Thursday, 6 November 2014
An early Ehrhardt crown set watch based on a Waltham idea.
It is an early (for an English Watch) crown negative, pull to set, movement when most English keyless watches were pin set.
It is laid out as an English Lever with a Swiss style club tooth escape wheel and lever, again this was an early adoption by Ehrhardt as a half way house to the full Swiss Lever.
The crown setting arrangement is most unusual with a conical shaped piece on the winding stem engaging with a fork shaped lever (just visible in the picture to the right) which hinges as the stem is pulled rather than slides. This has then to be converted into a double action.
The winding gear cog is pushed through the face plate to engage the main winding gear (top centre in the lower picture) and the motion works - below it in the picture..
The rocking arm which runs from the main winding gear to the left has also to be lifted so that the intermediate gear is disengaged from the gear attached to the mainspring (left).
A most complicated way of doing things and as far as I can see a poor adaptation of the idea behind the mechanism seen in Waltham 1877/83 model key and lever setting mechanisms.
This was not the last time Ehrhardt were to take a Waltham idea for crown setting, but on their 1910 series split plate watch they did not bother changing the shifting sleeve arrangement from the 1899 model Waltham, they just made a straight copy.