Erratic timekeeping
A clock may appear to be losing and/or gaining time when in fact there is no problem with its timekeeping! This apparent problem can be caused if the minute hand slips. On many traditional English eight-day clocks, the centre arbor carries a cannon wheel, against which a tension spring presses and to which the minute hand is fitted. If the tension spring is too weak the hands will not always carry (ie they can slip) and the clock will appear to lose time. A hand may carry perfectly well until the warning or rack-release is engaged, at which point this extra work can cause a slightly weak friction set-up to slip. A very simple way to check that the hands are carrying correctly is to turn the minute hand until it is exactly in line with the pin for the hand retaining collet (the time shown being irrelevant) then let the clock run for a few days or a week, without the hands being touched. At the end of the test period the minute hand should still be exactly in line with the pin as at the start.
This is well worth doing, after restoration or repairs, and before attempting to bring to time.
Chris Jenkins MBHI, UK
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