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The Crown-Operation-System (COS) Chronograph

 

One of the iconic Habring2   watches, and one of those that really convey the message of the producers. By modifying the Valjoux base movement such that the pushers could be omitted (Chronograph is entirely controlled by the crown), the watch gains elegance and simplicity. Furthermore, fewer serviceable parts are needed, and two holes in the case are missing, resulting in less risk of failing seals.



Here I'd like to show a version where seconds and minute counter both are located on the central axis, and thus indicate elapsed time in the normal time display:



The following graph shows how the system is implemented. An additional wheel on the crown axis is interlinked with a pawl that directly (without the need for a column wheel or a cam/lever construction!) operated the chronograph:



The graph also nicely demonstrates what would happen if you pull out the crown for setting the time: wheel and pawl would simply disengage.

The entire beauty and brilliancy of the construction is immediately apparent once you compare it to a standard ETA Valjoux 7750 movement (left):



Back to the movement (ok, this one here is a bit turbo-charged... more later!):



The COS pawl here is disconnected from the COS wheel. At the 12 to 01 o'clock position you can see the COS spring:



The reset cam:



The elegance of the watch is met with a vibrant design the excites with voluptuous shapes and colours:





The optical benefit of COS is highlighted if you inspect it from the side:



The movement is of course visible from the back, here the handwound version (automatic exists as well):



Finally, on the (=my) wrist:



This message has been edited by Magnus Bosse on 2012-04-28 09:42:37

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