© Mathew Porton FBHI 2017. Tempus Fugit Velut Umbra Barnt Green, Worcestershire, West Midlands
Although clocks can suffer wear and damage to any part there are many common areas where work is needed:-
The picture above shows a mainspring where the eye that holds the spring has begun to tear. If left the spring could fail completely and the resulting shock through the train can cause extensive damage to many components of the clock. The picture to the right shows where this has happened. Looking closely it can be seen that the steel arbor has been bent by the force of the spring unwinding suddenly. This illustrates why it is important that mainsprings are always removed during servicing and checked for the early signs of failure. Failures of this kind cannot completely be eliminated but I always remove, clean and check mainsprings to reduce the risk of it happening.
Another reason to remove mainsprings is to check that they are still in good condition and powerful enough to run the clock. Over time springs will permanently “set” and their output will be much reduced. The picture to the left shows two springs of the same dimensions (thickness, width, length). The one on the left is the old spring taken from the clock and the one on the right is the equivalent new spring which opens up far more.
Below is a countwheel from a striking clock. It shows a section of the teeth which control the number of blows struck each time the hour or half-hour is passed. In the centre it can be seen that the long slender tooth is very slightly bent (perhaps from the clock being knocked or jolted as it was striking). This small bend was enough to cause the clock to strike incorrectly every time the tooth passed by and so caused the strike to go out of sync with the time shown on the dial.
The picture to the left shows where a pivot has worn significantly in the bearing. The wear has elongated the bearing hole so that the pivot is no longer held firmly in the position it was designed to be. Below is a side view of the pivot which is also badly worn. This degree of wear can result from a pivot running without proper, clean lubrication. A dry, dirty pivot hole will increase the speed that wear occurs. In extreme cases the wear can cause the teeth of the wheel or pinion to lose mesh with the neighbouring wheel or pinion. If this happens then the clock can run away in an uncontrolled manner and serious damage can be caused by the force of the spring or weight driving the clock. When the wear to the pivot gets too great to remove by refinishing its surface then the pivot can be cut off the end of the arbor and replaced.