skyeriding
901
My understanding of the Piguet 1185 as follows:
Fundamentally, the isolator mechanism work the same way for most rattrapantes - an extra gear with a pin is stacked onto the rattrapante wheel; the pin pushes the rattrapante lever out of the way to avoid drag/friction around the heartcam when in use.
Here's a photo of the Piguet 1185 with isolator I found:
And with reference to Lange's double split diagram:
The summarised explanation is that the brass gear in the Piguet photo is the disengagement wheel (1), while the rattrapante wheel itself is (2). The column wheel (4) coordinates an extra disengagement ratchet (5) via the lever (3). When rattrapante is activated, lever (3) flicks outwards and rotates (1) to activate it.
Rotation of (1) forcefully pushes the spring loaded lever on the rattrapante wheel out of the way, as seen in direction of blue arrow:
In diagram above, (4) pushes against lever (2); (2) is the lever that drags around the rattrapante heartcam in a "regular" rattrapante. This drag causes extra resistance load onto the main geartrain of the watch - therefore which may affect amplitude of the rest of the watch (correct me if wrong!)
Why am I going into this? Essentially, the Lange works the same way (well, the Piguet is a Class 3 Lever ilke a Habring, while the Lange DS is a typical Class 1 scissors Lever...). The main innovation in my opinion, is that Lange integrated two rattrapantes into one. You raised a very good point - Lange had to have two simultaneous isolators for each set of rattrapantes (minute, and seconds). Each rattrapante column dragging of heartcam would result in massive resistance - with the minute register, there now is a dragging rattrapante lever running seconds hand that has to further flick every minute an extra rattrapante column with another set of dragging rattrapante lever; that is a monstrous load spike onto the mainspring!
My point being, I wouldn't say that Lange were the first to come up with this ingenious system - however they did the ingenious engineering of having two into a single chronograph which is a deeper technical challenge than it appears to be...Something that no one else to my knowledge has done even till today.
I wouldn't dismiss having an isolator as merely an extra luxury; its always a nice thing to have to prevent unnecessary dragging of the rattrapante lever onto the heartcam (therefore avoiding extra load; wear is arguably insignificant considering the quick resets that is done in a fraction of a second when the rattrapante brakes are released and the rattrapante hand resets..)..Its another layer of mechanical refinement to the rattrapante while adding thickness, demonstrates a technically refined solution to the dragging problem. Whether they are more reliable in the long run from extra moving parts I cannot answer however...
Regards,
skyeriding
This message has been edited by skyeriding on 2016-03-02 05:25:00 This message has been edited by skyeriding on 2016-03-02 05:26:23