arms, "E" and "F" form a set of scissor arms. These scissor arms will grab and stop the split-seconds wheel (you can see this very clearly in drawing #1) when called upon to record an intermediate event.
This action must be very swift in order to stop the seconds hand at a fraction of a second but also gentle enough not to unsettle the hand so it shows a false reading. It is, I can attest, a very fine skill to adjust the proper operation of a split chronograph. Stopping the split-seconds hand is the first operation that must be accomplished in the Double Split, but not the only. The two pins "G" and "H" will be responsible for the clutch actions that will be examined towards the end of this article.
I save the most interesting aspect of the A. Lange & Söhne Double Split for last. As mentioned a couple of pages ago, each set of chronograph recording hands, minutes and seconds, must be either coupled together (as in recording a single event) or decoupled (as when the split function is called to action for a secondary event). And, when the split function is called out of action, the recording hands (minutes and seconds) must again become instantly and perfectly synchronized with their counterparts. This latter point is extremely important.
In order to record two separate events, there needs to be a pair of clutch systems, one for minutes and one for seconds. In the photo above we can see these clutch mechanisms, "A" is for the minutes and "B" for the seconds recording. To give you a better perspective the clutches have been removed (out-takes, left) and shown from the top and the bottom. Their function will become clearer in the following drawings.In the drawing above are the hammers "A" and heart cams "B" as mentioned earlier. In the upper drawing, the minutes- or seconds- recording hands are in synchronized mode, coupled since the hammer is in direct contact with the heart cam and held there semi-rigid via the force of the gold-colored spring. In the lower drawing, they are not synchronized, uncoupled since the hammer has been held apart from the heart cam. Think of it this way, in the upper drawing, you are strolling along with your friend, synchronized, but suddenly your friend needs to stop while you keep on moving (lower drawing). At a further point down the way you agree to get synchronized again with your friend. Magically, at the touch of a button, your friend is at your side again. When the hammer falls to the heart cam, there is no other possibility since the heart cam is eccentric and cannot avoid the path of least resistance.
Something more. All split chronographs suffer a liability when the split function is being used, the hammer is in constant contact, dragging, around the heart cam. The A. Lange & Söhne Double Split has avoided this drag factor by totally decoupling the hammers and heart cams while the split function is in use.
Going back to the operation of the clutch systems, once the split-seconds wheel has been grabbed and stopped by the scissor arms, the clutches must be disengaged in order to stop the flow of power to both the split minute and seconds hands. This must happen after the scissor arms do their bit, but only a fraction of a second later. So here, in the photo above, we get a view of the clutch mechanisms and their engagement and disengagement operation. "A" is the lever that controls the engagement/disengagement of the clutches. There are two sets of three teeth (B and B') at either end of the lever "A" that are responsible for hooking onto the very fine teeth of the clutch release wheels C and C' and turning the wheels in a counterclockwise direction about 30 degrees and thus disengaging both clutches instantly and simultaneously. Of course, when the split button is pressed again, the scissor arms release the split-seconds wheel, the clutches are engaged, and the split hands (minute and seconds) are instantly in perfect synchronization with their partners that have been happily recording the main event undisturbed. Imaginative and ingenious indeed!
One final observation. We’ve talked a lot about the how the Double Split works. There is however a lot more to a fine watch – the time consuming hand-work that goes into the finishing of the components, each and every miniature part. Please have a very close look at this photo, at the graining, beveling, polishing, and even the sides of the levers and springs and try to imagine the time it takes a person to accomplish these standards of personal artistry that only human hands can bring to life.
I strongly suggest you have a look at this animation provided by A. Lange & Söhne, you will certainly get a clearer idea of the A. Lange & Söhne Double Split and its special qualities.
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