I was able to buy this nice cockpit instrument for a good price (175 US$). It has only one small defect: the lower left screw hole is a little damaged.
For the rest is very good and keeps good time!
Is there anybody who could help me to understand how is it rare and what aircrafts did mount it?

Hi Claudio.

These are relatively common and were developed from the Type A-13 that came out in the early 1950s. They come in several variations and were manufactured and purchased by the different parts of the U.S. military in large quantities up until the 1990s.

There is no way to tell what aircraft yours came from since they were used in most every type of aircraft including both fixed wing and helicopters. The US military kept them serviced so whenever one would break it would be replaced by either a new one or a repaired one. One clock might have been installed on several different aircraft during its lifetime with the Air Force, or Army or Navy.

The price you paid was okay, but you can often find them for a little less on Ebay. They are considered to be chronometers, but I do not see them as having been made to quite the same quality standards as older chronometers. They were designed and used as the regular aircraft instrument panel clock at the begining, and by the end they were the mechanical backup clock to electronic clocks. As such, I do not think they are likely to reach the high values that old ship chronometers or the World War II era aircraft chronometers have. Still, I think they are nice aircraft clocks and every collection should have a couple of them.

Warm regards,
Jim

Thanks, Jim!
sorry there was no way to enclose the image... Now finally I have had success!
I've a doubt: this ABU A-1 is very different by the Type A-13 and it seems derivated by the Jaeger Chronoflite A-10. Sorry: it's my fault. Did we speak about the same clock or did I make you wrong? In this case, please, forgive me.

The movement seems to be the same evergreen Jaeger that we can find in many many cockpit clocks, but it has two different, unusual, features:
1) when you pull out the left knob to set the time, the seconds hand zeroes (hack set)
2) the seconds hand is for continue seconds and not for the chronographic function.

Hello Claudio,

My "USAF ABU-3/A 8 DAYS" looks to be an almost twin to your example. The type fonts on mine are little thinner and more condensed. Also, my "PUSH HARD" button says only "PUSH".

My example was purchased from the retired USAF pilot who flew with the timepiece in a Convair B-58 "Hustler". The pilot even included a photocopy from his B-58 flight manual that described the function of this instrument.

Regards,
Ron

Wow! Interesting!
Are the functions of the seconds hand the same? (hack set and continue seconds hand?).
May you post any images?
thanks!

Hello,

Pictured with the appropriate page copied from his B-58 flight manual, this is the ABU-3/A purchased from the retired USAF B-58 pilot.
-The seconds hand is reset to top when the "WIND" button is pulled out. It resumes when pushed back in.
-The appearance of your clock follows more closely the B-58 flight manual. For example, my dot is white/black (not white/red), and my "PUSH" button is the manual's "PUSH HARD" button.

Ron

The B-58 pilot's station.
-The clock is installed near the pilot's left knee.

Wow! First of all, thank you, for sharing, dear friend!
What a wonderful clock! And very interesting scans!

The manual well describes the features of the clock, comprise the unusual functions of the central sweep seconds hand.

The yours seems to be a nice Le Coultre: fine Swiss maker, maybe made or assembled in the USA factory.
The mine is a Wakmann (Breitling), marked as made by WAKMANN WATCH COMPANY INC. NYC US.
The airplane and its cockpit are simply amazing! And this makes your clock very, very interesting!
I've looked for an image of the cockpit on the Internet, but none shows the clock very well. Your scan is great!
Thanks and thanks again!