clock & barometer repairs
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400-day torsion clock repairs

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 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, these torsion clocks can be a problem so I don't like to have more than a couple on the go at any one time. 400 day clocks 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 Anniversary clocks are very well machined, on a par with French carriage clocks. They are precision-made since on one winding, they will run fifty times longer than most clocks, not that the mainspring is fifty times longer but because it's stronger to drive the much higher gearing introduced by an extra wheel and the fact that 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 gradually loses power.

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 excellent 'Horolovar 400 day Clock Repair Guide' - the bible for these torsion timepieces, is full of detailed history and dating information, and illustrates the back plate of many torsion clocks to help determine which of the 24 types of suspension spring they need. It costs about £30 but another excellent book for general repair technique is Joseph Rabushka's 'Repair and Restore your 400 Day Clock' (about £15). You'll find both on Amazon. Another source of information for repairers is Mervyn Passmore's automated Anniversary clock identification system - which is FREE!

Unless there is something special about it, overhaul costs are generally modest but costs will increase if someone else has tinkered with it first because it can take me 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. I've never had to re-bush a single pivot hole in one of these slow-running clocks myself and it's usually pretty easy to spot any tampering of the eccentric screw as it's brass and set tightly in the factory during manufacture so the screwdriver slot gets chewed up easily. It never needs adjusting so any damage quickly confirms the clock was worked on by a novice; in some extreme cases of tampering I will not be able to help.

The suspension spring is the most fragile part and if it's damaged a new one is required (I only use genuine Horolovar suspensions). I also offer a suspension spring identification service if you want to buy a suspension and make up your own but be aware that these springs are delicate and easily buckled while fitting the fork and blocks, and that will almost certainly render it useless. For more on this service 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.

The only other thing that might be required is a new mainspring but it's fairly rare. I don't generally polish up the base and columns but if you like that sort of finish, do it before handing it over to me as these clocks are too delicate to polish afterwards. By the way, if you've cracked or lost the protective dome, visit my page on Glass Domes.

The base of these torsion clocks is only thin spun brass and although most have a wooden insert for added strength, I have seen two examples of the base being damaged in the post, not from external impact but from the sheer weight of the movement on its seat board driving the two pillars into the base if the carton is dropped. So if you're posting it to me, try packing it sideways with plenty of support to reduce the risk; remove the pendulum and pack it separately. And do NOT include the glass dome or the key.

Second, the escapement is finely balanced and it can be knocked out of beat if roughly handled in transit, but the risks are even higher during unpacking and setting up. It doesn't much matter when you're posting it to me for repair but I am not at all keen on posting these clocks back and would prefer personal collection, which usually gives you the reassurance of seeing your clock running first. I will post it back if you insist but you must recognise and accept the risk of having to return it again to be reset once more. I won't charge for resetting (once) but you must bear the cost of postage both ways.

Have a look at Prices next. Most paid for work is guaranteed.

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