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Hermle (pronounced "Herm-lee") was founded by Franz Hermle in Württemberg in Germany in 1922 but most of the equipment was dismantled during post-war occupation, only to be resurected in the 1950s. In 1977 his sons oversaw expansion into the US market with a new subsidiary and the constuction of a bigger plant in Amhurst, Virginia (Hermle Black Forest Clocks). The firm became the biggest maker of clock movements in the world but in recent years the business has suffered several financial setbacks; the number of lines has been reduced and more is manufactured in the Far East these days where cheap labour is plentiful.

Many of their clock movements have rows and columns of light counterpunch marks on the brass plates. Most have the name Hermle on them but on earlier examples you'll see the initials FHS (for Franz Hermle and Son) and others may bear the retailer's engraved names (URGOS, Howard Miller etc) instead.

The three most common spring-driven movements with Westminster quarter-chiming are the 340 series, which has a floating balance suitable for medium-size mantel clocks (see Image 1), and the 341 series (Image 2), which has a pendulum hanger (Image 3) suitable for wall clocks.They also produce a range of weight-driven movements (Image 4) for longcase clocks. Small striking clocks often have a 130 Series movement with circular plates and floating balance (Image 5).

Dating Hermle movements is easy if you look closely at the back plate . Up until 1987, they simply added the last two numbers of the year of make - so 77 indicates 1977. But rumour has it that retailers complained about the system because their customers could quickly spot old stock lines. So in 1988 Hermle adopted a letter code starting with A (see the table below right), so the letter 'O' denotes 2002, and so on, restarting in 2014 with AA. It's not infallible however; in 2012, I bought a new movement with the date letter denoting 2001 so I suspect Hermle were clearing old stock. Nothing wrong with that if they're unused; pre-2010 movements might even be better than current Chinese versions.

Being cost-conscious, Hermle's brass plates are thinner than those found in many older clocks and this leads to pivot holes wearing more quickly, so it's especially important to give these clocks an oil service every three years (£40). If you don't, worn pivot holes can be re-bushed but in some movements the pivot holes are so close to the edge of the plates that re-bushing is not safe. Also, Hermle mainsprings seem to be less durable so a frequent complaint is that after ten years, a Hermle clock will only run for four of five days instead of the usual eight, and that the strike and chime sound sluggish after a few days from winding or stop altogether.

Fortunately, because of the efficiencies of large scale Chinese production, it can cost less to fit a new Hermle movement than to overhaul an existing one, especially if the mainsprings need changing. The springs themselves add around £35 each to the cost of a service (£200). So the cost of overhauling your existing one could be over £300 whereas a new three train movement might typically cost £275 to supply and fit - it depends on the model. Small striking mantel clocks are also cheaper to replace, typically £200 (as opposed to £220 for overhaul and two new mainsprings). The existing dial, hands and gongs are all re-used so the clock still looks and sounds the same. And of course it's quicker so you can have your clock back in a week or less.

If these costs exceed what you can afford, there is a cheaper alternative, which is to remove, soak, wash, rinse and dry the movement without first dismantling it. You cannot immerse the mainsprings in the cleaning solution because they will oxidise (rust) and the clock will quickly stop. But like many German movements, the Hermle design allows the mainspring barrels to be removed without separating the clock plates. This is helpful because stripping and rebuilding a clock is time-consuming and therefore expensive, so it can be avoided. At just £100, it all adds up to much less than a fully stripped service, though there is no guarantee because even in an ultrasonic tank with the best cleaning fluids, a fully assembled clean cannot remove every trace of dirt. More importantly, it won't help if the mainsprings are tired ("set") or if any pivot holes are worn because re-bushing requires dismantling.

In case you're wondering, a three train version is more expensive than a two train even for a fully assembled clean because the underslung chime assembly has to be removed to get the Going barrel out and that means you're faced with the setting up of the chime sequence after you put it back again.

Incidentally, for any repairers reading this, I've found that the simplest way to reset the chime on the underslung unit is first to prise off the circlip holding the lower of the two four-spoke wheels of the chiming train on the outside of the backplate (see third photo opposite); then slide the wheel off a little so that it disengages from the two smaller wheels above and below it. Next, turn the loose bottom wheel until you see a run of four hammer movements in sequential order (1, 2, 3, 4) and stop - the chime train has now run the 'quarter past' position. Now run the going train by turning the centre arbor until it strikes the hour (any hour), and then rotate it through another another 90 degrees until one more chime activation, and stop. Finally, without moving either of the two smaller wheels, refit the four-spoke wheel to re-engage the chiming train again and refit its circlip.

Overall, Hermle movements aren't the easiest to work on but given the price they are decently made and will last 25/30 years if checked and oiled periodically. If you don't maintain them, however, you will probably have to replace them after 15 years.

For more, check out the Hermle website.

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2 and 3 train movements

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Dating your Hermle clock

On the brass backplate of your Hermle clock movement you will find either two numbers (pre-1988) or a capital letter (post 1988) which denote the year of make: