WW2 Japanese clock for the instrument panel seiko

[mjacobs784]

Has anyone seen a similar aircraft clock with the dial with the "12" at the bottom? Most photos I've seen show it both ways; the "12" at the top, the "12" at the bottom. Was this common for the Japanese pilots who wore it both ways from a parachute cord around their necks? Also, is this an Army or Navy clock? Any help would be appreciated.

[Nick Komiya]

That is a Type 100 Army flight clock made by Seiko, adopted in 1940 (previous model was called the Type 93), which was adapted from the model 19 railroad clock. This clock was available in 3 forms, as an instrument panel clock like yours, a pocket watch model or as a wrist watch, all having the same mechanicals and face.

The correct spec for the Type 100 instrument panel model housing was to have the winding crown at 6 o'clock, but yours may have been a conversion from the pocket watch version, which had the crown at top, as shown in the photo below. WW2 German BO-UK1 flight clocks, which I am familiar with, would have had the function of resetting the second hand to 12 when you depressed the winding crown or a separate reset tab. So with that sort of mechanism, you could not simply mount things upside down, but I don't know how the second hand worked on a Type 100, so it may even be that it was simply reassembled upside down.


For ease of synchronizing with other crew and to protect the clock from damaging vibrations, pilots tended to wear the clock hung from a cord threaded through the screw holes more often as the war intensified. But in that case, some wore it 12 down and others the other way around.

[mjacobs784]

Thanks Nick for your expert advice. If you come across any further evidence in regards to my clock with the winding crown at 12-o'clock position, please feel free to contact me.

[RussM]

Although this doesn't appear to be quite the same instrument, it does show the winder at the 12-o'clock position.

Regards

Russ

[Nick Komiya]

What Russ shows is the navy's version, which was designed that way to have the winding crown at the top, reverse of the army configuration.

Although the mechanicals of the navy model was also the Model 19 Seiko, the disengaging mechanism for freeing the arms to be reset by turning the crown was totally different between army and navy models.

The navy model had a slide at 10 o'clock to free the arms, while the army model did that by just pulling the crown towards you and then turning to set the arms. In this case, the navy system was the older system similar to the 1939 Luftwaffe setup (with disengagement lever at 3 o'clock), whereas the army system was more advanced and worked the same way as the post-1940 Luftwaffe clocks.

[Nick Komiya]

After reading several Japanese sites, I am now quite certain that the wrong knob position for the army clock is due to a postwar rebuild and not its original war time configuration. Reversed knob positions are obviously observed elsewhere too, as one site points out clearly that those variants are products of post war tampering that did not exist in war time.

[mjacobs784]

I guess Nick that says this clock was rebuilt. Now the big question I have, do you think a watchmaker can rebuild this clock to its original position with the knob at the 6 o'clock position? Any thoughts if this is possible?

[Nick Komiya]

Your town watchmaker should be able to tell you that at no charge, just by opening the back.

[mjacobs784]

Thanks Nick. I'll start checking it out with a watchmaker.

[mjacobs784]

Hello Nick. A Japanese collector Junichi Kamura sent me this photo of his clock similar to mine taken off a damaged Japanese WWII aircraft in 1944 with the missing knob at the 12 o'clock position. Might this change your opinion if you still feel that my clock was a post war rebuilt. I did find a watchmaker that could convert my clock, but I'd like your opinion first after seeing this photo.