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Horological Meandering

We are clever guys, let's think this through

 

There’s a 7750 Chrono system shown here (in the midst of an IWC watch) The crown is at 3 and the minute counter below 12; hours above 6.




Ignoring all the start / stop functions, here is its driving system. As Art noted, revolving gear 8447 with a spring arm 8449 nudges intermediate gear 8844 one tooth, and that moves the minute hand in a semi-instantaneous fashion. The long spring 8495 is adjusted (by turning screw 8804) when the watch is serviced to align the hand with the 0 minute marker.

The heart-shaped cams you see on several gears are used in the reset-to-zero process.



FRANKLY FOR MOST OF US, THIS IS ROCKET 🚀 SCIENCE! Feel free to forget you’ve seen how the magic happens...

And for the skeptics, here’s how a chronograph can be used:







Cazalea

PS - giving the hand a nudge every 60 seconds might require less energy than continual running?






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20 Comments view entire thread 

For the consideration of chronograph caliber enthusiasts...

 
By: halgedahl : July 8th, 2019-06:36
Good day chronograph enthusiasts! Though some may argue that a rotating bezel is a far simpler solution to most daily time-keeping requirements (parking meter, 3-minute egg, et al), we who are devoted to this significant advance in horology will always ar... 

Something to consider

 
By: jmpTT : July 8th, 2019-07:26
Never mind the minutes. I’ve often thought that the hours register could jump as well. So why not? The reality for most mechanical chronographs is the jump of the minutes register is semi-instantaneous, not instantaneous. The irreversible jump is engaged ... 

Very interesting! This is just the sort of info I was looking forward to. And yes, certainly I have noticed the "semi-instantaneous" nature of the jump. Lang, eh?

 
By: halgedahl : July 8th, 2019-07:36
Wouldn't you know. I'd love to know more abot the difference, and how this was achieved. Do you have a suggestion of where might I look? Many thanks for your response! Have a fine day. (Second, never mind the pun, your notion that the hour, too, might "ju... 

Well, I did...results surprised me

 
By: jmpTT : July 19th, 2019-15:02
Stopped two watches between 59 and 60s. Lemania 2320 - minute hand on register stops fractionally between 0 and 1 min. Glashutte Cal 61 - minute hand completes jump to 1 min, once sequence starts. For what it’s worth, it seems that different semi-instanta... 

My rudimentary understanding of chronograph movements is that typical 'jumping' minute counters . . .

 
By: Dr No : July 8th, 2019-15:07
. . . are actuated by a spring, which is relatively simple to implement. Continuous operation would imply a drive-train, which would be more costly to implement, and possibly expend more energy. Art

We are clever guys, let's think this through

 
By: cazalea : July 8th, 2019-23:39
There’s a 7750 Chrono system shown here (in the midst of an IWC watch) The crown is at 3 and the minute counter below 12; hours above 6. Ignoring all the start / stop functions, here is its driving system. As Art noted, revolving gear 8447 with a spring a...  

Mike, we can always "count" on you. Many thanks for this cut&paste which has taught me (us?) quite a lot about the amazing usefulness of the chronograph! Now to

 
By: halgedahl : July 9th, 2019-07:32
practice! (Just like a musician, eh?) But really... I wonder if NASA trained the astronauts in these many practical uses of the Speedmasters they wore, lo these 50 years ago. I seriously doubt it! I aim to write to Lange to see if someone will reveal (or ... 

That a spring might expend less energy than an end-to-end drive-train is a surmise . . .

 
By: Dr No : July 10th, 2019-08:51
. . . predicated on its capacity to act as a reservoir. A drive-train would necessarily require constant delivery. Perhaps Richard H can be persuaded to comment. Art