Have you ever heard the expression 'The dirt was holding it together'?
Well, turns out that is almost true in some cases, particularly with clocks.
I run into this quite a lot, a clock hasn't been serviced in many years (99.99% of the time) and sometimes it runs ok, sometimes not. Sometimes it runs quite well, and here I encounter the 'Don't fix it if it ain't broke' kind of thinking. I assure you, this does not apply to a lot of mechanical things, it is better to be proactive and do preventative maintenance.
Clocks are a collection of geared wheels that are basically transmissions. The power from the weight or mainspring is transmitted to the regulating organ, the escapement. In clocks, this can be ancre type escapements like recoil or Graham dead-beat; (There is a dizzying array of clock escapements, some are outright bizarre) but also platform escapements that can be like what you find in watches- a balance wheel with a lever or cylindre escapement (on older clocks).
The former utilize a pendulum that swings in an arc and is mathematically matched to the gear train to give the correct frequency. If you've ever watched a long case clock pendulum of a meter or so, you might have noticed how slow it is, compared to a small table clock, with a much shorter pendulum, say less than 13 cm.
The gears have pivots on each end of the arbors which pass through the usually brass plates. When no service is done, the oil dries out and dirt accumulates on the movt. Clocks are notoriously non dustproof, and this dust will collect right were you don't want it. ESPECIALLY where there is oil or dried oil residue. If the movt has been soaked down with oil, the dirt collects everywhere and acts as an abrasive, destroying teeth, pinion leaves, levers, plates, anything that touches or slips during the running of the clock.
This is why you cannot oil a dirty clock. It mixes with the dirt that is already there and this sludge pools in the oil sinks of the pivots. Additional dust then adds to this. In order to clean this out, you have to fully disassemble the movt, and by doing this, you are well into overhaul territory. This is where the clockmaker encounters wear and tear, and while the clock is apart is the best time to address this, obviously.
After many years (some clocks will run for 50 years unchecked) the residue of dried up grease and oil and dirt can harden into something that looks and acts almost like stone. I kid you not. I have chipped this away from plates many times.
Corrosion also occurs, depending on the atmosphere around the clock, smoke being the number one destroyer of mechanisms. (Clocks from places where smoking was excessive are almost always wrecked) Excessive humidity is also bad, and there was an old myth about putting a jar of kerosene or something in the bottom of a long clock case to supposedly mitigate this.
Do not do this.
The vapour does indeed get around, and it sticks to the mechanism, and will form a sticky film.
Oil or sticky films with dirt on the teeth of brass wheels will destroy them quickly, so you do not want this. Oil belongs in oil sinks, period. And sparingly at that. (the little dish shaped indentations around the pivot holes in the plate)
When a clock gets dirty and is run for many years, say decades, the dirt and corrosion and oxidization and dried up oil residue will begin to limit what is called the endshake of the wheels. Normally the wheels are free to move slightly laterally as well as turn on their axes. Endshake is absolutely critical, but you don't want too much or too little. Too little and the train is really tight and friction will overcome the force trying to run the clock. Too much and the movement is sloppy, and in wristwatches and pocket watches, endshake is finely adjusted in chronometers to make for a really good delta in positions, which is to say, the watch will run within a very tight tolerance, no matter what its orientation in space. Up, down, sideways, you get the idea.
Generally, clocks don't move, (Carriage clocks were designed to be carried) but if dirt starts to limit the endshake, and the clock is dirty, the engagement of the wheel teeth with their adjoining pinions is kept to a narrow space, and deep ruts will be carved into the steel of the pinions. The teeth may also suffer significant wear.
When the clock is all cleaned up and endshake is restored, the wheels are freer, but will encounter the ridges of the ruts and this will interfere with the running of the clock. This is why a dirty clock will sometimes be seen to run fairly well, and if the clock is overhauled it may suddenly seem to run less well. Usually the pinions are so worn that they now cause trouble.
So what does the clockmaker do about this?
Basically, the leaves of the pinions must now be careful stoned or ground to eliminate the ridges of the ruts chewed into them over many years. This involves removing a small amount of metal, and the pinion leaf must then be polished. Preservation of the shape of the leaves is also important.
Each pinion will have 7 or more leaves, and there will be 4-6 wheels in each train, each with its own pinion. A Chiming clock has three trains, a Striking clock has two. A single train will be found in a Time-only clock like a regulator. Each leaf will be carefully repaired and then polished. Hopefully at the end of this procedure, the pinion is still within tolerance. If not, it must be replaced, and that can be.......expensive. This means that individual pinions must be cut, and this is a specialized service that is very hard to come by. On cheaper clocks with lantern pinions, (instead of leaves, the pinion has hardened wires like staves) the wires can be replaced. One by one, and this is quite tedious as we are working with blue rod and cutting and stoning the ends.....*
Lots of work, and takes lots of time to do it.
So what do we want to do?
Why, 'Prevent the clock from getting so messed up!' I hear you say.
Why yes, that is what we want.
There will be a quiz next week.........
*If a lantern pinion fails, that means one of the staves has worn completely through and the clock will suddenly release all its energy, shearing off teeth, bending very thick steel arbors, and basically tearing itself apart. In cases like this, the clockmaker may recommend defenestration or dropping the clock into the canal.