clock & barometer repairs
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400-day torsion clocks

After reducing the number of hours I can devote to this hobby, I'm afraid I no longer take repair enquiries for these clocks, but here's a bit about them.

The humble 400 day clock is also known as an Anniversary clock (as it's supposed to run for a year on one winding), or a Torsion clock (a term I prefer but which is not widely recognised outside clock making circles) but all three terms are interchangeable. An advantage to the collector is that 400 day clocks are largely unloved and under-rated and often, therefore, ridiculously cheap, but there is a reason for this.

The majority of repairers avoid them because it's not economic and they need additional effort and focus. Also, the pallet depth is different and setting them in beat can be a challenge. Testing also takes longer and so they can be labour-intensive to set up. Even when you know what you're doing, torsion clocks can be tricky. They also have a reputation for poor time-keeping but that's partly because they are left uncorrected for weeks as they don't need frequent winds, so it's often just a gradual accumulation of a lost half-minute each day.

Almost exclusively German in origin, a great many torsion clocks are very well machined, on a par with French clocks, which is uncommon in many German clocks. They are precision-made since on one winding, they will run fifty times longer than most clocks. That's not that the mainspring is fifty times longer; if anything it's shorter but it's much stronger to drive the higher gearing introduced by an extra wheel and a single swing of the pendulum typically takes seven and a half seconds instead of a fraction of a second in many other mantel clocks. Having said that, unless you rewind them two or three times a year you might find them losing time after six months as the mainspring power gradually reduces.

Some of the prominent Torsion clock makers include Gustav Becker (Image 1), Jahresuhrenfabrik ("JUF" - who coined the 'Anniversary' name and also produced a larger "bandstand " version as in Image 2), Kienzle, Kieninger & Obergfell (KundO), Badische Uhrenfabrik (Image 3) and Phillip Haas. The French firm Claude Grivolas also made 400 day clocks mostly with integral case rather than under a glass dome. Uniquely, these Grivolas clocks are front wound and Images 4 & 5 show the front and back of the movement. But there are many more including the collectible (and overpriced) Universe clock from Kaiser. The pendulum of most Gustav Becker 400-day clocks takes the form of a heavy, lipped disc with two small weights on top that can be adjusted in or out to regulate rotation speeds. Other makers also use a plainer disc but the four rotating balls type pendulum is the most common.

The 'Horolovar 400 day Clock Repair Guide' is the bible for these torsion timepieces, with a whole section on the 24 strengths of suspensions available but for general maintenancevJoseph Rabushka's 'Repair and Restore your 400 Day Clock' is very good. You'll find both on Amazon. Another source of information for repairers is Mervyn Passmore's automated Anniversary clock identification system - which is FREE!

If you find a repairer willing to take one on overhaul costs are generally modest but costs will increase if someone else has tinkered with it first because it can take twice as long to correct their mistakes, especially if they have re-bushed any pivot holes, moved the pallets or worst of all turned the eccentric screw that supports the escapement arbor.

The suspension spring is the most fragile part and if it's damaged a new one is required, use genuine Horolovar suspension material. For more on this check out my short guide on How to make up a suspension. Also, you'll need to know how to set the clock in beat after fitting it yourself.

By the way, if you've cracked or lost the protective dome, I can't help; for reasons I've not been able to fathom, every size of dome is available except the size most commonly used. See my page on Glass Domes.

If you're looking for information on a more sophisticated type of torsion clock, visit my page on Jaeger LeCoultre ATMOS clocks.



  • A typical antique torsion clock by Gustav Becker, Germany, with standard galleried cast brass disc pendulum and silvered dial c.1910
  • A huge 400 day 6 pillar 'bandstand' clock by Jahresuhrenfabrik (JUF) with the ubiquitous four balls pendulum c.1905
  • A rarer anniversary clock with disc pendulum by Phillip Haas of Germany c.1910 before restoration
  • The front-winding dial of a French 400 day clock by Claude Grivolas
  • The signed back of the same French 400 day clock by Claude Grivolas