Anniversary clocks

Anniversary clocks with their highly polished brass look wonderful when well lit and are particularly good in sunshine.

Mechanical (wind-up) anniversary clocks were made in two phases, from 1841 to 1914 and 1929 to 1986 with peak production during the 1950s.

 With modern suspension springs these clocks are quite capable of keeping time within a minute per week in spite of changes in room temperature.

Here are some hints to help you get the best out of these clocks.

Set it level on a firm surface, wobbling is particularly bad for these clocks.

Old anniversary clocks, mostly pre 1914, rarely have any means of levelling them apart from making sure that the location of the clock itself is level. Check with a spirit level or look closely at the pendulum, both from the front and the side to show that its suspension wire is perpendicular to the base of the movement (works) and parallel to the back of the movement, the pendulum itself should now be central when looking at the front of the clock.

Newer clocks are easier to check as they generally have both a pendulum locking device and one adjustable foot.  It is best to position the clock with the pendulum locked, release the lock carefully and see that the lower end of the pendulum rod remains in line with the hole in the locking device. If it does not then use the adjustable foot to bring it back in line.  The pictures below show the way of setting the clock level.

Make a quick check that the escapement looks similar to one of the pictures below, it is important that the impulse pin has freedom to move within the fork fixed to the pendulum suspension spring.

Old style of anniversary clock with solid pallets and an open ended fork.

Newer form of anniversary clock where the fork has a closed end and pin pallets are used.

Wind the anniversary clock up by about three full revolutions of the key, as timekeeping tends to be different from the usual when fully wound or nearly run down, say three full turns of the key. Lock the pendulum while winding, if this facility is available.

Turn the pendulum 3/4 of a turn in either direction and release it, this should be quite sufficient to start the clock.

If you look carefully at the escapement, shown in the pictures above, the escape wheel should be moving forward as the pendulum turns one way then the other.

If the escape wheel is not turning then the anniversary clock may require servicing which is something I can do for you.

Set to time.  Just push the minute hand around until the correct time is shown. The escapement may flutter to and fro rapidly as particular points in the pendulum’s swing; this is normal and generally indicates that the anniversary clock escapement is in good order.

Check the timekeeping over a few days.  If it is within a minute of the correct time then leave it for a week and see what has happened. In either case repeat the test and see if the results are consistent, if not then I can service it for you.

Regulate the clock, it should be possible to reduce the error to less than three minutes a week, I have clocks which run within 1/2 a minute either side of the correct rate.  Note the amount of swing on the pendulum from one stopping point to the other, on old clocks this could be less than a full turn, before making adjustments; hold the pendulum when you adjust it; release it and bring it to rest by stopping it as near as possible to the mid-point of its swing and waiting for it to stop moving. Turn it by half the amount of swing you noted and release it.  Doing this means that it will settle to normal operation more quickly.

Old anniversary clocks.  These often look like the picture below where sliding weights are moved by a screw which has squared ends. If you are lucky then the weights are marked with ‘A’ and ‘R’ for advance and retard which tells you which way to turn the screw to achieve the desired affect. If not then you need to look carefully at the thread on the screw to work out the direction of turn.

Detail of screw thread showing that turning the screw clockwise, in this case, will move the weight inwards, causing the clock to run faster.

IA suitable starting point for regulation is assuming that a 1/4 of a turn changes the rate by about 1 minute per day.

Newer anniversary clocks usually have the arrangement like this. A suitable starting point for regulation is assuming that 1/4 turn changes the rate by 5 minutes per day.

Note: Even though these clocks may run a full year they keep time better if they are wound more regularly. As a starting point wind the clock fully and let it run for about four months, then wind it up by one revolution of the key. Keep on winding a similar amount at three month intervals. If the clock eventually ends up fully wound again then you need a larger interval between winding, the opposite if the clock ends up completely run down.

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