WD40 - The watch's enemy.

click on the image for a larger view

Not for the first time I have had a watch in sprayed with WD40, you can't mistake that smell.

The watch has a 15 jewel Ehrhardt movement - probably a 1906 series but I have yet to take the dial off - it was made for the British Military during WWI  (note the broad arrow property mark below the serial number) but was one of many made by the company that were never delivered and then put into silver cases and sold to the public, this one hallmarked by Ehrhardt in 1921.

It was advertised as "in very good condition and working" and "the watch will run the full length of its wind but does run slow I think it needs a service, the watch sum [sic] time stops I shake it and it starts again".

To get it going someone (possibly not the vendor but I would not bet on that) had sprayed it with the dreaded WD40, it may have run for a short time but on arrival only ran with pressure and it is easy to see why when you look at the hairspring, several coils of which are stuck together. And the stuff will have got all over the place causing other problems.

It should be restorable but will take longer than it should.

WD40 is great stuff - but not on watches!

An early Ehrhardt crown set watch based on a Waltham idea.

The watch is by William Ehrhardt for "The London Manufacturing Goldsmiths Co Ltd of Nottingham" and signed by them and dated from the hallmarks to 1895.

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.

Coventry made "Own Label" watches

Rotherham 19J 1903 keyless branded
"Time O Day"
by Russell of Liverpool

After an exchange of Facebook messages and posts with the Coventry Watch Museum I have been doing an analysis of the watches I have handed recently to see how many Coventry watches were signed by a third party. I looked at three of the large Coventry makers - Rotherham, Errington / Williamson and Wm Ehrhardt  who although based in Birmingham is normally considered to be part of the Coventry trade.

The analysis will understate the number signed by third parties because although many are signed on the movement and/or dial many are signed only on the dial and as explained in my blog post "Why the blank faces? some of these will have been done using a fragile transfer print process which over time can be lost.

 This is what I came up with:

	Total #	3rd party signed
Rotherham	70	69%
Errington	44	73%
Ehrhardt	24	63%

I suspect that the Ehrhardt percentage would have been at least as high as the others originally but they produced a cheaper watch which was more likely to have a transfer printed dial signature than a more expensive enamelled version, for this reason and the sheer numbers involved I have excluded from the Errington sample  the Williamson 1905, 1910 and other late model which were widely sold under other names.

It is also revealing that apart from J.W. Benson there are very few "repeaters" in the list with most of the names being small local companies, indicating that, as I expected, relabeling Rotherham and other Coventry made watches was a widespread practice.

Naughty Mr Ehrhardt.

This is a 1910 series by Wm Ehrhardt branded "The British Watch Co" one of their trading names after 1921. They come up very infrequently and this was the first one that required some work on the winding and setting mechanism and what did I find?

Ehrhardt. had ripped off the design of the shifting sleeve setting mechanism from the Waltham 1899/1908 models. They are in fact identical and to fix this watch I used a small piece part from a Waltham.

Not that it did them much good as they stopped manufacturing not long after this example was made whilst Waltham continued making pocket watches until just after WWII and wrist watches until 1957.

An "In Beat" Design by W. Ehrhardt.

W. Ehrhardt Full Plate Keyless. 1920

At first glance this is a fairly standard full plate keyless watch, albeit a very late one from 1920. However things  are rather different under the covers, instead of a normal balance cock this design has the balance cock mounted on a ring that fits into the top plate of the watch.

This design makes the watch rather more robust, slightly slimmer (although it is still considerably thicker than a three quarter plate) and makes it very easy to get the watch "in beat".

Being in beat means that the balance action is symmetrical swinging an equal distance in each direction and that the balance staff, impulse jewel and pallet arbour are in perfect alignment. If you think in terms of a long case clock the "tick" equals the "tock" and it has a steady rhythm.

This can normally be a tricky operation involving quite a lot of work and often much fiddling with the hairspring which always has some risk attached to it. With this design the impulse jewel can be lined up simply by rotating the balance cock to the correct position and locked there with the two screws that hold it to the movement.



Three views of the movement, left before fitting the balance cock, the lever pallet can just be seen in the "well" where the balance fits, centre is the balance cock and regulator in place and right with the balance assembly in place (click on the image for a larger view).

After initial adjustment this example was within beat to 0.14%,  better than my  modern Rolex which is still excellent at 0.45%.

Unfortunately it did little for Ehrhardt who was out of business shortly after, or for watch design as the full plate movement was already obsolete by the time this was made, replaced by the three-quarter and split plate movements.