Avia Ajustor: The  Best Vintage  Watch You’ve  Never  Heard  Of


For those looking for something a little bit different, we have asked our expert on the weird and wonderful to come up with some off-the-wall suggestions. He kicks off with the aptly-named Avia Ajustor.

Back in 2013, when URWERK unveiled its EMC (Electro Mechanical Control) watch, it was described as: “The world’s first precision mechanical watch in which the timing can be monitored and adjusted by the user, on the fly.” While the URWERK was by far the cleverest example in its class, incorporating a hand-crank-powered optical sensor to read the rate of the watch and display the daily gain or loss to its wearer on a dedicated dial, it was actually not the first. The concept of allowing the owner of a watch to be involved in the regulation of its timekeeping without opening the case has been with us for over 60 years!

The Pioneers

In the early 1950s, Swiss/American brand Croton brought out the Acurator. This watch was marketed as being “waterproof” – a bold claim as, not only did it not have a screw-down crown, it also had a hole in the caseback. The gasket-protected hole was capped with a flat screw head that fastened directly to the regulator on the top of the movement balance. This crude but effective mechanism allowed adjustment of the watch’s rate by moving the screw clockwise or anticlockwise. There was no gearing or capability for fine adjustment and so the chance of getting the watch to keep time and stay true was more down to luck than judgement.

Croton Acurator Medicus field watch (Image: Catawiki)

A screw on the Croton Acurator’s caseback allowed rate adjustment without opening up the watch. (Image: Catawiki)

The year 1957 saw an altogether more sophisticated approach from US brand Benrus. Having overtaken Hamilton to become the third largest American watch brand after Bulova and Elgin, the company was keen to cement its position with innovation. What it came up with was the “Self- Regulating” automatic watch. A long article in the Horological Institute of America Journal in May 1957 explains the workings of the watch. Essentially, any correction of the time by setting the hands would make, via a rack and gear system, a tiny adjustment to the balance regulator. So, if your watch was running slow and you needed to move the hands forward to catch up, the rate of the watch would be slightly increased, and vice versa.

The degree of increase was limited (about 5 seconds per day at each setting), so even if you had to adjust the time by several hours you could not break the system.

Benrus Self- Regulating automatic watch (Image:

Benrus Self- Regulating automatic watch (Image:

After several days of adjustment backwards and forwards, you would eventually “tune in” your watch to the correct rate. Should the watch stop once the rate was set, owners were advised to set the watch to 10 minutes past the correct time, push the crown in, and then set it back to the required time so that the back and forth movements would cancel each other out. Ingenious it may have been, but it was just too time consuming and complex for the owners and the watch was not a great success.

Ajust a Minute

The development of user-adjustable watches went silent for almost a decade but, at the end of the 1960s, Avia came up with a solution that was both simple and elegant. Named the Ajustor (the d is not only silent, but absent), it was based on the FHF73 movement but heavily modified to allow tiny adjustments to the balance regulator via two pushers set into the caseband, marked “+” and “-“. These pushers engaged a series of cams that pushed against a rack of fine teeth that extended from the balance regulator. It was easier to use than the Benrus solution and capable of much finer tuning than the Croton.

Avia Ajustor

Its scarcity today suggests that the watch was no more of a commercial success than its predecessors. Although, in theory, such a watch could be made to run far more accurately than its competitors, the suggestion that the watch might need adjusting was not a good marketing message. Another factor was the price: it was listed at £276 in 1967, which equates to roughly £4,900 today. Finally, there is the question of how many owners could really be bothered to tinker with their watches over the course of a few days to improve the timekeeping. While such activity is popular with watch geeks today, back in the 1960s, a watch was a tool rather than an object of obsession.

Close-up of the Avia’s adjustment mechanism; pressing either pusher engages a sharp point with the fine-tooth rack, shifting its position slightly

From a watchmaker’s point of view, this watch was a problem for two reasons. First, there was the reduction in work as owners took on the job of regulating their own watches. Second, there was the possibility of greater damage to the movement from whatever had caused the poor timekeeping and which the self-adjustment had covered up. The watch might run for longer between services, but this might be at the cost of extra wear to the movement, the symptoms of which were being masked.

On the upside, the Avia Ajustor, while maybe not the watchmakers’ friend, is a rare and quirky example of 1960s ingenuity that would sit well in any watch collection and can be picked up, for the moment at least, for next to nothing.