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.
The Anniversay clock is much maligned and many repairers avoid them because they do not fully understand the science and mechanics of these clocks, and struggle to set them up. Unless you really know what you're doing, these torsion clocks can be a problem but not if you treat them with some respect. 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.
Mainly German in origin, a great many Anniversary clocks are very well machined, on a par with French carriage clocks. Well, they'd have to be precision-made since on one winding, they will run fifty times longer than most clocks. This is not because the mainspring is fifty times longer! It's because it's stronger to drive the 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.
Once you acquire one of these Anniversary clocks, you'll want more and as other antique clocks can be prohibitively expensive, these are likely to be a great long term investment. You should buy the excellent 'Horolovar 400 day Clock Repair Guide' - the bible for these torsion timepieces, which 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 - and it's FREE!
Unless there is something special about it, my flat rate for servicing one of the German anniversary clocks is £125 but if someone else has tinkered with it first that might increase because it can take me twice as long to correct someone else's 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 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 is brass and set tightly in the factory during manufacture so the screwdriver slot gets chewed up easily. It never needs adjusting so 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 - £40 fitted plus £5 each if it needs a top/bottom block or a fork). If you just need a bare spring to make up a new suspension yourself, CLICK HERE. Do bear in mind that it's exceedingly delicate and easily buckled while fitting the top and bottom blocks and fork, which will almost certainly render it useless. 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 (£35) but it's fairly rare. If you'd like the movement and base etc polished add £100. I don't lacquer it afterwards but I will wax it to protect the finish. All fully paid for work is guaranteed for 12 months.
A few words on POSTING: 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. By the way, if you're looking for a replacement glass dome, CLICK HERE.
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 also 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.
All paid for work's guaranteed for a year.
If you're looking for more information on ATMOS torsion clocks, click HERE.
400 DAY CLOCKS: