Movement Stories: Elgin 626
The Elgin 626 is a neat little USA-made movement from the late 1940s designed specifically to power the sub-second tank-style watches popular at the time. As such, it departs from the typical round movement configuration and is arranged in an oblong lozenge shape. It is nicely made & finished and has 21 jewels, a high jewel count for a movement with no complications. However, the horologist who designed this movement clearly must have been a bit bored with the lack of complications, because they seemingly went out of their way to add some truly strange design features. We will explore these oddities below.
View of the Elgin 626 watchmaker side
The first quirk of the 626 design is in the cap jewel settings. Compared to more ultilitarian 17-jewel examples from the same movement family, the 626 gets its extra jewel count from prolific use of cap jewels. The escape wheel is capped on both sides of the movement, while the 3rd and 4th wheels are also both capped on the watchmaker side. The cap settings on the watchmaker side are odd in that they are attached by screws from the bottom of the train wheel bridge. It’s not clear why this was done, other than creating a cleaner look for the movement. It has some (IMO) unfortunate side effects, notably that the cap jewels need to be lubricated and installed before installing the bridge. This is a fiddly operation, since the bridge needs to be flipped over to install the screws while the caps are held in place, either by oil surface tension or, barring that, a bit of rodico. It also makes it slighly more difficult to install the bridge properly because the caps somewhat obscure your view of the train wheel pivots. All in all, it seems like a lot of trouble to improve the aesthetics of part hardly anyone will ever see.
The next quirk of the 626 design, and fortunately a relatively innocuous one, it the design of the click mechamism. The large click spring actually wraps around the mainspring arbor setting. In addition, the way the spring engages with the click is different from the typical practice in Swiss watches, which usually have a post extending downward from the bottom of the click that engages with the spring. Instead, in the 626, the click itself is extra-thick, and the spring engages directly with the side of the click tooth. The click spring is also blued, with is kind of cool.
Closeup of the 626 click mechanism
Naturally, I saved the best, or worst, for last. The last, and perhaps greatest, quirk in this movement design lies in the keyless works. At first glance, the design seems pretty conventional, similar to typical Swiss keyless works designs using a sliding clutch, setting lever, and yoke. The surprise doesn’t come until you disassemble the mechanism. In virtually every design of this type, the yoke rotates around a post that is milled in the main plate of the movement. However, in this case, for some reason that I can’t even pretend to understand, the post that holds the yoke instead extends from the bottom of the setting lever spring.
Closeup of the setting lever spring, showing the post that holds the yoke for the sliding clutch
The post on setting lever spring passes through the yoke, then seats in a corresponding hold drilled into the main plate. The problem with this design comes when reisntalling the yoke. Because there is no post on the main plate to hold the yoke in place, it tends to sit somewhat precariously, at a slighly cockeyed angle, when inserted between the setting lever and the yoke spring. To complete installation, the setting lever spring needs to be placed so that the post on the underside sits in the yoke pivot hole. Then, the setting lever spring and yoke need to be pulled (carefully) sideways against the pressure of the yoke spring while pressing down sligtly until the post seats in the hole in the main plate. This isn’t too difficult to do, but it seems like a lot of trouble given that this odd design provides no clear functional advantages compared to the more conventional approach. Perhaps doing it this way made the main plate easier to mill, but this would seem to be more-than-countered by the additional complexity of having a post as part of the setting lever spring. It also means that the post (along with the setting lever spring) can be replaced, but I’ve never seen a movement, including much older examples. that has a wear issue with the yoke post. In any event, the thinking behind this design remains a mystery to me. Add a comment if you have an idea why it was done this way!
When I initially finished reassembling this movement it ran (as you can see in the top photo), but unfortunately it did not meet the minimum performance standards I set before selling a vintage watch as properly restored. This is due to issues with the balance. When I received the watch the balance had been installed incorrectly, and the hairspring was interfering with the center wheel. This seems to have distorted the hairspring in a way that ruins the performance of the watch and that I am unable to correct with my modest hairspring manipulation skills.
I have ordered a brand new balance for this movement, and I will post an update when I receive and install it. Hopefully it will fix the performance issues and I can get this movment back into the handsome Lord Elgin watch that it came from.