How much torque does an average mainspring produce at the barrel teeth?
Here's a short list:
- 7001 and 2892-A2 slightly less than 8 Nmm;
- 7750 around 9 Nmm;
- 2824-2 around 12 Nmm;
- 6497-2 above 20 Nmm.
All Nivarox mainsprings, moments measured in Nmm (Newton x millimeters) at full charge, below gliding limit for automatics.
Source: ETA data sheets.
And if you really want to delve into mainsprings, I have found very interesting information in:
Kelly - A Practical Course in Horology (1944)
Kleinlein - Adjusting Watches (1920)
Britten's Watch and Clock Makers Handbook (16th ed. by Richard Good, 1978)
Rawlings (et al.) - The Science of Clocks and Watches (3rd ed., 1993)
Swinburne - The mechanism of the watch (1950)
Van Den Broek - Elastic Energy Theory (2nd ed., 1942)
The first two books are easily found in pdf.
Don't skip over the edition of the books listed. It makes a lot of a difference.
Also, can anyone point me to a more in depth study of watch movements? I'm interested in the math and various engineering aspects like power consumption, efficiency, geometry of teeth, escape wheel and pallets...
The late George Daniel's "Watchmaking" suggested by dom_ is a fantastic mix of practice and theory for everything related to the making of a watch. Rawlings' "Science" (op. cit.) is more on the theory side, and definitely worth having too.
Leopold Defossez' "Théorie Générale de l'Horlogerie" (1950) is a great reference book for those with a robust math background. Another excellent Swiss textbook is "Théorie de la construction horlogère pour ingénieurs" by Vermot, Bovay and Falco (2006) edited by Laboratoire Horloger (LaHor) de la Haute Ecole Arc Ingénierie. More on the Swiss side, Hans Jendritzki wrote several practical books interspersed with very clearly exposed theory.
Some of the above mentioned books may be expensive, but there are lots of excellent horology books available for free on the internet. In all probability you will love a visit to gutenberg.org or the archive.org, even just to read Kelly's Course.
// ocram
