WWII 8 Day A-11 Cockpit Clock

Usually the watches I work on are too small to be able to clearly photograph a restore in a way that actually shows the problems and the work rather than what appears to be some arbitrary pictures of a watch taken apart and put back together. Fortunately this 8 Day Bulova Aircraft 21AE movement was monstrous enough to be able to show the full process and the problems along the way. The picture quality is much lower than typical posts, but that is because I used my camera phone to avoid constantly having to set up light box and use the professional camera.

Before I walk through the restore, Here is a brief background on the significance of this clock:

There were three makers of these particular 8 day clocks: Elgin, Waltham, and Bulova. Far and away the rarest to find are the Bulova ones. I am not sure why this is but observation has shown that they pop up less frequently than the other two. These 12 hour clocks were used in the cockpits of B-17s and B-29s during WWII. Named the A-11 they matched the name of the accompanying wrist watches also used by pilots of the time.

Now on to this clock:

Not only had this clock been through WWII, but also perhaps worse, someone clearly unqualified to service it tried nonetheless. Now I do not consider myself an expert nor do I believe I possess any special skill in the realm of watchmaking (other than a love and respect for the craft), but opening this movement up made me realize that I am at least better than some.

Taking this piece apart it became quickly apparent that this was going to be a dirty movement as the close ups show. The oil had crusted up with some dirt to form a gear-stopping grime wherever it had been applied. Over time dirt and lint had made their way in and caked on to whatever parts they could.

To put the size of this movement in perspective, the first photo is the mainspring barrel of the 21AE (left) next to the barrel of an average wrist watch. This is truly a hybrid between a watch and a clock movement and provides a great format for walking through a restore.

21AE mainspring barrel    21AE Disassembly  21AE zoom 21AE disassembly zoom  21AE filthy escarpement

After giving this entire movement a thorough trip through the ultrasonic cleaner I began the part observation. This is where things got really messy (and annoying.)

21AE Parts Tray

The wheel train bridge (the part that reads Bulova Watch Co.) that holds the escape wheel (the odd looking little wheel in the fifth picture) and the fourth wheel (the normal looking one next to it) had been put on with so much force and with the fourth wheel so far out of alignment that not only had the fourth wheel pivot been badly damaged, but the train itself had been irreversibly damaged. The damage caused the fourth wheel to cock to the side and halt the movement. This unfortunately required the purchase of a new “harvester movement” for the wheel and the train bridge. As the 21AE hasn’t been made for years, I was incredibly lucky to find one.

21AE Main Plate 21AE reassembly 1 21AE reassembly 2 21AE reassembly 3

Finally with the new parts I was able to finish the reassembly and place the balance complete in for that magical moment when the whole thing comes to life.

After finishing up the reassembly, the movement looked much nicer and cleaner and was ready to be reinstalled:

21AE assembled

Finally, once regulated, I fit the dial and hands, and fixed it into its case and for the first time since it arrived it looked and functioned like the amazing piece of military history that it is.

21AE complete

5 comments on “WWII 8 Day A-11 Cockpit Clock

  1. Nab.P says:

    I have a same kind of Clock that reads ” Order No. W535-AC-31412 , MFR’S PART NO. 21AE , . . . . . . BULOVA WATCH CO. ” …. in the panel in its back . . . .the clock is not working . . . . is it like the same you have restored ? . . . can you tell me in what price does this items sell to nowadays in this condition only ???

    • Mark hewitt says:

      I also have a bulova 8day clock serial number af-42-37654-a. Ord num w535-ac-31412 that is complete intact an works. Great i also would like to sell it an am wondering what the value is?

  2. Marvin D. Midkiff says:

    I have a 21ae wwll bomber clock. It belonged to my wife’s late uncle who was an army air corps soldier. It works and looks almost new. Aunt passed away and we got it at the estate liquidation sale.

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