Montblanc

Ornatus-Mundi
[Zenith]
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In case I am right your picture shows it well...

I am talking about the shape and the geometry of the chronograph teeth.

Minerva sought to improve the measurement of time by optimising the interaction of the transfer wheel (which is mounted in the axis of the seconds wheel and engages, once the Chronograph is switched on, with the intermediate wheel to transfer the energy to the Chronograph seconds counter) with the intermediate wheel.

This is achieved by altering the shape of the teeth on the transfer wheel to a more rounded, nearly epicycloidal shape of the teeth (lower part of the image below). This allows for a maximun of depth of engagement between the two wheels while minimising friction, resulting in an increased regularity and consistency of interaction. Your picture is shows how deep the wheels interact. Imagine the friction that could occur if wheel engage that deep!



It seems to bring real benefits: According to Demetrio Cabiddu, the amplitude of the balance stays constant at nearly the same rate with or without the Chronograph being engaged, a testimony to a Chronograph mechanism which requires less energy. To cite him: "This new shape may be less traditional or optically not completely in the spirit that we are striving for, but it is technically more advanced and more functional".




This type of teeth are found on the transfer-wheel of the Cal. 13-21 and Cal. 16-29.

Best,
Magnus
This message has been edited by Magnus Bosse on 2009-04-28 08:05:46