I am often asked what goes into servicing a clock. When a clock needs servicing it may start to do a number of things. The most common is it will start to loose time, not run the full week or stop erratically at various points.
The main thing that causes this is wear on the pivots and bushes. The pivots are the ends of the arbours that the wheels sit on, they sit in bushes in the brass plates of the clock. The steel pivots running on the brass bushes has a slight natural lubricating effect. Overtime the steel pivots start to wear and become rough and sticky.
It is for this reason that just going over and oiling a clock in need of servicing and overhauling does not do any good. In the short term oiling a clock in need of overhauling may get it running, however in the long run it generally causes problems. The oil when mixed with the worn steel from the pivots can actually become a cutting agent, actually increasing and speeding up the wear. The pivots can become extremely worn, sometimes to the point where they need to be removed and new pivots drilled in. On top of this the bushes start to become elongated causing the pivots to move latterally. This stops the clock by causing the wheel and pinion to nip and jam on each other.
During a carriage clock service (or any clock service for that matter) the clock is completely stripped down to its component parts. The pivots are put into a lathe and refaced with a very fine file and then polished with a burnisher. The plates are then bushed (if needed) to compensate for any reduction in pivot size and to remove any wear to the pivot hole.
On a carriage clock the platform escapement is also stripped down and put through a specialised cleaner.
The images below show the general process of a carriage clock repair.
