Post by Fridrikr TomassonI have a weight-driven grandfather clock. Here is my problem. Even though
the tick-tock is correct, the clock will run about 15-20 minutes and then
stop. I try advancing the minute hand, but it is "jammed" or "locked" - it
simply won't move forward.
Any ideas?
The minute hand should be moved anti-clockwise back to the correct time on a
rack striking clock. This avoids having to move the hands forward and listen
to each and every strike on the hour which you must do when setting a clock
forward.
Moving the hand in reverse will easily slip past the lifting pin and not
allow the rack to drop. When the minute hand approaches a couple of minutes
before the hour, the rack will drop (onto the strike snail) and on the hour
(the gathering pallet pin activates and) the clock strikes the hour. Often,
if the strike train runs down before the going train, the hands will jam at
a couple of minutes to 1. This is because the 12 step on the snail is
deepest and the strike detent pin jams at the 1 position on the snail as it
has not been gathered up because the strike train is unwound.
Check that the strike train weight is wound up and that the gut line has not
slipped off the pully, assuming it is an antique longcase eight-day clock.
If it is a modern clock made in the last 120 years then you may have a
strike/silent lever on the dial. In which case you can set it to silent and
the strike lifting pin is disengaged.
The lifting pin on the motion work behind the dial is designed to engage and
lift the thin sprung brass finger to activate the strike. However, on
antique longcases this sprung detent lever is often badly adjusted, breaks,
then repaired with solder whose heat softens up the brass and takes away the
springyness it needs to slip behind the snail and not stop the hands. So
easily hammered lightly to impart necessary springyness after repair.
Ian