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Stories of reconstruction, revival and renewal


The story

In this case study, we are examining a high-quality perpetual calendar mechanism. This is a unique mechanism - because once it is set, you don’t have to alter the date for 100 years! The mechanism we’re looking at here was in a watch that needed a good cleaning and overhauling to ensure that it ran properly once more – so this presented an excellent opportunity to share with you what goes on inside a watch with this kind of complex and sophisticated mechanism.

This is the date wheel with 31 teeth - and with a steel cam screwed to the wheel. The cam allows the operating lever to drop early and advance the wheel 1,2,3 or 4 teeth, depending on whether it is a shorter month than 31 days , i.e. 30, 29 or 28 days.

This wheel has seven teeth and represents day of the week.

This intermediate wheel also has 31 teeth and connects the date wheel and perpetual wheel. One tooth that is longer than the rest and only comes into contact on the 31st day of the month. This will advance the perpetual wheel one month.

The moon phase has 59 teeth and will revolve once every two months (this is why there are two moons). The dial this is made of gold and is enamelled. The cycle of the moon is 29 and a half days – though it is not possible to make half a tooth. After three months the phase would be out by one-and a-half teeth and would need to be continuously adjusted.

This is an operating lever, and has four functions.

The top claw shape changes the day wheel, whilst the middle claw drops into the perpetual wheel, which rotates close to this claw. The bottom two claws advance the month, whilst the longer of the levers will sit on the month wheel cam and drop early – and if the month is short, this will advance the wheel. The bottom claw will advance the month wheel on the 31st day only.

This is the perpetual wheel with 48 teeth and 48 divisions screwed on top. This rotates once every four years – and  the area circled is for the month of February. There are also three other cut outs at the same depth; the division at the 1 o’clock position is slightly shorter, since it is the 29 days and leap year indicator. Usually, on the dial, there is a  leap year indication - otherwise the calendar would need to be set to every February until the leap year is found. Then, to set the calendar correctly, it would be set from the previous leap year.


In this time-lapse video, you can see described levers in position and on the lift. It took six hours to complete a leap year cycle, so to save time we used the 30th day of the month. The operating lever with longer finger piece (or claw) has dropped early into the date wheel cam (see first image).

This has already advanced a tooth, and you can now watch as it slowly changes all the wheels - apart from moon phase, which usually takes place at midday. With all these watches, you will find correctors, which allow the user to advance the calendar; however breakages can happen if this is adjusted on change-over.

Restoration case studies





What our customers had to say

"My great grand-father's Breguet was given to me by my father for my 21st birthday. 30 years later, post restoration by SHWR, it is in far better shape than I have ever seen it. SHWR's craftsmanship is immaculate. The firm is polite, professional and honest. Outstanding - I cannot recall another occasion when I have been so favourably impressed."


What our customers had to say

"I have just had my 1934 Rolex Oyster repaired. From start to finish I had full confidence in every one I had contact with at Steven Hale. They have been very efficient in identifying the problems at the initial examination and dealing with them as promised. There were no nasty surprises and unexpected complications along the way. Because of the age of my watch, spares are not available, and new parts have had to be made - all very expertly done. They even polished the gold case and my 86yr old watch now looks as good as new. You can certainly trust these people with your precious timepieces."


What our customers had to say

"Fantastic job repairing a family heirloom pocket watch which will now return home to Namibia.
The service was superb with detailed repair and service quote. Communication throughout was equally great leaving you with the confidence that you watch is in the best possible hands."


What our customers had to say

"I had bought a 1970s Pepsi GMT at auction and it needed some work. The lume on the hands was breaking up. Rolex UK wanted some hilarious price and threatened to replace the hands with new ones if their work failed - all at my expense of course. Steven Hale and co managed to repair the hands and maintain the original patina of the 40 plus year old watch which was of course crucial! Highly recommended."


What our customers had to say

"These are watch lovers and it shows. Their meticulous craftsmanship and expertise make them unique in London and I suspect that only in Switzerland may their equivalents be found. The experience of Steven Hale Watch Restoration begins with the talented and charming individuals who are client facing in South Molton Street and who instil a confidence that is consequently fully fulfilled. This firm represents unequalled talent in its field as well as exceptional client service. I have seldom recommended anyone with greater conviction."